@article{Helmuth:2021:ALifeJournal, author = {Thomas Helmuth and Lee Spector}, title = {Problem-solving benefits of down-sampled lexicase selection}, journal = {Artificial Life}, year = {2021}, note = {In press}, doi-url = {}, url = {}, pdf = {https://arxiv.org/pdf/2106.06085.pdf} }
@article{Helmuth:2020:GPEM, author = {Thomas Helmuth and Edward Pantridge and Lee Spector}, title = {On the importance of specialists for lexicase selection}, journal = {Genetic Programming and Evolvable Machines}, publisher = {Springer}, year = {2020}, volume = {21}, number = {3}, pages = {349--373}, month = sep, note = {Special Issue: Highlights of Genetic Programming 2019 Events}, keywords = {genetic algorithms, genetic programming, Lexicase selection, Specialists, Parent selection, Program synthesis}, issn = {1389-2576}, doi = {doi:10.1007/s10710-020-09377-2}, size = {25 pages}, abstract = {Lexicase parent selection filters the population by considering one random training case at a time, eliminating any individual with an error for the current case that is worse than the best error of any individual in the selection pool, until a single individual remains. This process often stops before considering all training cases, meaning that it will ignore the error values on any cases that were not yet considered. Lexicase selection can therefore select specialist individuals that have high errors on some training cases, if they have low errors on others and those errors come near the start of the random list of cases used for the parent selection event in question. We hypothesize here that selecting such specialists, which may have high total error, plays an important role in lexicase selection observed performance advantages over error-aggregating parent selection methods such as tournament selection, which select specialists less frequently. We conduct experiments examining}, doi-url = {http://dx.doi.org/10.1007/s10710-020-09377-2}, url = {https://link.springer.com/article/10.1007%2Fs10710-020-09377-2}, pdf = {http://cs.hamilton.edu/~thelmuth/Pubs/2020-GPEM-lexicase-specialists.pdf} }
@article{LaCava:2019:ecj, author = {William {La Cava} and Thomas Helmuth and Lee Spector and Jason H. Moore}, title = {A probabilistic and multi-objective analysis of lexicase selection and epsilon-lexicase selection}, journal = {Evolutionary Computation}, year = {2019}, url = {https://www.mitpressjournals.org/doi/pdf/10.1162/evco_a_00224}, pdf = {https://arxiv.org/pdf/1709.05394.pdf}, keywords = {genetic algorithms, genetic programming}, issn = {1063-6560}, doi = {doi:10.1162/evco_a_00224}, size = {28 pages}, abstract = {Lexicase selection is a parent selection method that considers training cases individually, rather than in aggregate, when performing parent selection. Whereas previous work has demonstrated the ability of lexicase selection to solve difficult problems in program synthesis and symbolic regression, the central goal of this paper is to develop the theoretical underpinnings that explain its performance. To this end, we derive an analytical formula that gives the expected probabilities of selection under lexicase selection, given a population and its behaviour. In addition, we expand upon the relation of lexicase selection to many-objective optimization methods to describe the behavior of lexicase selection, which is to select individuals on the boundaries of Pareto fronts in high-dimensional space. We show analytically why lexicase selection performs more poorly for certain sizes of population and training cases, and show why it has been shown to perform more poorly in continuous error spaces. To address this last concern, we propose new variants of epsilon-lexicase selection, a method that modifies the pass condition in lexicase selection to allow near-elite individuals to pass cases, thereby improving selection performance with continuous errors. We show that epsilon-lexicase outperforms several diversity-maintenance strategies on a number of real-world and synthetic regression problems.}, doi-url = {http://dx.doi.org/10.1162/evco_a_00224} }
@article{Helmuth:2015:ieeeTEC, author = {Thomas Helmuth and Lee Spector and James Matheson}, title = {Solving Uncompromising Problems with Lexicase Selection}, journal = {IEEE Transactions on Evolutionary Computation}, year = {2015}, volume = {19}, number = {5}, pages = {630--643}, month = oct, keywords = {genetic algorithms, genetic programming, parent selection, lexicase selection, tournament selection, PushGP}, issn = {1089-778X}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=6920034}, doi = {doi:10.1109/TEVC.2014.2362729}, pdf = {http://cs.hamilton.edu/~thelmuth/Pubs/lexicase-IEEETEC-2014.pdf}, size = {14 pages}, abstract = {We describe a broad class of problems, called uncompromising problems, characterised by the requirement that solutions must perform optimally on each of many test cases. Many of the problems that have long motivated genetic programming research, including the automation of many traditional programming tasks, are uncompromising. We describe and analyse the recently proposed lexicase parent selection algorition and show that it can facilitate the solution of uncompromising problems by genetic programming. Unlike most traditional parent selection techniques, lexicase selection does not base selection on a fitness value that is aggregated over all test cases; rather, it considers test cases one at a time in random order. We present results comparing lexicase selection to more traditional parent selection methods, including standard tournament selection and implicit fitness sharing, on four uncompromising problems: finding terms in finite algebras, designing digital multipliers, counting words in files, and performing symbolic regression of the factorial function. We provide evidence that lexicase selection maintains higher levels of population diversity than other selection methods, which may partially explain its utility as a parent selection algorithm in the context of uncompromising problems.}, notes = {also known as \cite{6920034}}, doi-url = {http://dx.doi.org/10.1109/TEVC.2014.2362729} }
@inproceedings{Helmuth:2021:GECCO:PSB2, author = {Thomas Helmuth and Peter Kelly}, title = {{PSB2}: The Second Program Synthesis Benchmark Suite}, booktitle = {2021 Genetic and Evolutionary Computation Conference}, series = {GECCO '21}, year = {2021}, isbn13 = {978-1-4503-8350-9}, address = {Lille, France}, size = {10 pages}, doi = {10.1145/3449639.3459285}, publisher = {ACM}, publisher_address = {New York, NY, USA}, month = {10-14} # jul, doi-url = {https://doi.org/10.1145/3449639.3459285}, url = {https://dl.acm.org/doi/10.1145/3449639.3459285}, pdf = {https://arxiv.org/pdf/2106.06086.pdf}, associated = {https://cs.hamilton.edu/~thelmuth/PSB2/PSB2.html}, note = {\textbf{Nominated, Best Paper Award, Genetic Programming Track}} }
@inproceedings{Helmuth:2020:ALife:downsampledlexicase, author = {Helmuth, Thomas and Spector, Lee}, title = {Explaining and Exploiting the Advantages of Down-sampled Lexicase Selection}, booktitle = {Artificial Life Conference Proceedings}, publisher = {MIT Press}, pages = {341-349}, month = {13-18 } # jul, year = {2020}, doi = {10.1162/isal_a_00334}, url = {https://direct.mit.edu/isal/proceedings/isal2020/32/341/98485}, pdf = {https://direct.mit.edu/isal/proceedings-pdf/isal2020/32/341/1908528/isal_a_00334.pdf}, video = {https://youtu.be/IR14htbTatg}, abstract = { In genetic programming, parent selection is ordinarily based on aggregate measures of performance across an entire training set. Lexicase selection, by contrast, selects on the basis of performance on random sequences of test cases; this has been shown to enhance problem-solving power in many circumstances. Lexicase selection can also be seen as better reflecting biological evolution, by modeling sequences of challenges that organisms face over their lifetimes. Recent work has demonstrated that the advantages of lexicase selection can be amplified by down-sampling, meaning that only a random subsample of the training cases is used each generation, which can also be seen as modeling environmental change over time. Here we provide the most extensive benchmarking of down-sampled lexicase selection to date, showing that its benefits hold up to increased scrutiny. The reasons that down-sampling helps, however, are not yet fully understood. Hypotheses include that down-sampling allows for more generations to be processed with the same budget of program evaluations; that the variation of training data across generations acts as a changing environment, encouraging adaptation; or that it reduces overfitting, leading to more general solutions. We systematically evaluate these hypotheses, finding evidence against all three, and instead draw the conclusion that down-sampled lexicase selection's main benefit stems from the fact that it allows GP to examine more individuals within the same computational budget, even though each individual is examined less completely. } }
@inproceedings{Helmuth:2020:ALife:source, author = {Helmuth, Thomas and Pantridge, Edward and Woolson, Grace and Spector, Lee}, title = {Genetic Source Sensitivity and Transfer Learning in Genetic Programming}, booktitle = {Artificial Life Conference Proceedings}, publisher = {MIT Press}, pages = {303-311}, month = {13-18 } # jul, year = {2020}, doi = {10.1162/isal_a_00326}, url = {https://direct.mit.edu/isal/proceedings/isal2020/32/303/98422}, pdf = {https://direct.mit.edu/isal/proceedings-pdf/isal2020/32/303/1908486/isal_a_00326.pdf}, video = {https://youtu.be/w1ogl2oNVgc}, abstract = { Genetic programming uses biologically-inspired processes of variation and selection to synthesize computer programs that solve problems. Here we investigate the sensitivity of genetic programming to changes in the probability that particular instructions and constants will be chosen for inclusion in randomly generated programs or for introduction by mutation. We find, contrary to conventional wisdom within the field, that genetic programming can be highly sensitive to changes in this source of new genetic material. Additionally, we find that genetic sources can be tuned to significantly improve adaptation across sets of related problems. We study the evolution of solutions to software synthesis problems using untuned genetic sources and sources that have been tuned on the basis of problem statements, human intuition, or prevalence in prior solution programs. We find significant differences in performance across these approaches, and use these lessons to develop a method for tuning genetic sources on the basis of evolved solutions to related problems. This “transfer learning” approach tunes genetic sources nearly as well as humans do, but by means of a fully automated process that can be applied to previously unsolved problems. } }
@inproceedings{Helmuth:2019:GECCO, author = {Thomas Helmuth and Edward Pantridge and Lee Spector}, title = {Lexicase selection of specialists}, booktitle = {GECCO '19: Proceedings of the Genetic and Evolutionary Computation Conference}, year = {2019}, noeditor = {Manuel Lopez-Ibanez and Thomas Stuetzle and Anne Auger and Petr Posik and Leslie {Peprez Caceres} and Andrew M. Sutton and Nadarajen Veerapen and Christine Solnon and Andries Engelbrecht and Stephane Doncieux and Sebastian Risi and Penousal Machado and Vanessa Volz and Christian Blum and Francisco Chicano and Bing Xue and Jean-Baptiste Mouret and Arnaud Liefooghe and Jonathan Fieldsend and Jose Antonio Lozano and Dirk Arnold and Gabriela Ochoa and Tian-Li Yu and Holger Hoos and Yaochu Jin and Ting Hu and Miguel Nicolau and Robin Purshouse and Thomas Baeck and Justyna Petke and Giuliano Antoniol and Johannes Lengler and Per Kristian Lehre}, isbn13 = {978-1-4503-6111-8}, pages = {1030--1038}, address = {Prague, Czech Republic}, doi = {doi:10.1145/3321707.3321875}, publisher = {ACM}, publisher_address = {New York, NY, USA}, month = {13-17 } # jul, organisation = {SIGEVO}, keywords = {genetic algorithms, genetic programming}, notes = {Also known as \cite{3321875} GECCO-2019 A Recombination of the 28th International Conference on Genetic Algorithms (ICGA) and the 24th Annual Genetic Programming Conference (GP)}, doi-url = {http://dx.doi.org/10.1145/3321707.3321875}, url = {https://dl.acm.org/citation.cfm?doid=3321707.3321875}, pdf = {https://arxiv.org/pdf/1905.09372.pdf}, note = {\textbf{Winner of Best Paper Award, Genetic Programming Track} (38\% acceptance rate out of 39 submissions in track, 3 best paper nominations)} }
@inproceedings{Jundt:2019:GECCO, author = {Lia Jundt and Thomas Helmuth}, title = {Comparing and combining lexicase selection and novelty search}, booktitle = {GECCO '19: Proceedings of the Genetic and Evolutionary Computation Conference}, year = {2019}, noeditor = {Manuel Lopez-Ibanez and Thomas Stuetzle and Anne Auger and Petr Posik and Leslie {Peprez Caceres} and Andrew M. Sutton and Nadarajen Veerapen and Christine Solnon and Andries Engelbrecht and Stephane Doncieux and Sebastian Risi and Penousal Machado and Vanessa Volz and Christian Blum and Francisco Chicano and Bing Xue and Jean-Baptiste Mouret and Arnaud Liefooghe and Jonathan Fieldsend and Jose Antonio Lozano and Dirk Arnold and Gabriela Ochoa and Tian-Li Yu and Holger Hoos and Yaochu Jin and Ting Hu and Miguel Nicolau and Robin Purshouse and Thomas Baeck and Justyna Petke and Giuliano Antoniol and Johannes Lengler and Per Kristian Lehre}, isbn13 = {978-1-4503-6111-8}, pages = {1047--1055}, address = {Prague, Czech Republic}, doi = {doi:10.1145/3321707.3321787}, publisher = {ACM}, publisher_address = {New York, NY, USA}, month = {13-17 } # jul, organisation = {SIGEVO}, keywords = {genetic algorithms, genetic programming}, notes = {Also known as \cite{3321787} GECCO-2019 A Recombination of the 28th International Conference on Genetic Algorithms (ICGA) and the 24th Annual Genetic Programming Conference (GP)}, doi-url = {http://dx.doi.org/10.1145/3321707.3321787}, url = {https://dl.acm.org/citation.cfm?doid=3321707.3321787}, pdf = {https://arxiv.org/pdf/1905.09374.pdf} }
@inproceedings{Helmuth:2018:GECCO, author = {Thomas Helmuth and Nicholas Freitag McPhee and Lee Spector}, title = {Program synthesis using uniform mutation by addition and deletion}, booktitle = {GECCO '18: Proceedings of the Genetic and Evolutionary Computation Conference}, year = {2018}, noeditor = {Hernan Aguirre and Keiki Takadama and Hisashi Handa and Arnaud Liefooghe and Tomohiro Yoshikawa and Andrew M. Sutton and Satoshi Ono and Francisco Chicano and Shinichi Shirakawa and Zdenek Vasicek and Roderich Gross and Andries Engelbrecht and Emma Hart and Sebastian Risi and Ekart Aniko and Julian Togelius and S{\'e}bastien Verel and Christian Blum and Will Browne and Yusuke Nojima and Tea Tusar and Qingfu Zhang and Nikolaus Hansen and Jose Antonio Lozano and Dirk Thierens and Tian-Li Yu and J{\"u}rgen Branke and Yaochu Jin and Sara Silva and Hitoshi Iba and Anna I Esparcia-Alcazar and Thomas Bartz-Beielstein and Federica Sarro and Giuliano Antoniol and Anne Auger and Per Kristian Lehre}, isbn13 = {978-1-4503-5618-3}, pages = {1127--1134}, address = {Kyoto, Japan}, url = {http://doi.acm.org/10.1145/3205455.3205603}, doi = {doi:10.1145/3205455.3205603}, pdf = {http://cs.hamilton.edu/~thelmuth/Pubs/2018-GECCO-UMAD.pdf}, publisher = {ACM}, publisher_address = {New York, NY, USA}, month = {15-19 } # jul, organisation = {SIGEVO}, keywords = {genetic algorithms, genetic programming}, notes = {Also known as \cite{3205603} GECCO-2018 A Recombination of the 27th International Conference on Genetic Algorithms (ICGA-2018) and the 23rd Annual Genetic Programming Conference (GP-2018)}, doi-url = {http://dx.doi.org/10.1145/3205455.3205603}, note = {\textbf{Winner of Best Paper Award, Genetic Programming Track} (37\% acceptance rate out of 30 submissions in track, 3 best paper nominations)} }
@inproceedings{Helmuth:2017:GECCO, author = {Thomas Helmuth and Nicholas Freitag McPhee and Edward Pantridge and Lee Spector}, title = {Improving Generalization of Evolved Programs Through Automatic Simplification}, booktitle = {Proceedings of the Genetic and Evolutionary Computation Conference}, series = {GECCO '17}, year = {2017}, isbn13 = {978-1-4503-4920-8}, address = {Berlin, Germany}, pages = {937--944}, size = {8 pages}, url = {http://doi.acm.org/10.1145/3071178.3071330}, doi = {doi:10.1145/3071178.3071330}, pdf = {http://cs.hamilton.edu/~thelmuth/Pubs/2017-GECCO-simplification-for-generalization.pdf}, acmid = {3071330}, publisher = {ACM}, publisher_address = {New York, NY, USA}, keywords = {genetic programming, automatic simplification, generalization, overfitting, Push}, month = {15-19 } # jul, notes = {Also known as \cite{Helmuth:2017:IGE:3071178.3071330} GECCO-2017 A Recombination of the 26th International Conference on Genetic Algorithms (ICGA-2017) and the 22nd Annual Genetic Programming Conference (GP-2017)}, doi-url = {http://dx.doi.org/10.1145/3071178.3071330}, note = {\textbf{Nominated, Best Paper Award, Genetic Programming Track} (36\% acceptance rate out of 47 submissions in track, 3 best paper nominations)} }
@inproceedings{Helmuth:2016:GECCO, author = {Thomas Helmuth and Nicholas Freitag McPhee and Lee Spector}, title = {The Impact of Hyperselection on Lexicase Selection}, booktitle = {GECCO '16: Proceedings of the 2016 conference on Genetic and Evolutionary Computation Conference}, year = {2016}, editor = {Tobias Friedrich}, pages = {717--724}, keywords = {genetic algorithms, genetic programming}, month = {20-24 } # jul, organisation = {SIGEVO}, address = {Denver, USA}, publisher = {ACM}, publisher_address = {New York, NY, USA}, isbn13 = {978-1-4503-4206-3}, doi = {doi:10.1145/2908812.2908851}, url = {http://doi.acm.org/10.1145/2908812.2908851}, pdf = {http://cs.hamilton.edu/~thelmuth/Pubs/2016-GECCO-hyperselection.pdf}, abstract = {Lexicase selection is a parent selection method that has been shown to improve the problem solving power of genetic programming over a range of problems. Previous work has shown that it can also produce hyperselection events, in which a single individual is selected many more times than other individuals. Here we investigate the role that hyperselection plays in the problem-solving performance of lexicase selection. We run genetic programming on a set of program synthesis benchmark problems using lexicase and tournament selection, confirming that hyperselection occurs significantly more often and more drastically with lexicase selection, which also performs significantly better. We then show results from an experiment indicating that hyperselection is not integral to the problem-solving performance or diversity maintenance observed when using lexicase selection. We conclude that the power of lexicase selection stems from the collection of individuals that it selects, not from the unusual frequencies with which it sometimes selects them.}, notes = {Washington and Lee University, University of Minnesota Morris, Hampshire College GECCO-2016 A Recombination of the 25th International Conference on Genetic Algorithms (ICGA-2016) and the 21st Annual Genetic Programming Conference (GP-2016)}, doi-url = {http://dx.doi.org/10.1145/2908812.2908851}, note = {\textbf{Nominated, Best Paper Award, Genetic Programming Track} (39\% acceptance rate out of 31 submissions in track, 3 best paper nominations)} }
@inproceedings{Helmuth:2015:GECCO, author = {Thomas Helmuth and Lee Spector}, title = {General Program Synthesis Benchmark Suite}, booktitle = {GECCO '15: Proceedings of the 2015 conference on Genetic and Evolutionary Computation Conference}, year = {2015}, noeditor = {Sara Silva and Anna I Esparcia-Alcazar and Manuel Lopez-Ibanez and Sanaz Mostaghim and Jon Timmis and Christine Zarges and Luis Correia and Terence Soule and Mario Giacobini and Ryan Urbanowicz and Youhei Akimoto and Tobias Glasmachers and Francisco {Fernandez de Vega} and Amy Hoover and Pedro Larranaga and Marta Soto and Carlos Cotta and Francisco B. Pereira and Julia Handl and Jan Koutnik and Antonio Gaspar-Cunha and Heike Trautmann and Jean-Baptiste Mouret and Sebastian Risi and Ernesto Costa and Oliver Schuetze and Krzysztof Krawiec and Alberto Moraglio and Julian F. Miller and Pawel Widera and Stefano Cagnoni and JJ Merelo and Emma Hart and Leonardo Trujillo and Marouane Kessentini and Gabriela Ochoa and Francisco Chicano and Carola Doerr}, isbn13 = {978-1-4503-3472-3}, pages = {1039--1046}, keywords = {genetic algorithms, genetic programming}, month = {11-15 } # jul, organisation = {SIGEVO}, address = {Madrid, Spain}, url = {http://doi.acm.org/10.1145/2739480.2754769}, doi = {doi:10.1145/2739480.2754769}, pdf = {http://cs.hamilton.edu/~thelmuth/Pubs/2015-GECCO-benchmark-suite.pdf}, associated = {http://thelmuth.github.io/GECCO_2015_Benchmarks_Materials/}, publisher = {ACM}, publisher_address = {New York, NY, USA}, abstract = {Recent interest in the development and use of non-trivial benchmark problems for genetic programming research has highlighted the scarcity of general program synthesis (also called traditional programming) benchmark problems. We present a suite of 29 general program synthesis benchmark problems systematically selected from sources of introductory computer science programming problems. This suite is suitable for experiments with any program synthesis system driven by input/output examples. We present results from illustrative experiments using our reference implementation of the problems in the PushGP genetic programming system. The results show that the problems in the suite vary in difficulty and can be useful for assessing the capabilities of a program synthesis system.}, notes = {Also known as \cite{2754769} GECCO-2015 A joint meeting of the twenty fourth international conference on genetic algorithms (ICGA-2015) and the twentith annual genetic programming conference (GP-2015)}, doi-url = {http://dx.doi.org/10.1145/2739480.2754769} }
@inproceedings{LaCava:2015:GECCO, author = {William {La Cava} and Thomas Helmuth and Lee Spector and Kourosh Danai}, title = {Genetic Programming with Epigenetic Local Search}, booktitle = {GECCO '15: Proceedings of the 2015 conference on Genetic and Evolutionary Computation Conference}, year = {2015}, noeditor = {Sara Silva and Anna I Esparcia-Alcazar and Manuel Lopez-Ibanez and Sanaz Mostaghim and Jon Timmis and Christine Zarges and Luis Correia and Terence Soule and Mario Giacobini and Ryan Urbanowicz and Youhei Akimoto and Tobias Glasmachers and Francisco {Fernandez de Vega} and Amy Hoover and Pedro Larranaga and Marta Soto and Carlos Cotta and Francisco B. Pereira and Julia Handl and Jan Koutnik and Antonio Gaspar-Cunha and Heike Trautmann and Jean-Baptiste Mouret and Sebastian Risi and Ernesto Costa and Oliver Schuetze and Krzysztof Krawiec and Alberto Moraglio and Julian F. Miller and Pawel Widera and Stefano Cagnoni and JJ Merelo and Emma Hart and Leonardo Trujillo and Marouane Kessentini and Gabriela Ochoa and Francisco Chicano and Carola Doerr}, isbn13 = {978-1-4503-3472-3}, pages = {1055--1062}, keywords = {genetic algorithms, genetic programming}, month = {11-15 } # jul, organisation = {SIGEVO}, address = {Madrid, Spain}, url = {http://doi.acm.org/10.1145/2739480.2754763}, doi = {doi:10.1145/2739480.2754763}, pdf = {http://hampshire.edu/lspector/pubs/Epigenetics_2015_GECCO_final.pdf}, publisher = {ACM}, publisher_address = {New York, NY, USA}, abstract = {We focus on improving genetic programming through local search of the space of program structures using an inheritable epigenetic layer that specifies active and inactive genes. We explore several genetic programming implementations that represent the different properties that epigenetics can provide, such as passive structure, phenotypic plasticity, and inheritable gene regulation. We apply these implementations to several symbolic regression and program synthesis problems. For the symbolic regression problems, the results indicate that epigenetic local search consistently improves genetic programming by producing smaller solution programs with better fitness. Furthermore, we find that incorporating epigenetic modification as a mutation step in program synthesis problems can improve the ability of genetic programming to find exact solutions. By analyzing population homology we show that the epigenetic implementations maintain diversity in silenced portions of programs which may provide protection from premature convergence.}, notes = {Also known as \cite{2754763} GECCO-2015 A joint meeting of the twenty fourth international conference on genetic algorithms (ICGA-2015) and the twentith annual genetic programming conference (GP-2015)}, doi-url = {http://dx.doi.org/10.1145/2739480.2754763}, note = {\textbf{Nominated, Best Paper Award, Genetic Programming Track} (44\% acceptance rate out of 45 submissions in track, 3 best paper nominations)} }
@inproceedings{Helmuth:2014:GECCO, author = {Thomas Helmuth and Lee Spector}, title = {Word count as a traditional programming benchmark problem for genetic programming}, booktitle = {GECCO '14: Proceedings of the 2014 conference on Genetic and evolutionary computation}, year = {2014}, noeditor = {Christian Igel and Dirk V. Arnold and Christian Gagne and Elena Popovici and Anne Auger and Jaume Bacardit and Dimo Brockhoff and Stefano Cagnoni and Kalyanmoy Deb and Benjamin Doerr and James Foster and Tobias Glasmachers and Emma Hart and Malcolm I. Heywood and Hitoshi Iba and Christian Jacob and Thomas Jansen and Yaochu Jin and Marouane Kessentini and Joshua D. Knowles and William B. Langdon and Pedro Larranaga and Sean Luke and Gabriel Luque and John A. W. McCall and Marco A. {Montes de Oca} and Alison Motsinger-Reif and Yew Soon Ong and Michael Palmer and Konstantinos E. Parsopoulos and Guenther Raidl and Sebastian Risi and Guenther Ruhe and Tom Schaul and Thomas Schmickl and Bernhard Sendhoff and Kenneth O. Stanley and Thomas Stuetzle and Dirk Thierens and Julian Togelius and Carsten Witt and Christine Zarges}, isbn13 = {978-1-4503-2662-9}, pages = {919--926}, keywords = {genetic algorithms, genetic programming}, month = {12-16 } # jul, organisation = {SIGEVO}, address = {Vancouver, BC, Canada}, url = {http://doi.acm.org/10.1145/2576768.2598230}, doi = {doi:10.1145/2576768.2598230}, pdf = {https://github.com/thelmuth/GECCO_2014_WC_Materials/raw/master/wc.pdf}, associated = {http://thelmuth.github.io/GECCO_2014_WC_Materials/}, publisher = {ACM}, publisher_address = {New York, NY, USA}, abstract = {The Unix utility program wc, which stands for word count, takes any number of files and prints the number of newlines, words, and characters in each of the files. We show that genetic programming can find programs that replicate the core functionality of the wc utility, and propose this problem as a traditional programming benchmark for genetic programming systems. This wc problem features key elements of programming tasks that often confront human programmers, including requirements for multiple data types, a large instruction set, control flow, and multiple outputs. Furthermore, it mimics the behavior of a real-world utility program, showing that genetic programming can automatically synthesize programs with general utility. We suggest statistical procedures that should be used to compare performances of different systems on traditional programming problems such as the wc problem, and present the results of a short experiment using the problem. Finally, we give a short analysis of evolved solution programs, showing how they make use of traditional programming concepts.}, notes = {Also known as \cite{2598230} GECCO-2014 A joint meeting of the twenty third international conference on genetic algorithms (ICGA-2014) and the nineteenth annual genetic programming conference (GP-2014)}, doi-url = {http://dx.doi.org/10.1145/2576768.2598230} }
@inproceedings{Spector:2012:GECCO, author = {Lee Spector and Kyle Harrington and Thomas Helmuth}, title = {Tag-based modularity in tree-based genetic programming}, booktitle = {GECCO '12: Proceedings of the fourteenth international conference on Genetic and evolutionary computation conference}, year = {2012}, noeditor = {Terry Soule and Anne Auger and Jason Moore and David Pelta and Christine Solnon and Mike Preuss and Alan Dorin and Yew-Soon Ong and Christian Blum and Dario Landa Silva and Frank Neumann and Tina Yu and Aniko Ekart and Will Browne and Tim Kovacs and Man-Leung Wong and Clara Pizzuti and Jon Rowe and Tobias Friedrich and Giovanni Squillero and Nicolas Bredeche and Stephen Smith and Alison Motsinger-Reif and Jose Lozano and Martin Pelikan and Silja Meyer-Nienberg and Christian Igel and Greg Hornby and Rene Doursat and Steve Gustafson and Gustavo Olague and Shin Yoo and John Clark and Gabriela Ochoa and Gisele Pappa and Fernando Lobo and Daniel Tauritz and Jurgen Branke and Kalyanmoy Deb}, isbn13 = {978-1-4503-1177-9}, pages = {815--822}, keywords = {genetic algorithms, genetic programming}, month = {7-11 } # jul, organisation = {SIGEVO}, address = {Philadelphia, Pennsylvania, USA}, url = {http://dl.acm.org/citation.cfm?doid=2330163.2330276}, doi = {doi:10.1145/2330163.2330276}, pdf = {http://hampshire.edu/lspector/pubs/p815.pdf}, publisher = {ACM}, publisher_address = {New York, NY, USA}, abstract = {Several techniques have been developed for allowing genetic programming systems to produce programs that make use of subroutines, macros, and other modular program structures. A recently proposed technique, based on the tagging and tag-based retrieval of blocks of code, has been shown to have novel and desirable features, but this was demonstrated only within the context of the PushGP genetic programming system. Following a suggestion in the GECCO-2011 publication on this technique we show here how tag-based modules can be incorporated into a more standard tree-based genetic programming system. We describe the technique in detail along with some possible extensions, outline arguments for its simplicity and potential power, and present results obtained using the technique on problems for which other modularization techniques have been shown to be useful. The results are mixed; substantial benefits are seen on the lawnmower problem but not on the Boolean even-4-parity problem. We discuss the observed results and directions for future research.}, notes = {Also known as \cite{2330276} GECCO-2012 A joint meeting of the twenty first international conference on genetic algorithms (ICGA-2012) and the seventeenth annual genetic programming conference (GP-2012)}, doi-url = {http://dx.doi.org/10.1145/2330163.2330276} }
@inproceedings{Spector:2011:GECCO, author = {Lee Spector and Brian Martin and Kyle Harrington and Thomas Helmuth}, title = {Tag-based modules in genetic programming}, booktitle = {GECCO '11: Proceedings of the 13th annual conference on Genetic and evolutionary computation}, year = {2011}, isbn13 = {978-1-4503-0557-0}, pages = {1419--1426}, keywords = {genetic algorithms, genetic programming, pushGP, lawnmower}, month = {12-16 } # jul, organisation = {SIGEVO}, address = {Dublin, Ireland}, url = {http://dl.acm.org/citation.cfm?doid=2001576.2001767}, doi = {doi:10.1145/2001576.2001767}, pdf = {http://hampshire.edu/lspector/pubs/spector-tags-gecco-2011-with-citation.pdf}, associated = {http://hampshire.edu/lspector/tags-gecco-2011/}, publisher = {ACM}, publisher_address = {New York, NY, USA}, abstract = {In this paper we present a new technique for evolving modular programs with genetic programming. The technique is based on the use of tags that evolving programs may use to label and later to refer to code fragments. Tags may refer inexactly, permitting the labelling and use of code fragments to co-evolve in an incremental way. The technique can be implemented as a minor modification to an existing, general purpose genetic programming system, and it does not require pre-specification of the module architecture of evolved programs. We demonstrate that tag-based modules readily evolve and that this allows problem solving effort to scale well with problem size. We also show that the tag-based module technique is effective even in complex, non-uniform problem environments for which previous techniques perform poorly. We demonstrate the technique in the context of the stack-based genetic programming system PushGP, but we also briefly discuss ways in which it may be used with other kinds of genetic programming systems.}, notes = {Section 7: tags in other forms of GP Tag data to be tried. Also known as \cite{2001767} GECCO-2011 A joint meeting of the twentieth international conference on genetic algorithms (ICGA-2011) and the sixteenth annual genetic programming conference (GP-2011)}, doi-url = {http://dx.doi.org/10.1145/2001576.2001767} }
@inproceedings{Ahmad:2018:GECCO, author = {Hammad Ahmad and Thomas Helmuth}, title = {A comparison of semantic-based initialization methods for genetic programming}, booktitle = {GECCO '18: Proceedings of the Genetic and Evolutionary Computation Conference Companion}, year = {2018}, noeditor = {Carlos Cotta and Tapabrata Ray and Hisao Ishibuchi and Shigeru Obayashi and Bogdan Filipic and Thomas Bartz-Beielstein and Grant Dick and Masaharu Munetomo and Silvino {Fernandez Alzueta} and Thomas Stuetzle and Pablo Valledor Pellicer and Manuel Lopez-Ibanez and Daniel R. Tauritz and Pietro S. Oliveto and Thomas Weise and Borys Wrobel and Ales Zamuda and Anne Auger and Julien Bect and Dimo Brockhoff and Nikolaus Hansen and Rodolphe {Le Riche} and Victor Picheny and Bilel Derbel and Ke Li and Hui Li and Xiaodong Li and Saul Zapotecas and Qingfu Zhang and Stephane Doncieux and Richard Duro and Joshua Auerbach and Harold {de Vladar} and Antonio J. Fernandez-Leiva and JJ Merelo and Pedro A. Castillo-Valdivieso and David Camacho-Fernandez and Francisco {Chavez de la O} and Ozgur Akman and Khulood Alyahya and Juergen Branke and Kevin Doherty and Jonathan Fieldsend and Giuseppe Carlo Marano and Nikos D. Lagaros and Koichi Nakayama and Chika Oshima and Stefan Wagner and Michael Affenzeller and Boris Naujoks and Vanessa Volz and Tea Tusar and Pascal Kerschke and Riyad Alshammari and Tokunbo Makanju and Brad Alexander and Saemundur O. Haraldsson and Markus Wagner and John R. Woodward and Shin Yoo and John McCall and Nayat Sanchez-Pi and Luis Marti and Danilo Vasconcellos and Masaya Nakata and Anthony Stein and Nadarajen Veerapen and Arnaud Liefooghe and Sebastien Verel and Gabriela Ochoa and Stephen L. Smith and Stefano Cagnoni and Robert M. Patton and William {La Cava} and Randal Olson and Patryk Orzechowski and Ryan Urbanowicz and Ivanoe {De Falco} and Antonio {Della Cioppa} and Ernesto Tarantino and Umberto Scafuri and P. G. M. Baltus and Giovanni Iacca and Ahmed Hallawa and Anil Yaman and Alma Rahat and Handing Wang and Yaochu Jin and David Walker and Richard Everson and Akira Oyama and Koji Shimoyama and Hemant Kumar and Kazuhisa Chiba and Pramudita Satria Palar}, isbn13 = {978-1-4503-5764-7}, pages = {1878--1881}, address = {Kyoto, Japan}, doi = {doi:10.1145/3205651.3208218}, url = {http://doi.acm.org/10.1145/3205651.3208218}, pdf = {http://cs.hamilton.edu/~thelmuth/Pubs/2018-GECCO-workshop-semantic-initialization.pdf}, publisher = {ACM}, publisher_address = {New York, NY, USA}, month = {15-19 } # jul, organisation = {SIGEVO}, keywords = {genetic algorithms, genetic programming}, abstract = {During the initialization step, a genetic programming (GP) system traditionally creates a population of completely random programs to populate the initial population. These programs almost always perform poorly in terms of their total error---some might not even output the correct data type. In this paper, we present new methods for initialization that attempt to generate programs that are somewhat relevant to the problem being solved and/or increase the initial diversity (both error and behavioural diversity) of the population prior to the GP run. By seeding the population---and thereby eliminating worthless programs and increasing the initial diversity of the population---we hope to improve the performance of the GP system. Here, we present two novel techniques for initialization (Lexicase Seeding and Pareto Seeding) and compare them to a previous method (Enforced Diverse Populations) and traditional, non-seeded initialization. Surprisingly, we found that none of the initialization m}, notes = {Also known as \cite{3208218} GECCO-2018 A Recombination of the 27th International Conference on Genetic Algorithms (ICGA-2018) and the 23rd Annual Genetic Programming Conference (GP-2018)}, doi-url = {http://dx.doi.org/10.1145/3205651.3208218} }
@inproceedings{Pantridge:2018:GECCO, author = {Edward Pantridge and Thomas Helmuth and Nicholas Freitag McPhee and Lee Spector}, title = {Specialization and elitism in lexicase and tournament selection}, booktitle = {GECCO '18: Proceedings of the Genetic and Evolutionary Computation Conference Companion}, year = {2018}, noeditor = {Carlos Cotta and Tapabrata Ray and Hisao Ishibuchi and Shigeru Obayashi and Bogdan Filipic and Thomas Bartz-Beielstein and Grant Dick and Masaharu Munetomo and Silvino {Fernandez Alzueta} and Thomas Stuetzle and Pablo Valledor Pellicer and Manuel Lopez-Ibanez and Daniel R. Tauritz and Pietro S. Oliveto and Thomas Weise and Borys Wrobel and Ales Zamuda and Anne Auger and Julien Bect and Dimo Brockhoff and Nikolaus Hansen and Rodolphe {Le Riche} and Victor Picheny and Bilel Derbel and Ke Li and Hui Li and Xiaodong Li and Sa{\'u}l Zapotecas and Qingfu Zhang and St{\'e}phane Doncieux and Richard Duro and Joshua Auerbach and Harold {de Vladar} and Antonio J. Fernandez-Leiva and JJ Merelo and Pedro A. Castillo-Valdivieso and David Camacho-Fernandez and Francisco {Chavez de la O} and Ozgur Akman and Khulood Alyahya and Juergen Branke and Kevin Doherty and Jonathan Fieldsend and Giuseppe Carlo Marano and Nikos D. Lagaros and Koichi Nakayama and Chika Oshima and Stefan Wagner and Michael Affenzeller and Boris Naujoks and Vanessa Volz and Tea Tusar and Pascal Kerschke and Riyad Alshammari and Tokunbo Makanju and Brad Alexander and Saemundur O. Haraldsson and Markus Wagner and John R. Woodward and Shin Yoo and John McCall and Nayat Sanchez-Pi and Luis Mart{\'i} and Danilo Vasconcellos and Masaya Nakata and Anthony Stein and Nadarajen Veerapen and Arnaud Liefooghe and S{\'e}bastien Verel and Gabriela Ochoa and Stephen L. Smith and Stefano Cagnoni and Robert M. Patton and William {La Cava} and Randal Olson and Patryk Orzechowski and Ryan Urbanowicz and Ivanoe {De Falco} and Antonio {Della Cioppa} and Ernesto Tarantino and Umberto Scafuri and P. G. M. Baltus and Giovanni Iacca and Ahmed Hallawa and Anil Yaman and Alma Rahat and Handing Wang and Yaochu Jin and David Walker and Richard Everson and Akira Oyama and Koji Shimoyama and Hemant Kumar and Kazuhisa Chiba and Pramudita Satria Palar}, isbn13 = {978-1-4503-5764-7}, pages = {1914--1917}, address = {Kyoto, Japan}, url = {http://doi.acm.org/10.1145/3205651.3208220}, doi = {doi:10.1145/3205651.3208220}, pdf = {http://cs.hamilton.edu/~thelmuth/Pubs/2018-GECCO-workshop-lexicase-specialization.pdf}, publisher = {ACM}, publisher_address = {New York, NY, USA}, month = {15-19 } # jul, organisation = {SIGEVO}, notes = {Also known as \cite{3208220} GECCO-2018 A Recombination of the 27th International Conference on Genetic Algorithms (ICGA-2018) and the 23rd Annual Genetic Programming Conference (GP-2018)}, doi-url = {http://dx.doi.org/10.1145/3205651.3208220} }
@inproceedings{Pantridge:2017:GECCOa, author = {Edward Pantridge and Thomas Helmuth and Nicholas Freitag McPhee and Lee Spector}, title = {On the Difficulty of Benchmarking Inductive Program Synthesis Methods}, booktitle = {Proceedings of the Genetic and Evolutionary Computation Conference Companion}, series = {GECCO '17}, year = {2017}, isbn13 = {978-1-4503-4939-0}, address = {Berlin, Germany}, pages = {1589--1596}, size = {8 pages}, url = {http://doi.acm.org/10.1145/3067695.3082533}, doi = {doi:10.1145/3067695.3082533}, pdf = {http://cs.hamilton.edu/~thelmuth/Pubs/2017-GECCO-workshop-benchmarking-program-synthesis.pdf}, acmid = {3082533}, publisher = {ACM}, publisher_address = {New York, NY, USA}, keywords = {genetic algorithms, genetic programming, benchmarking, inductive program synthesis, machine learning}, month = {15-19 } # jul, abstract = {A variety of inductive program synthesis (IPS) techniques have recently been developed, emerging from different areas of computer science. However, these techniques have not been adequately compared on general program synthesis problems. In this paper we compare several methods on problems requiring solution programs to handle various data types, control structures, and numbers of outputs. The problem set also spans levels of abstraction; some would ordinarily be approached using machine code or assembly language, while others would ordinarily be approached using high-level languages. The presented comparisons are focused on the possibility of success; that is, on whether the system can produce a program that passes all tests, for all training and unseen testing inputs. The compared systems are Flash Fill, MagicHaskeller, TerpreT, and two forms of genetic programming. The two genetic programming methods chosen were PushGP and Grammar Guided Genetic Programming. The results suggest that PushGP and, to an extent, TerpreT and Grammar Guided Genetic Programming are more capable of finding solutions than the others, albeit at a higher computational cost. A more salient observation is the difficulty of comparing these methods due to drastically different intended applications, despite the common goal of program synthesis.}, notes = {Also known as \cite{Pantridge:2017:DBI:3067695.3082533} GECCO-2017 A Recombination of the 26th International Conference on Genetic Algorithms (ICGA-2017) and the 22nd Annual Genetic Programming Conference (GP-2017)}, doi-url = {http://dx.doi.org/10.1145/3067695.3082533} }
@inproceedings{Helmuth:2016:GECCOcomp, author = {Thomas Helmuth and Nicholas Freitag McPhee and Lee Spector}, title = {Effects of Lexicase and Tournament Selection on Diversity Recovery and Maintenance}, booktitle = {GECCO '16 Companion: Proceedings of the Companion Publication of the 2016 Annual Conference on Genetic and Evolutionary Computation}, year = {2016}, noeditor = {Tobias Friedrich and Frank Neumann and Andrew M. Sutton and Martin Middendorf and Xiaodong Li and Emma Hart and Mengjie Zhang and Youhei Akimoto and Peter A. N. Bosman and Terry Soule and Risto Miikkulainen and Daniele Loiacono and Julian Togelius and Manuel Lopez-Ibanez and Holger Hoos and Julia Handl and Faustino Gomez and Carlos M. Fonseca and Heike Trautmann and Alberto Moraglio and William F. Punch and Krzysztof Krawiec and Zdenek Vasicek and Thomas Jansen and Jim Smith and Simone Ludwig and JJ Merelo and Boris Naujoks and Enrique Alba and Gabriela Ochoa and Simon Poulding and Dirk Sudholt and Timo Koetzing}, isbn13 = {978-1-4503-4323-7}, pages = {983--990}, address = {Denver, Colorado, USA}, month = {20-24 } # jul, keywords = {genetic algorithms, genetic programming}, organisation = {SIGEVO}, doi = {doi:10.1145/2908961.2931657}, url = {http://doi.acm.org/10.1145/2908961.2931657}, pdf = {http://cs.hamilton.edu/~thelmuth/Pubs/2016-GECCO-workshop-diversity-maintenance.pdf}, publisher = {ACM}, publisher_address = {New York, NY, USA}, abstract = {In genetic programming systems, parent selection algorithms select the programs from which offspring will be produced by random variation and recombination. While most parent selection algorithms select programs on the basis of aggregate performance on multiple test cases, the lexicase selection algorithm considers each test case individually, in random order, for each parent selection event. Prior work has shown that lexicase selection can produce both more diverse populations and more solutions when applied to several hard problems. Here we examine the effects of lexicase selection, compared to those of the more traditional tournament selection algorithm, on population error diversity using two program synthesis problems. We conduct experiments in which the same initial population is used to start multiple runs, each using a different random number seed. The initial populations are extracted from genetic programming runs, and fall into three categories: high diversity populations, low diversity populations, and populations that occur after diversity crashes. The reported data shows that lexicase selection can maintain high error diversity and also that it can re-diversify less-diverse populations, while tournament selection consistently produces lower diversity.}, notes = {Distributed at GECCO-2016.}, doi-url = {http://dx.doi.org/10.1145/2908961.2931657} }
@inproceedings{Spector:2016:GECCOcomp, author = {Lee Spector and Nicholas Freitag McPhee and Thomas Helmuth and Maggie M. Casale and Julian Oks}, title = {Evolution Evolves with Autoconstruction}, booktitle = {GECCO '16 Companion: Proceedings of the Companion Publication of the 2016 Annual Conference on Genetic and Evolutionary Computation}, year = {2016}, noeditor = {Tobias Friedrich and Frank Neumann and Andrew M. Sutton and Martin Middendorf and Xiaodong Li and Emma Hart and Mengjie Zhang and Youhei Akimoto and Peter A. N. Bosman and Terry Soule and Risto Miikkulainen and Daniele Loiacono and Julian Togelius and Manuel Lopez-Ibanez and Holger Hoos and Julia Handl and Faustino Gomez and Carlos M. Fonseca and Heike Trautmann and Alberto Moraglio and William F. Punch and Krzysztof Krawiec and Zdenek Vasicek and Thomas Jansen and Jim Smith and Simone Ludwig and JJ Merelo and Boris Naujoks and Enrique Alba and Gabriela Ochoa and Simon Poulding and Dirk Sudholt and Timo Koetzing}, isbn13 = {978-1-4503-4323-7}, pages = {1349--1356}, address = {Denver, Colorado, USA}, month = {20-24 } # jul, keywords = {genetic algorithms, genetic programming}, organisation = {SIGEVO}, doi = {doi:10.1145/2908961.2931727}, url = {http://doi.acm.org/10.1145/2908961.2931727}, pdf = {http://cs.hamilton.edu/~thelmuth/Pubs/2016-GECCO-workshop-autoconstruction.pdf}, publisher = {ACM}, publisher_address = {New York, NY, USA}, abstract = {In autoconstructive evolutionary algorithms, individuals implement not only candidate solutions to specified computational problems, but also their own methods for variation of offspring. This makes it possible for the variation methods to themselves evolve, which could, in principle, produce a system with an enhanced capacity for adaptation and superior problem solving power. Prior work on autoconsruction has explored a range of system designs and their evolutionary dynamics, but it has not solved hard problems. Here we describe a new approach that can indeed solve at least some hard problems. We present the key components of this approach, including the use of linear genomes for hierarchically structured programs, a diversity-maintaining parent selection algorithm, and the enforcement of diversification constraints on offspring. We describe a software synthesis benchmark problem that our new approach can solve, and we present visualizations of data from single successful runs of autoconstructive vs. non-autoconstructive systems on this problem. While anecdotal, the data suggests that variation methods, and therefore significant aspects of the evolutionary process, evolve over the course of the autoconstructive runs.}, notes = {Distributed at GECCO-2016.}, doi-url = {http://dx.doi.org/10.1145/2908961.2931727} }
@inproceedings{McPhee:2016:GECCOcomp, author = {Nicholas Freitag McPhee and Maggie M. Casale and Mitchell Finzel and Thomas Helmuth and Lee Spector}, title = {Visualizing Genetic Programming Ancestries}, booktitle = {GECCO '16 Companion: Proceedings of the Companion Publication of the 2016 Annual Conference on Genetic and Evolutionary Computation}, year = {2016}, isbn13 = {978-1-4503-4323-7}, pages = {1419--1426}, keywords = {genetic algorithms, genetic programming, pushGP, liner genetic programming, Clojush, lexicase selection}, month = {20-24 } # jul, organisation = {SIGEVO}, address = {Denver, Colorado, USA}, doi = {doi:10.1145/2908961.2931741}, url = {http://doi.acm.org/10.1145/2908961.2931741}, pdf = {http://cs.hamilton.edu/~thelmuth/Pubs/2016-GECCO-workshop-visualizing-ancestries.pdf}, publisher = {ACM}, publisher_address = {New York, NY, USA}, size = {8 pages}, abstract = {Previous work has demonstrated the utility of graph databases as a tool for collecting, analysing, and visualizing ancestry in evolutionary computation runs. That work focused on sections of individual runs, whereas this paper illustrates the application of these ideas on the entirety of large runs (up to three hundred thousand individuals) and combinations of multiple runs. Here we use these tools to generate graphs showing all the ancestors of successful individuals from a variety of stack-based genetic programming runs on software synthesis problems. These graphs highlight important moments in the evolutionary process. They also allow us to compare the dynamics for successful and unsuccessful runs. As well as displaying these full ancestry graphs, we use a variety of standard techniques such as size, colour, pattern, labelling, and opacity to visualize other important information such as fitness, which genetic operators were used, and the distance between parent and child genomes. While this generates an extremely rich visualization, the amount of data can also be somewhat overwhelming, so we also explore techniques for filtering these graphs that allow us to better understand the key dynamics.}, notes = {Titan graph database. Tinkerpop query tools. Graphviz dot. Mutation and crossover. Hyperselection events. Replace space with newline benchmark. p1420 'uses restricted Boltzmann machines (RBMs) to compress the 200 error values into 24-bit RGB color values' p1423 'presence of an individual could have had..impact..even if..never contributed genetic material' p1423 'unfilter' p1426 future dynamic tools. My pdf reader barfs Slides https://www.slideshare.net/NicMcPhee/visualizing-genetic-programming-ancestries Cites \cite{series/sci/BurlacuAWKK15}}, doi-url = {http://dx.doi.org/10.1145/2908961.2931741} }
@inproceedings{Liskowski:2015:GECCOcomp, author = {Pawel Liskowski and Krzysztof Krawiec and Thomas Helmuth and Lee Spector}, title = {Comparison of Semantic-aware Selection Methods in Genetic Programming}, booktitle = {GECCO 2015 Semantic Methods in Genetic Programming (SMGP'15) Workshop}, year = {2015}, noeditor = {Colin Johnson and Krzysztof Krawiec and Alberto Moraglio and Michael O'Neill}, isbn13 = {978-1-4503-3488-4}, keywords = {genetic algorithms, genetic programming, Semantic Methods in (SMGP'15) Workshop}, pages = {1301--1307}, month = {11-15 } # jul, organisation = {SIGEVO}, address = {Madrid, Spain}, url = {http://doi.acm.org/10.1145/2739482.2768505}, doi = {doi:10.1145/2739482.2768505}, pdf = {http://cs.hamilton.edu/~thelmuth/Pubs/2015-GECCO-semantic-aware-selection.pdf}, publisher = {ACM}, publisher_address = {New York, NY, USA}, abstract = {This study investigates the performance of several semantic-aware selection methods for genetic programming (GP). In particular, we consider methods that do not rely on complete GP semantics (i.e., a tuple of outputs produced by a program for fitness cases (tests)), but on binary outcome vectors that only state whether a given test has been passed by a program or not. This allows us to relate to test-based problems commonly considered in the domain of coevolutionary algorithms and, in prospect, to address a wider range of practical problems, in particular the problems where desired program output is unknown (e.g., evolving GP controllers). The selection methods considered in the paper include implicit fitness sharing (ifs), discovery of derived objectives (doc), lexicase selection (lex), as well as a hybrid of the latter two. These techniques, together with a few variants, are experimentally compared to each other and to conventional GP on a battery of discrete benchmark problems. The outcomes indicate superior performance of lex and ifs, with some variants of doc showing certain potential.}, notes = {Also known as \cite{2768505} Distributed at GECCO-2015.}, doi-url = {http://dx.doi.org/10.1145/2739482.2768505} }
@inproceedings{Helmuth:2013:GECCOcomp, author = {Thomas Helmuth and Lee Spector}, title = {Evolving a digital multiplier with the {PushGP} genetic programming system}, booktitle = {GECCO '13 Companion: Proceeding of the fifteenth annual conference companion on Genetic and evolutionary computation conference companion}, year = {2013}, noeditor = {Christian Blum and Enrique Alba and Thomas Bartz-Beielstein and Daniele Loiacono and Francisco Luna and Joern Mehnen and Gabriela Ochoa and Mike Preuss and Emilia Tantar and Leonardo Vanneschi and Kent McClymont and Ed Keedwell and Emma Hart and Kevin Sim and Steven Gustafson and Ekaterina Vladislavleva and Anne Auger and Bernd Bischl and Dimo Brockhoff and Nikolaus Hansen and Olaf Mersmann and Petr Posik and Heike Trautmann and Muhammad Iqbal and Kamran Shafi and Ryan Urbanowicz and Stefan Wagner and Michael Affenzeller and David Walker and Richard Everson and Jonathan Fieldsend and Forrest Stonedahl and William Rand and Stephen L. Smith and Stefano Cagnoni and Robert M. Patton and Gisele L. Pappa and John Woodward and Jerry Swan and Krzysztof Krawiec and Alexandru-Adrian Tantar and Peter A. N. Bosman and Miguel Vega-Rodriguez and Jose M. Chaves-Gonzalez and David L. Gonzalez-Alvarez and Sergio Santander-Jimenez and Lee Spector and Maarten Keijzer and Kenneth Holladay and Tea Tusar and Boris Naujoks}, isbn13 = {978-1-4503-1964-5}, keywords = {genetic algorithms, genetic programming}, pages = {1627--1634}, month = {6-10 } # jul, organisation = {SIGEVO}, address = {Amsterdam, The Netherlands}, url = {http://dl.acm.org/citation.cfm?doid=2464576.2466814}, doi = {doi:10.1145/2464576.2466814}, pdf = {http://cs.hamilton.edu/~thelmuth/Pubs/digital-multiplier-GECCO-2013.pdf}, publisher = {ACM}, publisher_address = {New York, NY, USA}, abstract = {A recent article on benchmark problems for genetic programming suggested that researchers focus attention on the digital multiplier problem, also known as the multiple output multiplier problem, in part because it is scalable and in part because the requirement of multiple outputs presents challenges for some forms of genetic programming [20]. Here we demonstrate the application of stack-based genetic programming to the digital multiplier problem using the PushGP genetic programming system, which evolves programs expressed in the stack-based Push programming language. We demonstrate the use of output instructions and argue that they provide a natural mechanism for producing multiple outputs in a stack-based genetic programming context. We also show how two recent developments in PushGP dramatically improve the performance of the system on the digital multiplier problem. These developments are the ULTRA genetic operator, which produces offspring via Uniform Linear Transformation with Repair and Alternation [12], and lexicase selection, which selects parents according to performance on cases considered sequentially in random order [11]. Our results using these techniques show not only their utility, but also the utility of the digital multiplier problem as a benchmark problem for genetic programming research. The results also demonstrate the exibility of stack-based genetic programming for solving problems with multiple outputs and for serving as a platform for experimentation with new genetic programming techniques.}, notes = {Also known as \cite{2466814} Distributed at GECCO-2013.}, doi-url = {http://dx.doi.org/10.1145/2464576.2466814} }
@inproceedings{Helmuth:2011:GECCOcomp, author = {Thomas Helmuth and Lee Spector and Brian Martin}, title = {Size-based tournaments for node selection}, booktitle = {GECCO 2011 Graduate students workshop}, year = {2011}, noeditor = {Miguel Nicolau}, isbn13 = {978-1-4503-0690-4}, keywords = {genetic algorithms, genetic programming}, pages = {799--802}, month = {12-16 } # jul, organisation = {SIGEVO}, address = {Dublin, Ireland}, url = {http://dl.acm.org/citation.cfm?doid=2001858.2002095}, doi = {doi:10.1145/2001858.2002095}, pdf = {http://hampshire.edu/lspector/pubs/node-selection-gecco2011-cited.pdf}, erratum = {http://cs.hamilton.edu/~thelmuth/node-selection-gecco-2011.html}, publisher = {ACM}, publisher_address = {New York, NY, USA}, abstract = {In genetic programming, the reproductive operators of crossover and mutation both require the selection of nodes from the reproducing individuals. Both unbiased random selection and Koza 90/10 mechanisms remain popular, despite their arbitrary natures and a lack of evidence for their effectiveness. It is generally considered problematic to select from all nodes with a uniform distribution, since this causes terminal nodes to be selected most of the time. This can limit the complexity of program fragments that can be exchanged in crossover, and it may also lead to code bloat when leaf nodes are replaced with larger new subtrees during mutation. We present a new node selection method that selects nodes based on a tournament, from which the largest participating subtree is selected. We show this method of size-based tournaments improves performance on three standard test problems with no increases in code bloat as compared to unbiased and Koza 90/10 selection methods.}, notes = {Also known as \cite{2002095} Distributed on CD-ROM at GECCO-2011. ACM Order Number 910112.}, doi-url = {http://dx.doi.org/10.1145/2001858.2002095} }
@inproceedings{Spector:2019:GPTP, author = {Edward Pantridge and Thomas Helmuth and Lee Spector}, title = {Comparison of Linear Genome Representations For Software Synthesis}, booktitle = {Genetic Programming Theory and Practice XVII}, year = {2019}, editor = {Wolfgang Banzhaf and Erik Goodman and Leigh Sheneman and Leonardo Trujillo and Bill Worzel}, pages = {255--274}, address = {East Lansing, MI, USA}, month = {16-19 } # may, publisher = {Springer}, keywords = {genetic algorithms, genetic programming}, isbn13 = {978-3-030-39957-3}, url = {https://link.springer.com/chapter/10.1007/978-3-030-39958-0_13}, doi = {doi:10.1007/978-3-030-39958-0_13}, pdf = {http://cs.hamilton.edu/~thelmuth/Pubs/2019-GPTP-linear-genomes-representations.pdf}, abstract = {In many genetic programming systems, the program variation and execution processes operate on different program representations. The representations on which variation operates are referred to as genomes. Unconstrained linear genome representations can provide a variety of advantages, including reduced complexity of program generation, variation, simplification and serialization operations. The Plush genome representation, which uses epigenetic markers on linear genomes to express nonlinear structures, has supported the production of state-of-the-art results in program synthesis with the PushGP genetic programming system. Here we present a new, simpler, non-epigenetic alternative to Plush, called Plushy, that appears to maintain all of the advantages of Plush while providing additional benefits. These results illustrate the virtues of unconstrained linear genome representations more generally, and may be transferable to genetic programming systems that target different languages for evolved programs.}, notes = {Part of \cite{Banzhaf:2019:GPTP}, published after the workshop}, doi-url = {http://dx.doi.org/10.1007/978-3-030-39958-0_13} }
@inproceedings{Troise:2017:GPTP, author = {Sarah Anne Troise and Thomas Helmuth}, title = {Lexicase Selection with Weighted Shuffle}, booktitle = {Genetic Programming Theory and Practice XV}, editor = {Wolfgang Banzhaf and Randal S. Olson and William Tozier and Rick Riolo}, year = {2017}, series = {Genetic and Evolutionary Computation}, pages = {89--104}, address = {University of Michigan in Ann Arbor, USA}, month = may # { 18--20}, organisation = {the Center for the Study of Complex Systems}, publisher = {Springer}, keywords = {genetic algorithms, genetic programming}, isbn13 = {978-3-319-90511-2}, url = {https://link.springer.com/chapter/10.1007/978-3-319-90512-9_6}, doi = {doi:10.1007/978-3-319-90512-9_6}, abstract = {Semantic-aware methods in genetic programming take into account information about programs performances across a set of test cases. Lexicase parent selection, a semantic-aware selection, randomly shuffles the list of test cases and places more emphasis on those test cases that randomly appear earlier in the ordering than those that appear later in the ordering. In this work, we explore methods for weighting this shuffling of test cases to give some test cases more influence over selection than others. We design and test a variety of weighted shuffle algorithms and methods for weighting test cases. In experiments on two program synthesis benchmark problems, we find that none of these methods significantly outperform regular lexicase selection. We analyse these results by examining how each method affects population diversity, and find that those methods that perform much worse also have significantly lower diversity.}, notes = {GPTP 2017, Part of \cite{Banzhaf:2017:GPTP} published after the workshop in 2018}, doi-url = {http://dx.doi.org/10.1007/978-3-319-90512-9_6}, pdf = {http://cs.hamilton.edu/~thelmuth/Pubs/2017-GPTP-weighted-lexicase.pdf} }
@inproceedings{Spector:2017:GPTP, author = {Lee Spector and William {La Cava} and Saul Shanabrook and Thomas Helmuth and Edward Pantridge}, title = {Relaxations of Lexicase Parent Selection}, booktitle = {Genetic Programming Theory and Practice XV}, editor = {Wolfgang Banzhaf and Randal S. Olson and William Tozier and Rick Riolo}, year = {2017}, series = {Genetic and Evolutionary Computation}, pages = {105--120}, address = {University of Michigan in Ann Arbor, USA}, month = may # { 18--20}, organisation = {the Center for the Study of Complex Systems}, publisher = {Springer}, keywords = {genetic algorithms, genetic programming}, isbn13 = {978-3-319-90511-2}, url = {https://link.springer.com/chapter/10.1007/978-3-319-90512-9_7}, doi = {doi:10.1007/978-3-319-90512-9_7}, abstract = {In a genetic programming system, the parent selection algorithm determines which programs in the evolving population will be used as the material out of which new programs will be constructed. The lexicase parent selection algorithm chooses a parent by considering all test cases, individually, one at a time, in a random order, to reduce the pool of possible parent programs. Lexicase selection is ordinarily strict, in that a program can only be selected if it has the best error in the entire population on the first test case considered, and the best error relative to all other programs that remain in the pool each time it is reduced. This strictness may exclude high-quality candidates from consideration for parenthood, and hence from exploration by the evolutionary process. In this chapter we describe and present results of four variants of lexicase selection that relax these strict constraints: epsilon lexicase selection, random threshold lexicase selection, MADCAP epsilon lexicase selection, and truncated lexicase selection. We present the results of experiments with genetic programming systems using these and other parent selection algorithms on symbolic regression and software synthesis problems. We also briefly discuss the relations between lexicase selection and work on many-objective optimization, and the implications of these considerations for future work on parent selection in genetic programming.}, notes = {GPTP 2017, Part of \cite{Banzhaf:2017:GPTP} published after the workshop in 2018}, doi-url = {http://dx.doi.org/10.1007/978-3-319-90512-9_7}, pdf = {http://cs.hamilton.edu/~thelmuth/Pubs/2017-GPTP-relaxed-lexicase.pdf} }
@inproceedings{Helmuth:2016:GPTP, author = {Thomas Helmuth and Lee Spector and Nicholas Freitag McPhee and Saul Shanabrook}, title = {Linear Genomes for Structured Programs}, booktitle = {Genetic Programming Theory and Practice XIV}, year = {2016}, editor = {Rick Riolo and Bill Worzel and Brian Goldman and Bill Tozier}, pages = {85--100}, address = {Ann Arbor, USA}, month = {19-21 } # may, publisher = {Springer}, keywords = {genetic algorithms, genetic programming, Uniform variation, linear genomes, Push, Plush}, isbn13 = {978-3-319-97087-5}, url = {http://cs.hamilton.edu/~thelmuth/Pubs/2016-GPTP-plush.pdf}, url = {https://www.springer.com/us/book/9783319970875}, doi = {doi:10.1007/978-3-319-97088-2_6}, size = {15 pages}, abstract = {In most genetic programming systems, candidate solution programs themselves serve as the genetic material upon which variation operators act. However, because of the hierarchical structure of computer programs, and the syntactic constraints that they must obey, it is difficult to implement variation operators that affect different parts of programs with uniform probability. This can have detrimental effects on evolutionary search. In prior work, structured programs were linearised prior to variation in order to facilitate uniformity, but this necessitated syntactic repair after variation, which reintroduced non-uniformities. In this chapter we describe a new approach that uses linear genomes, from which structured programs are expressed only for the purpose of fitness testing. We present the new approach in detail and show how it facilitates both uniform variation and the evolution of programs with meaningful structure.}, notes = {Part of \cite{Tozier:2016:GPTP} published after the workshop}, doi-url = {http://dx.doi.org/10.1007/978-3-319-97088-2_6}, pdf = {http://cs.hamilton.edu/~thelmuth/Pubs/2016-GPTP-plush.pdf} }
@inproceedings{McPhee:2016:GPTP, author = {Nicholas Freitag McPhee and Mitchell D. Finzel and Maggie M. Casale and Thomas Helmuth and Lee Spector}, title = {A detailed analysis of a {PushGP} run}, booktitle = {Genetic Programming Theory and Practice XIV}, year = {2016}, editor = {Rick Riolo and Bill Worzel and Brian Goldman and Bill Tozier}, pages = {65--83}, address = {Ann Arbor, USA}, month = {19-21 } # may, publisher = {Springer}, keywords = {genetic algorithms, genetic programming, PushGP, ancestry graph, lineage, inheritance}, isbn13 = {978-3-319-97087-5}, url = {https://www.springer.com/us/book/9783319970875}, doi = {doi:10.1007/978-3-319-97088-2_5}, pdf = {http://cs.hamilton.edu/~thelmuth/Pubs/2016-GPTP-full-run-analysis.pdf}, abstract = {In evolutionary computation runs there is a great deal of data that could be saved and analysed. This data is often put aside, however, in favour of focusing on the final outcomes, typically captured and presented in the form of summary statistics and performance plots. Here we examine a genetic programming run in detail and trace back from the solution to determine how it was derived. To visualize this genetic programming run, the ancestry graph is extracted, running from the solution(s) in the final generation up to their ancestors in the initial random population. The key instructions in the solution are also identified, and a genetic ancestry graph is constructed, a subgraph of the ancestry graph containing only those individuals contributed genetic information (or instructions) to the solution. This visualization and our ability to trace these key instructions throughout the run allowed us to identify general inheritance patterns and key evolutionary moments in this run.}, notes = {Part of \cite{Tozier:2016:GPTP} published after the workshop}, doi-url = {http://dx.doi.org/10.1007/978-3-319-97088-2_5} }
@inproceedings{Helmuth:2015:GPTP, author = {Thomas Helmuth and Nicholas Freitag McPhee and Lee Spector}, title = {Lexicase Selection For Program Synthesis: {A} Diversity Analysis}, booktitle = {Genetic Programming Theory and Practice XIII}, year = {2015}, noeditor = {Rick Riolo and William P. Worzel and M. Kotanchek and A. Kordon}, series = {Genetic and Evolutionary Computation}, address = {Ann Arbor, USA}, month = may, publisher = {Springer}, keywords = {genetic algorithms, genetic programming, Lexicase selection, diversity, tournament selection, implicit fitness sharing}, isbn13 = {978-3-319-34223-8}, pdf = {http://cs.hamilton.edu/~thelmuth/Pubs/2015-GPTP-lexicase-diversity-analysis.pdf}, url = {http://www.springer.com/us/book/9783319342214}, size = {16 pages}, abstract = {Lexicase selection is a selection method for evolutionary computation in which individuals are selected by filtering the population according to performance on test cases, considered in random order. When used as the parent selection method in genetic programming, lexicase selection has been shown to provide significant improvements in problem-solving power. In this chapter we investigate the reasons for the success of lexicase selection, focusing on measures of population diversity. We present data from eight program synthesis problems and compare lexicase selection to tournament selection and selection based on implicit fitness sharing. We conclude that lexicase selection does indeed produce more diverse populations, which helps to explain the utility of lexicase selection for program synthesis.}, notes = {Replace Space With Newline, Syllables, String Lengths Backwards, Negative To Zero, Double Letters, Scrabble Score, Checksum, Count Odds. http://cscs.umich.edu/gptp-workshops/ Part of \cite{Riolo:2015:GPTP} Published after the workshop in 2016} }
@inproceedings{McPhee:2015:GPTP, author = {Nicholas Freitag McPhee and David Donatucci and Thomas Helmuth}, title = {Using Graph Databases to Explore Genetic Programming Run Dynamics}, booktitle = {Genetic Programming Theory and Practice XIII}, year = {2015}, noeditor = {Rick Riolo and William P. Worzel and M. Kotanchek and A. Kordon}, series = {Genetic and Evolutionary Computation}, address = {Ann Arbor, USA}, month = may, publisher = {Springer}, keywords = {genetic algorithms, genetic programming}, isbn13 = {978-3-319-34223-8}, url = {http://www.springer.com/us/book/9783319342214}, pdf = {http://cs.hamilton.edu/~thelmuth/Pubs/2015-GPTP-graph-database.pdf}, notes = {http://cscs.umich.edu/gptp-workshops/ Part of \cite{Riolo:2015:GPTP} Published after the workshop in 2016} }
@inproceedings{Kannappan:2014:GPTP, author = {Karthik Kannappan and Lee Spector and Moshe Sipper and Thomas Helmuth and William La Cava and Jake Wisdom and Omri Bernstein}, title = {Analyzing a Decade of Human-Competitive (``{HUMIE}'') Winners: What Can We Learn?}, booktitle = {Genetic Programming Theory and Practice XII}, year = {2014}, noeditor = {Rick Riolo and William P. Worzel and Mark Kotanchek}, series = {Genetic and Evolutionary Computation}, pages = {149--166}, address = {Ann Arbor, USA}, month = {8-10 } # may, publisher = {Springer}, keywords = {genetic algorithms, genetic programming, HUMIES, Evolutionary Computation, Human Competitive}, isbn13 = {978-3-319-16029-0}, url = {http://link.springer.com/chapter/10.1007%2F978-3-319-16030-6_9}, doi = {doi:10.1007/978-3-319-16030-6_9}, pdf = {http://faculty.hampshire.edu/lspector/pubs/Anaylzing_the_Humies.pdf}, size = {16 pages}, abstract = {Techniques in evolutionary computation (EC) have improved significantly over the years, leading to a substantial increase in the complexity of problems that can be solved by EC-based approaches. The HUMIES awards at the Genetic and Evolutionary Computation Conference are designed to recognise work that has not just solved some problem via techniques from evolutionary computation, but has produced a solution that is demonstrably human-competitive. In this chapter, we take a look across the winners of the past 10 years of the HUMIES awards, and analyse them to determine whether there are specific approaches that consistently show up in the HUMIE winners. We believe that this analysis may lead to interesting insights regarding prospects and strategies for producing further human competitive results.}, notes = {http://cscs.umich.edu/gptp-workshops/ Part of \cite{Riolo:2014:GPTP} published after the workshop in 2015}, doi-url = {http://dx.doi.org/10.1007/978-3-319-16030-6_9} }
@incollection{Spector:2013:GPTP, author = {Lee Spector and Thomas Helmuth}, title = {Uniform Linear Transformation with Repair and Alternation in Genetic Programming}, booktitle = {Genetic Programming Theory and Practice XI}, year = {2013}, series = {Genetic and Evolutionary Computation}, noeditor = {Rick Riolo and Jason H. Moore and Mark Kotanchek}, publisher = {Springer}, chapter = {8}, pages = {137--153}, address = {Ann Arbor, USA}, month = {9-11 } # may, keywords = {genetic algorithms, genetic programming, Uniform mutation, Uniform crossover, ULTRA, Push, PushGP, Drug bioavailability problem, Pagie-1 problem, Factorial regression, Boolean multiplexer problem}, isbn13 = {978-1-4939-0374-0}, url = {http://link.springer.com/chapter/10.1007%2F978-1-4939-0375-7_8}, doi = {doi:10.1007/978-1-4939-0375-7_8}, pdf = {http://faculty.hampshire.edu/lspector/pubs/spector-gptp-2013-preprint-erratum.pdf}, abstract = {Several genetic programming researchers have argued for the utility of genetic operators that act uniformly. By act uniformly we mean two specific things: that the probability of an inherited program component being modified during inheritance is independent of the size and shape of the parent programs beyond the component in question; and that pairs of parents are combined in ways that allow arbitrary combinations of components from each parent to appear in the child. Uniform operators described in previous work have had limited utility, however, because of a mismatch between the relevant notions of uniformity and the hierarchical structure and variable sizes of many genetic programming representations. In this chapter we describe a new genetic operator, ULTRA, which incorporates aspects of both mutation and crossover and acts approximately uniformly across programs of variable sizes and structures. ULTRA treats hierarchical programs as linear sequences and includes a repair step to ensure that syntax constraints are satisfied after variation. We show that on the drug bioavailability and Pagie-1 benchmark problems ULTRA produces significant improvements both in problem-solving power and in program size relative to standard operators. Experiments with factorial regression and with the Boolean 6-multiplexer problem demonstrate that ULTRA can manipulate programs that make use of hierarchical structure, but also that it is not always beneficial. The demonstrations evolve programs in the Push programming language, which makes repair particularly simple, but versions of the technique should be applicable in other genetic programming systems as well.}, notes = {http://cscs.umich.edu/gptp-workshops/ Part of \cite{Riolo:2013:GPTP} published after the workshop in 2013}, doi-url = {http://dx.doi.org/10.1007/978-1-4939-0375-7_8} }
@incollection{Helmuth:2012:GPTP, author = {Thomas Helmuth and Lee Spector}, title = {Evolving {SQL} Queries from Examples with Developmental Genetic Programming}, booktitle = {Genetic Programming Theory and Practice X}, year = {2012}, series = {Genetic and Evolutionary Computation}, noeditor = {Rick Riolo and Ekaterina Vladislavleva and Marylyn D. Ritchie and Jason H. Moore}, publisher = {Springer}, chapter = {1}, pages = {1--14}, address = {Ann Arbor, USA}, month = {12-14 } # may, keywords = {genetic algorithms, genetic programming, Data mining, Classification, SQL, Push, PushGP}, isbn13 = {978-1-4614-6845-5}, url = {http://link.springer.com/chapter/10.1007%2F978-1-4614-6846-2_1}, doi = {doi:10.1007/978-1-4614-6846-2_1}, pdf = {http://hampshire.edu/lspector/pubs/gptp-2012-preprint.pdf}, abstract = {Large databases are becoming ever more ubiquitous, as are the opportunities for discovering useful knowledge within them. Evolutionary computation methods such as genetic programming have previously been applied to several aspects of the problem of discovering knowledge in databases. The more specific task of producing human-comprehensible SQL queries has several potential applications but has thus far been explored only to a limited extent. In this chapter we show how developmental genetic programming can automatically generate SQL queries from sets of positive and negative examples. We show that a developmental genetic programming system can produce queries that are reasonably accurate while excelling in human comprehensibility relative to the well-known C5.0 decision tree generation system.}, notes = {part of \cite{Riolo:2012:GPTP} published after the workshop in 2013}, doi-url = {http://dx.doi.org/10.1007/978-1-4614-6846-2_1} }
@incollection{Spector:2011:GPTP, author = {Lee Spector and Kyle Harrington and Brian Martin and Thomas Helmuth}, title = {What's in an Evolved Name? The Evolution of Modularity via Tag-Based Reference}, booktitle = {Genetic Programming Theory and Practice IX}, year = {2011}, noeditor = {Rick Riolo and Ekaterina Vladislavleva and Jason H. Moore}, series = {Genetic and Evolutionary Computation}, address = {Ann Arbor, USA}, month = {12-14 } # may, publisher = {Springer}, chapter = {1}, pages = {1--16}, keywords = {genetic algorithms, genetic programming, modularity, names, tags, stack-based genetic programming, Push programming language, PushGP}, isbn13 = {978-1-4614-1769-9}, url = {http://link.springer.com/chapter/10.1007%2F978-1-4614-1770-5_1}, pdf = {http://hampshire.edu/lspector/pubs/spector-gptp11-preprint.pdf}, doi = {doi:10.1007/978-1-4614-1770-5_1}, size = {18 pages}, abstract = {Programming languages provide a variety of mechanisms to associate names with values, and these mechanisms play a central role in programming practice. For example, they allow multiple references to the same storage location or function in different parts of a complex program. By contrast, the representations used in current genetic programming systems provide few if any naming mechanisms, and it is therefore generally not possible for evolved programs to use names in sophisticated ways. we describe a new approach to names in genetic programming that is based on John Holland's concept of tags. We demonstrate the use of tag-based names, we describe some of the ways in which they may help to extend the power and reach of genetic programming systems and we look at the ways that tag-based names are actually used in an evolved program that solves a robot navigation problem.}, notes = {section 1. 'Grammars of most programming languages fail to be fully context free because name definitions and uses must match...' Push in C++, Java, JavaScript, Python, Common Lips, Clojure, Scheme, Erlang and R. Tags both for values (variables) and code (functions). untag. scoping rules? dirt-sensing robot 15 modules (table 1-1). See also \cite{Spector:2011:GECCO}. Part of \cite{Riolo:2011:GPTP}}, affiliation = {Cognitive Science, Hampshire College, Amherst, MA 01002, USA}, doi-url = {http://dx.doi.org/10.1007/978-1-4614-1770-5_1} }
@inproceedings{Helmuth:2020:GECCOcomp, author = {Thomas Helmuth and Amr Abdelhady}, title = {Benchmarking Parent Selection for Program Synthesis by Genetic Programming}, year = {2020}, noeditor = {Richard Allmendinger and Hugo Terashima Marin and Efren Mezura Montes and Thomas Bartz-Beielstein and Bogdan Filipic and Ke Tang and David Howard and Emma Hart and Gusz Eiben and Tome Eftimov and William {La Cava} and Boris Naujoks and Pietro Oliveto and Vanessa Volz and Thomas Weise and Bilel Derbel and Ke Li and Xiaodong Li and Saul Zapotecas and Qingfu Zhang and Rui Wang and Ran Cheng and Guohua Wu and Miqing Li and Hisao Ishibuchi and Jonathan Fieldsend and Ozgur Akman and Khulood Alyahya and Juergen Branke and John R. Woodward and Daniel R. Tauritz and Marco Baioletti and Josu Ceberio Uribe and John McCall and Alfredo Milani and Stefan Wagner and Michael Affenzeller and Bradley Alexander and Alexander (Sandy) Brownlee and Saemundur O. Haraldsson and Markus Wagner and Nayat Sanchez-Pi and Luis Marti and Silvino {Fernandez Alzueta} and Pablo {Valledor Pellicer} and Thomas Stuetzle and Matthew Johns and Nick Ross and Ed Keedwell and Herman Mahmoud and David Walker and Anthony Stein and Masaya Nakata and David Paetzel and Neil Vaughan and Stephen Smith and Stefano Cagnoni and Robert M. Patton and Ivanoe {De Falco} and Antonio {Della Cioppa} and Umberto Scafuri and Ernesto Tarantino and Akira Oyama and Koji Shimoyama and Hemant Kumar Singh and Kazuhisa Chiba and Pramudita Satria Palar and Alma Rahat and Richard Everson and Handing Wang and Yaochu Jin and Erik Hemberg and Riyad Alshammari and Tokunbo Makanju and Fuijimino-shi and Ivan Zelinka and Swagatam Das and Ponnuthurai Nagaratnam and Roman Senkerik}, isbn13 = {9781450371278}, publisher = {ACM}, publisher_address = {New York, NY, USA}, url = {https://doi.org/10.1145/3377929.3389987}, pdf = {http://cs.hamilton.edu/~thelmuth/Pubs/2020-GECCO-poster-benchmarking-parent-selection.pdf}, doi = {doi:10.1145/3377929.3389987}, booktitle = {Proceedings of the 2020 Genetic and Evolutionary Computation Conference Companion}, pages = {237--238}, size = {2 pages}, keywords = {genetic algorithms, genetic programming, parent selection, benchmark, program synthesis}, series = {GECCO '20}, month = jul # { 8-12}, organisation = {SIGEVO}, notes = {Also known as \cite{10.1145/3377929.3389987} GECCO-2020 A Recombination of the 29th International Conference on Genetic Algorithms (ICGA) and the 25th Annual Genetic Programming Conference (GP)}, doi-url = {http://dx.doi.org/10.1145/3377929.3389987} }
@inproceedings{Helmuth:2020:GECCOcompa, author = {Thomas Helmuth and Lee Spector and Edward Pantridge}, title = {Counterexample-Driven Genetic Programming without Formal Specifications}, year = {2020}, noeditor = {Richard Allmendinger and Hugo Terashima Marin and Efren Mezura Montes and Thomas Bartz-Beielstein and Bogdan Filipic and Ke Tang and David Howard and Emma Hart and Gusz Eiben and Tome Eftimov and William {La Cava} and Boris Naujoks and Pietro Oliveto and Vanessa Volz and Thomas Weise and Bilel Derbel and Ke Li and Xiaodong Li and Saul Zapotecas and Qingfu Zhang and Rui Wang and Ran Cheng and Guohua Wu and Miqing Li and Hisao Ishibuchi and Jonathan Fieldsend and Ozgur Akman and Khulood Alyahya and Juergen Branke and John R. Woodward and Daniel R. Tauritz and Marco Baioletti and Josu Ceberio Uribe and John McCall and Alfredo Milani and Stefan Wagner and Michael Affenzeller and Bradley Alexander and Alexander (Sandy) Brownlee and Saemundur O. Haraldsson and Markus Wagner and Nayat Sanchez-Pi and Luis Marti and Silvino {Fernandez Alzueta} and Pablo {Valledor Pellicer} and Thomas Stuetzle and Matthew Johns and Nick Ross and Ed Keedwell and Herman Mahmoud and David Walker and Anthony Stein and Masaya Nakata and David Paetzel and Neil Vaughan and Stephen Smith and Stefano Cagnoni and Robert M. Patton and Ivanoe {De Falco} and Antonio {Della Cioppa} and Umberto Scafuri and Ernesto Tarantino and Akira Oyama and Koji Shimoyama and Hemant Kumar Singh and Kazuhisa Chiba and Pramudita Satria Palar and Alma Rahat and Richard Everson and Handing Wang and Yaochu Jin and Erik Hemberg and Riyad Alshammari and Tokunbo Makanju and Fuijimino-shi and Ivan Zelinka and Swagatam Das and Ponnuthurai Nagaratnam and Roman Senkerik}, isbn13 = {9781450371278}, publisher = {ACM}, publisher_address = {New York, NY, USA}, url = {https://doi.org/10.1145/3377929.3389983}, pdf = {http://cs.hamilton.edu/~thelmuth/Pubs/2020-GECCO-poster-counterexample-gp.pdf}, doi = {doi:10.1145/3377929.3389983}, booktitle = {Proceedings of the 2020 Genetic and Evolutionary Computation Conference Companion}, pages = {239--240}, size = {2 pages}, keywords = {genetic algorithms, genetic programming, counterexamples, program synthesis}, series = {GECCO '20}, month = jul # { 8-12}, organisation = {SIGEVO}, notes = {Also known as \cite{10.1145/3377929.3389983} GECCO-2020 A Recombination of the 29th International Conference on Genetic Algorithms (ICGA) and the 25th Annual Genetic Programming Conference (GP)}, doi-url = {http://dx.doi.org/10.1145/3377929.3389983} }
@inproceedings{Helmuth:2020:GECCOcompb, author = {Thomas Helmuth and Edward Pantridge and Grace Woolson and Lee Spector}, title = {Transfer Learning of Genetic Programming Instruction Sets}, year = {2020}, noeditor = {Richard Allmendinger and Hugo Terashima Marin and Efren Mezura Montes and Thomas Bartz-Beielstein and Bogdan Filipic and Ke Tang and David Howard and Emma Hart and Gusz Eiben and Tome Eftimov and William {La Cava} and Boris Naujoks and Pietro Oliveto and Vanessa Volz and Thomas Weise and Bilel Derbel and Ke Li and Xiaodong Li and Saul Zapotecas and Qingfu Zhang and Rui Wang and Ran Cheng and Guohua Wu and Miqing Li and Hisao Ishibuchi and Jonathan Fieldsend and Ozgur Akman and Khulood Alyahya and Juergen Branke and John R. Woodward and Daniel R. Tauritz and Marco Baioletti and Josu Ceberio Uribe and John McCall and Alfredo Milani and Stefan Wagner and Michael Affenzeller and Bradley Alexander and Alexander (Sandy) Brownlee and Saemundur O. Haraldsson and Markus Wagner and Nayat Sanchez-Pi and Luis Marti and Silvino {Fernandez Alzueta} and Pablo {Valledor Pellicer} and Thomas Stuetzle and Matthew Johns and Nick Ross and Ed Keedwell and Herman Mahmoud and David Walker and Anthony Stein and Masaya Nakata and David Paetzel and Neil Vaughan and Stephen Smith and Stefano Cagnoni and Robert M. Patton and Ivanoe {De Falco} and Antonio {Della Cioppa} and Umberto Scafuri and Ernesto Tarantino and Akira Oyama and Koji Shimoyama and Hemant Kumar Singh and Kazuhisa Chiba and Pramudita Satria Palar and Alma Rahat and Richard Everson and Handing Wang and Yaochu Jin and Erik Hemberg and Riyad Alshammari and Tokunbo Makanju and Fuijimino-shi and Ivan Zelinka and Swagatam Das and Ponnuthurai Nagaratnam and Roman Senkerik}, isbn13 = {9781450371278}, publisher = {ACM}, publisher_address = {New York, NY, USA}, url = {https://doi.org/10.1145/3377929.3389988}, pdf = {http://cs.hamilton.edu/~thelmuth/Pubs/2020-GECCO-poster-transfer-learning-instruction-sets.pdf}, doi = {doi:10.1145/3377929.3389988}, booktitle = {Proceedings of the 2020 Genetic and Evolutionary Computation Conference Companion}, pages = {241--242}, size = {2 pages}, keywords = {genetic algorithms, genetic programming, transfer learning, instruction set, PushGP}, series = {GECCO '20}, month = jul # { 8-12}, organisation = {SIGEVO}, notes = {Also known as \cite{10.1145/3377929.3389988} GECCO-2020 A Recombination of the 29th International Conference on Genetic Algorithms (ICGA) and the 25th Annual Genetic Programming Conference (GP)}, doi-url = {http://dx.doi.org/10.1145/3377929.3389988} }
@inproceedings{McPhee:2017:GECCOa, author = {Nicholas Freitag McPhee and Thomas Helmuth and Lee Spector}, title = {Using Algorithm Configuration Tools to Optimize Genetic Programming Parameters: A Case Study}, booktitle = {Proceedings of the Genetic and Evolutionary Computation Conference Companion}, series = {GECCO '17}, year = {2017}, isbn13 = {978-1-4503-4939-0}, address = {Berlin, Germany}, pages = {243--244}, size = {2 pages}, url = {http://doi.acm.org/10.1145/3067695.3076097}, doi = {doi:10.1145/3067695.3076097}, pdf = {http://cs.hamilton.edu/~thelmuth/Pubs/2017-GECCO-poster-SMAC-and-PushGP.pdf}, acmid = {3076097}, publisher = {ACM}, publisher_address = {New York, NY, USA}, keywords = {genetic algorithms, genetic programming, SMAC, parameter optimization, pushGP, software synthesis}, month = {15-19 } # jul, abstract = {We use Sequential Model-based Algorithm Configuration (SMAC) to optimize a group of parameters for PushGP, a stack-based genetic programming system, for several software synthesis problems. Applying SMAC to one particular problem leads to marked improvements in the success rate and the speed with which a solution was found for that problem. Applying these {"}tuned{"} parameters to four additional problems, however, only improved performance on one, and substantially reduced performance on another. This suggests that SMAC is overfitting, tuning the parameters in ways that are highly problem specific, and raises doubts about the value of using these {"}tuned{"} parameters on previously unsolved problems. Efforts to use SMAC to optimize PushGP parameters on other problems have been less successful due to a combination of long PushGP run times and low success rates, which make it hard for SMAC to acquire enough information in a reasonable amount of time.}, notes = {Also known as \cite{McPhee:2017:UAC:3067695.3076097} GECCO-2017 A Recombination of the 26th International Conference on Genetic Algorithms (ICGA-2017) and the 22nd Annual Genetic Programming Conference (GP-2017)}, doi-url = {http://dx.doi.org/10.1145/3067695.3076097} }
@inproceedings{McPhee:2017:GECCO, author = {Nicholas Freitag McPhee and Maggie M. Casale and Mitchell Finzel and Thomas Helmuth and Lee Spector}, title = {Visualizing Genetic Programming Ancestries Using Graph Databases}, booktitle = {Proceedings of the Genetic and Evolutionary Computation Conference Companion}, series = {GECCO '17}, year = {2017}, isbn13 = {978-1-4503-4939-0}, address = {Berlin, Germany}, pages = {245--246}, size = {2 pages}, url = {http://doi.acm.org/10.1145/3067695.3075617}, doi = {doi:10.1145/3067695.3075617}, pdf = {http://cs.hamilton.edu/~thelmuth/Pubs/2017-GECCO-poster-ancestries.pdf}, acmid = {3075617}, publisher = {ACM}, publisher_address = {New York, NY, USA}, keywords = {genetic algorithms, genetic programming, ancestry, graph database, visualization}, month = {15-19 } # jul, notes = {Also known as \cite{McPhee:2017:VGP:3067695.3075617} GECCO-2017 A Recombination of the 26th International Conference on Genetic Algorithms (ICGA-2017) and the 22nd Annual Genetic Programming Conference (GP-2017)}, doi-url = {http://dx.doi.org/10.1145/3067695.3075617} }
@inproceedings{Spector:2014:GECCOcomp, author = {Lee Spector and Thomas Helmuth}, title = {Effective simplification of evolved push programs using a simple, stochastic hill-climber}, booktitle = {GECCO Comp '14: Proceedings of the 2014 conference companion on Genetic and evolutionary computation companion}, year = {2014}, noeditor = {Christian Igel and Dirk V. Arnold and Christian Gagne and Elena Popovici and Anne Auger and Jaume Bacardit and Dimo Brockhoff and Stefano Cagnoni and Kalyanmoy Deb and Benjamin Doerr and James Foster and Tobias Glasmachers and Emma Hart and Malcolm I. Heywood and Hitoshi Iba and Christian Jacob and Thomas Jansen and Yaochu Jin and Marouane Kessentini and Joshua D. Knowles and William B. Langdon and Pedro Larranaga and Sean Luke and Gabriel Luque and John A. W. McCall and Marco A. {Montes de Oca} and Alison Motsinger-Reif and Yew Soon Ong and Michael Palmer and Konstantinos E. Parsopoulos and Guenther Raidl and Sebastian Risi and Guenther Ruhe and Tom Schaul and Thomas Schmickl and Bernhard Sendhoff and Kenneth O. Stanley and Thomas Stuetzle and Dirk Thierens and Julian Togelius and Carsten Witt and Christine Zarges}, isbn13 = {978-1-4503-2881-4}, keywords = {genetic algorithms, genetic programming: Poster}, pages = {147--148}, month = {12-16 } # jul, organisation = {SIGEVO}, address = {Vancouver, BC, Canada}, url = {http://doi.acm.org/10.1145/2598394.2598414}, doi = {doi:10.1145/2598394.2598414}, pdf = {http://cs.hamilton.edu/~thelmuth/Pubs/simplification-GECCO-2014.pdf}, publisher = {ACM}, publisher_address = {New York, NY, USA}, abstract = {Genetic programming systems often produce programs that include unnecessary code. This is undesirable for several reasons, including the burdens that overly-large programs put on end-users for program interpretation and maintenance. The problem is exacerbated by recently developed techniques, such as genetic programming with geometric semantic crossover, that tend to produce enormous programs. Methods for automatically simplifying evolved programs are therefore of interest, but automatic simplification is non-trivial in the context of traditional program representations with unconstrained function sets. Here we show how evolved programs expressed in the stack-based Push programming language can be automatically and reliably simplified using a simple, stochastic hill-climber. We demonstrate and quantitatively characterise this simplification process on programs evolved to solve four non-trivial genetic programming problems with qualitatively different function sets.}, notes = {Also known as \cite{2598414} Distributed at GECCO-2014.}, doi-url = {http://dx.doi.org/10.1145/2598394.2598414} }
@inproceedings{Helmuth:2012:GECCOcomp, author = {Thomas Helmuth and Lee Spector}, title = {Empirical investigation of size-based tournaments for node selection in genetic programming}, booktitle = {GECCO Companion '12: Proceedings of the fourteenth international conference on Genetic and evolutionary computation conference companion}, year = {2012}, noeditor = {Terry Soule and Anne Auger and Jason Moore and David Pelta and Christine Solnon and Mike Preuss and Alan Dorin and Yew-Soon Ong and Christian Blum and Dario Landa Silva and Frank Neumann and Tina Yu and Aniko Ekart and Will Browne and Tim Kovacs and Man-Leung Wong and Clara Pizzuti and Jon Rowe and Tobias Friedrich and Giovanni Squillero and Nicolas Bredeche and Stephen Smith and Alison Motsinger-Reif and Jose Lozano and Martin Pelikan and Silja Meyer-Nienberg and Christian Igel and Greg Hornby and Rene Doursat and Steve Gustafson and Gustavo Olague and Shin Yoo and John Clark and Gabriela Ochoa and Gisele Pappa and Fernando Lobo and Daniel Tauritz and Jurgen Branke and Kalyanmoy Deb}, isbn13 = {978-1-4503-1178-6}, keywords = {genetic algorithms, Genetic programming: Poster}, pages = {1485--1486}, month = {7-11 } # jul, organisation = {SIGEVO}, address = {Philadelphia, Pennsylvania, USA}, url = {http://dl.acm.org/citation.cfm?doid=2330784.2331004}, doi = {doi:10.1145/2330784.2331004}, pdf = {http://hampshire.edu/lspector/pubs/p1485.pdf}, publisher = {ACM}, publisher_address = {New York, NY, USA}, abstract = {In genetic programming systems, genetic operators must select nodes upon which to act; the method by which they select nodes influences problem solving performance and possibly also code growth. A recently proposed node selection method using size-based tournaments has been shown to have potential, but variations of the method have not been studied systematically. Here we extend the ideas of size-based tournaments and test how they can improve problem-solving performance. We consider allowing tournament size to depend on whether we are selecting nodes within donors for crossover, recipients for crossover, or targets of mutation. We also consider tournaments that bias selection toward smaller trees rather than larger trees. We find that differentiating between donors and recipients is probably not worthwhile and that size 2 tournaments perform near-optimally.}, notes = {Also known as \cite{2331004} Distributed at GECCO-2012. ACM Order Number 910122.}, doi-url = {http://dx.doi.org/10.1145/2330784.2331004} }
@inproceedings{Spector:2011:FSE:2001858.2001932, author = {Spector, Lee and Helmuth, Thomas and Harrington, Kyle}, title = {Fecundity and Selectivity in Evolutionary Computation}, booktitle = {Proceedings of the 13th Annual Conference Companion on Genetic and Evolutionary Computation}, series = {GECCO '11}, year = {2011}, isbn = {978-1-4503-0690-4}, location = {Dublin, Ireland}, pages = {129--130}, numpages = {2}, url = {http://doi.acm.org/10.1145/2001858.2001932}, doi = {10.1145/2001858.2001932}, pdf = {http://hampshire.edu/lspector/pubs/decimation-gecco2011-cited.pdf}, acmid = {2001932}, month = {12-16 } # jul, organisation = {SIGEVO}, address = {Dublin, Ireland}, publisher = {ACM}, publisher_address = {New York, NY, USA}, keywords = {deb's deceptive problem, decimation, fecundity, selection, truncation} }
@inproceedings{Helmuth:2021:GECCOtutorial:lexicase, author = {Thomas Helmuth and Bill La Cava}, title = {Lexicase Selection}, year = {2021}, publisher = {ACM}, publisher_address = {New York, NY, USA}, url = {}, pdf = {}, doi = {}, booktitle = {Proceedings of the 2021 Genetic and Evolutionary Computation Conference Companion}, series = {GECCO '21}, month = jul # { 10-14}, organisation = {SIGEVO} }
@phdthesis{Helmuth:thesis, author = {Thomas Helmuth}, title = {General Program Synthesis from Examples Using Genetic Programming with Parent Selection Based on Random Lexicographic Orderings of Test Cases}, school = {College of Information and Computer Sciences, University of Massachusetts Amherst}, year = {2015}, address = {USA}, month = sep, keywords = {genetic algorithms, genetic programming, lexicase}, url = {https://web.cs.umass.edu/publication/details.php?id=2398}, pdf = {https://web.cs.umass.edu/publication/docs/2015/UM-CS-PhD-2015-005.pdf}, size = {159 pages}, abstract = {Software developers routinely create tests before writing code, to ensure that their programs fulfill their requirements. Instead of having human programmers write the code to meet these tests, automatic program synthesis systems can create programs to meet specifications without human intervention, only requiring examples of desired behavior. In the long-term, we envision using genetic programming to synthesize large pieces of software. This dissertation takes steps toward this goal by investigating the ability of genetic programming to solve introductory computer science programming problems. We present a suite of 29 benchmark problems intended to test general program synthesis systems, which we systematically selected from sources of introductory computer science programming problems. This suite is suitable for experiments with any program synthesis system driven by input/output examples. Unlike existing benchmarks that concentrate on constrained problem domains such as list manipulation, symbolic regression, or Boolean functions, this suite contains general programming problems that require a range of programming constructs, such as multiple data types and data structures, control flow statements, and I/O. The problems encompass a range of difficulties and requirements as necessary to thoroughly assess the capabilities of a program synthesis system. Besides describing the specifications for each problem, we make recommendations for experimental protocols and statistical methods to use with the problems. This dissertation's second contribution is an investigation of behaviour-based parent selection in genetic programming, concentrating on a new method called lexicase selection. Most parent selection techniques aggregate errors from test cases to compute a single scalar fitness value; lexicase selection instead treats test cases separately, never comparing error values of different test cases. This property allows it to select parents that specialise on some test cases even if they perform poorly on others. We compare lexicase selection to other parent selection techniques on our benchmark suite, showing better performance for lexicase selection. After observing that lexicase selection increases exploration of the search space while also increasing exploitation of promising programs, we conduct a range of experiments to identify which characteristics of lexicase selection influence its utility.}, notes = {UM-CS-Phd-2015-005 Supervised by Lee Spector GP discussion list 27 Sep 2015: https://groups.yahoo.com/neo/groups/genetic_programming/conversations/messages/6785} }
@techreport{Helmuth:2015006:UM, author = {Thomas Helmuth and Lee Spector}, title = {Detailed Problem Descriptions for General Program Synthesis Benchmark Suite}, institution = {Computer Science, University of Massachusetts, Amherst}, year = {2015}, type = {Technical Report}, number = {UM-CS-2015-006}, month = {June}, keywords = {program synthesis, genetic programming, benchmarks}, url = {https://web.cs.umass.edu/publication/details.php?id=2387}, pdf = {https://web.cs.umass.edu/publication/docs/2015/UM-CS-2015-006.pdf}, size = {17 pages}, abstract = {Recent interest in the development and use of non-trivial benchmark problems for genetic programming research has highlighted the scarcity of general program synthesis (also called ``traditional programming'') benchmark problems. We present a suite of $29$ general program synthesis benchmark problems systematically selected from sources of introductory computer science programming problems. This suite is suitable for experiments with any program synthesis system driven by input/output examples. We present results from illustrative experiments using our reference implementation of the problems in the PushGP genetic programming system. This technical report provides sufficient detail of the problems and our reference implementation for researchers to implement and attempt to solve these problems in other synthesis systems. The results show that the problems in the suite vary in difficulty and can be useful for assessing the capabilities of a program synthesis system.} }
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