Papers, Presentations, etc.

2024

• Leveraging reviewer experience in code review comment generation, Hong Yi Lin, Patanamon Thongtanunam, Christoph Treude, Michael W. Godfrey, Chunhua Liu, Wachiraphan Charoenwet, arXiv:2409.10959 [cs.SE].
• "Reevaluating the defect proneness of atoms of confusion in Java systems", Albert Guoshuai Shi, Farshad Kazemi, Michael W. Godfrey, and Shane McIntosh, 18th ACM/IEEE Intl. Symp. on Empirical Software Engineering and Measurement (ESEM-24), 20-24 October, Barcelona, Spain. [Acceptance rate: 34/139 or 24%]
• "Studying the impact of risk assessment analytics on risk awareness and code review performance", Xueyao Yu, Filipe R. Cogo, Shane McIntosh, and Michael W. Godfrey, Empirical Software Engineering (EMSE) 29(46), February 2024.
• "What is an app store? The software engineering perspective", Wenhan Cosmos Zhu, Sebastian Proksch, Daniel M. German, Michael W. Godfrey, Li Li, Shane McIntosh, Empirical Software Engineering (EMSE) 29(35), January 2024.

2023

• "Continuous alignment between software architecture design and development in CI/CD pipelines", Davide Taibi, Yuanfang Cai, Ingo Weber, Mehdi Mirakhorli, Michael W. Godfrey, John T. Stough, and Patrizio Pelliccione, book chapter in Software Architecture Research Roadmaps from the Community, Patrizio Pelliccione, Rick Kazman, Ingo Weber, Anna Liu (eds), Springer, October 2023.
• "A better way to teach software architecture", Rick Kazman, Yuanfang Cai, Michael W. Godfrey, Cesare Pautasso, and Anna Liu, book chapter in Software Architecture Research Roadmaps from the Community, Patrizio Pelliccione, Rick Kazman, Ingo Weber, Anna Liu (eds), Springer, October 2023.
• "Bash in the wild: Language usage, code smells, and bugs", Yiwen Dong, Zheyang Li, Yongqiang Tian, Chengnian Sun, Michael W. Godfrey, and Meiyappan Nagappan, ACM Trans. on Software Engineering and Methodology (ACM-TOSEM) 32(1), presented at the Journal First track at ICSE 2023, Melbourne AU, May 2023.

2022

• "An empirical study of question discussions on Stack Overflow", Wenhan Zhu, Haoxiang Zhang, Ahmed E. Hassan, Michael W. Godfrey, Empirical Software Engineering (EMSE) 27(148), presented at the Journal First track at ICSE 2023, Melbourne AU, May 2023.
• "Ddocter: Extracting constraints from documentation to test deep learning API functions", Danning Xie, Yitong Li, Mijung Kim, Hung Viet Pham, Lin Tan, Xiangyu Zhang, Michael W. Godfrey, Proc. of the 31st Intl. Symp. on Software Testing and Analysis (ISSTA-22), held online July 2022. [Acceptance rate: 61/250 or 24%]

2021

• "Mea culpa: How developers fix their own simple bugs differently from other developers" (MSR challenge track paper), Wenhan Cosmos Zhu and Michael W. Godfrey, Proc. of the 18th ACM/IEEE Intl. Conf. on Mining Software Repositories (MSR-21), 17–19 May 2021.
• "Sometimes, cloning is a sound design decision!", Michael W. Godfrey and Cory J. Kapser, book chapter in Code Clone Analysis: Researches, Tools, and Practices, edited by Katsuro Inoue and Chanchal K. Roy, Springer, Singapore, 2021.

2020

• "mel: Model Extractor Language for extracting facts from models", Robert Hackman, Joanne M. Atlee, Alistair Finn Hackett, Michael W. Godfrey, Proc. of the 23rd Intl. Conf. on Model-Driven Engineering Languages and Systems (MODELS-20), 18-23 October 2020, Montreal. [Acceptance rate: 23/87 or 26%]
  

2019

• "A study on the effects of exception usage in open-source C++ systems", Kirsten Bradley and Michael Godfrey, Proc. of the 19th IEEE Intl. Working Conf. on Source Code Analysis and Manipulation (SCAM-19), Cleveland, OH, 30 September - 1 October, 2019. [Acceptance rate: 29/53 or 40%]
• "Detecting feature-interaction symptoms in automotive software using lightweight analysis", Bryan Muscedere, Robert Hackman, Davood Anbarnam, Joanne Atlee, Ian J. Davis, and Michael W. Godfrey, Proc. of 26th IEEE Intl. Conf. on Software Analysis, Evolution and Reengineering (SANER-19), Hangzhou, China, February 24-27, 2019. [Acceptance rate: 40/148 or 27% for full papers]
• "A comparison of bugs across the iOS and Android platforms of two open source cross platform browser apps", Wajdi M. Aljedaani, Meiyappan Nagappan, Bram Adams, and Michael W. Godfrey, Proc. of the 6th IEEE/ACM Intl. Conf. on Mobile Software Engineering and Systems (MOBILESoft-19), Montreal, May 2019.

2018

• "Studying pull request merges: A case study of Shopify's Active Merchant", Oleksii Kononenko, Tresa Rose, Olga Baysal, Michael Godfrey, Dennis Theisen, Bart de Water, Proc. of the 40th ACM/IEEE Intl. Conf. on Software Engineering, track on Software Engineering in Practice (ICSE-SEIP), Gothenberg, Sweden, 27 May – 3 June 2018. [Acceptance rate: 31/133 or 24% for full papers in this track]

2017

• "On-demand developer documentation", Martin P. Robillard, Andrian Marcus, Christoph Treude, Gabriele Bavota, Oscar Chaparro, Neil Ernst, Marco Aurelio Gerosa, Michael Godfrey, Michele Lanza, Mario Linares-Vasquez, Gail Murphy, Laura Moreno, David Shepherd, and Edmund Wong, New Ideas and Emerging Results (NIER) track in Proc. of the 33rd IEEE Intl. Conference on Software Maintenance and Evolution (ICSME-17), Shanghai, China, 20–22 September 2017.

2016

• "On the evolution of operating systems and software ecosystems", invited talk given at Law OS: The Evolution and Complexity of Legal and Regulatory Systems, the Santa Fe Institue's Annual Board of Trustees and Applied Complexity Network Symposium, 3–5 November 2016, Santa Fe, NM.
• "Investigating technical and non-technical factors influencing modern code review", Olga Baysal, Oleksii Kononenko, Reid Holmes, Michael W. Godfrey, Empirical Software Engineering 21(6), June 2016.
  • This is an extended version of our WCRE 2013 paper.
• "Connecting the dots: Anomaly and discontinuity detection in large-scale systems", Haroon Malik, Ian Davis, Michael W. Godfrey, Douglas Neuse, and Serge Manskovskii, Journal of Ambient Intelligence and Humanized Computing, 7(4), August 2016, 14pp.
• "'Cloning considered harmful' considered harmful: A look back", Most Influential Paper talk (from WCRE 2006), Osaka, Japan, March 2016.
• "Swimming with the data: Looking for trouble on the open seas", keynote presentation, 4th Intl. Workshop on Open and Original Problems in Software Language Engineering (OOPSLE-16), Osaka, Japan, March 2016.
• "Why provenance matters", Michael W. Godfrey, a chapter in the book Perspectives on Data Science for Software Engineering, Tim Menzies, Laurie Williams, and Thomas Zimmermann (eds.), Morgan Kaufmann, 2016.
• "An empirical study on the practice of maintaining object-relational mapping code in Java systems", Tse-Hsun Chen, Weiyi Shang, Jinqiu Yang, Ahmed E Hassan, Michael W Godfrey, Mohamed Nasser, Parminder Flora, Proc. of the 2016 IEEE Intl. Working Conference on Mining Software Repositories (MSR-16), Austin TX, May 2016. [Acceptance rate: 36/103 or 27% for full papers]
• "Code review quality: How developers see it", Oleksii Kononenko, Olga Baysal, and Michael W. Godfrey, Proc. of the 38th ACM/IEEE Intl. Conference on Software Engineering (ICSE), Austin, TX, May 2016. [Acceptance rate: 101/530 or 19% for full papers]

2015

• "Listening to code clones or, Philately will get you everywhere", keynote presentation, 9th Intl. Workshop on Software Clones (IWSC-15), March 6, 2015.
• "Synthesizing knowledge from software development artifacts", Olga Baysal, Oleksii Kononenko, Reid Holmes, and Michael W. Godfrey, a chapter in the book The Art and Science of Analyzing Software Data, Christian Bird, Tim Menzies, and Thomas Zimmermann (eds.), Morgan Kaufmann, 2015.
• "Investigating code review quality: Do people and participation matter?", Oleksii Kononenko, Olga Baysal, Latifa Guerrouj, Yaxin Cao, and Michael W. Godfrey, Proc. of the 31st IEEE Intl. Conference on Software Maintenance and Evolution (ICSME-15), Bremen, Germany, Sept. 29-Oct. 1, 2015. [Acceptance rate: 32/148 or 22% for full papers]
• "Going green: An exploratory analysis of energy-related questions" (MSR challenge track short paper), Haroon Malik, Peng Zhao, and Michael W. Godfrey, Proc. of the 2015 IEEE Working Conference on Mining Software Repositories (MSR-15), Florence, Italy, May 2015. [Acceptance rate: 14/21 or 67% for papers in this track]
• "Recommending posts concerning API issues in developer Q&A sites", Wei Wang, Haroon Malik, and Michael W. Godfrey, Proc. of the 2015 IEEE Working Conference on Mining Software Repositories (MSR-15), Florence, Italy, May 2015. [Acceptance rate: 32/106 or 30% for full papers]
• "Specifying anomalous data spaces", Ian J. Davis, Michael W. Godfrey, Douglas Neuse, Serge Mankovskii.
• "Understanding software artifact provenance", Michael W. Godfrey, invited paper to a journal special issue on the theme of "New Ideas and Emerging Results in Understanding Software" honouring the career of Paul Klint of CWI, Science of Computer Programming, 97(1), January 2015.

2014

• "Detecting discontinuities in large-scale systems", Haroon Malik, Ian J. Davis, Michael W. Godfrey, Douglas Neuse, Serge Mankovskii, Proc.of the ACM/IEEE Intl. Conference on Utility and Cloud Computing (UCC-14), December 8-11, London UK. [Acceptance rate: 38/198 or 19% for full papers]
• "Compiling clones: What happens?" (short paper), Oleksii Kononenko, Cheng Zhang, and Michael W. Godfrey, Proc. of the 30th IEEE Intl. Conference on Software Maintenance and Evolution (ICSME-14), Early Research Achievements (ERA) track, Victoria BC, Oct 1-3, 2014. [Acceptance rate: 28/77 or 36% for papers in this track]
• "Recommending clones for refactoring using design, context, and history", Wei Wang and Michael W. Godfrey, Proc. of the 30th IEEE Intl. Conference on Software Maintenance and Evolution (ICSME-14), Oct 1-3, 2014. [Acceptance rate: 40/210 or 19% for full papers]
• "No issue left behind: Reducing information overload in issue tracking", Olga Baysal, Reid Holmes, and Michael W. Godfrey, Proc. of the 22nd ACM SIGSOFT Intl. Symp. on the Foundations of Software Engineering (FSE-14), November 16-22, Hong Kong. [Acceptance rate: 61/273 or 22% for full papers]
• "On the evolution of Lehman's Laws", Michael W. Godfrey and Daniel M. German, invited paper in a special issue of the Journal of Software: Evolution and Process (JSEP) honouring the career of Manny Lehman, 26(7), July 2014.
• "Mining modern repositories with Elasticsearch" (short paper), Oleksii Kononenko, Olga Baysal, Reid Holmes, and Michael W. Godfrey, Proc. of the 11th IEEE Working Conference on Mining Software Repositories (MSR-14), Hyderabad, India, 31 May - 1 June 2014. [Acceptance rate: 10/27 or 37% for short papers]
• "DASHboards: Enhancing developer situational awareness", Oleksii Kononenko, Olga Baysal, Reid Holmes, and Michael W. Godfrey, accepted to appear as a tool demo at the 36th Intl. Conference on Software Engineering (ICSE-14), Hyderabad, India, June 2014. [Acceptance rate: 15/41 or 36.5% for papers in this track] Also, here's the short video we submitted.
• "Investigating intentional clone refactoring", Wei Wang and Michael W. Godfrey (position paper), Proc. of the 8th Intl. Workshop on Software Clones (IWSC-14), Antwerp, Belgium, 3 February 2014.
  • Wei's presentation of this won the People's Choice Award for Best Position Paper Presentation at IWSC 2014.

2013

• "Listening to big data: Philately will get you everywhere", a talk given at the 29th Crest Open Workshop on Redundancy in Software, University College London (UK), 19 November 2013. MPEG video (380MB)
• "Sharing is fun! Thoughts on open access research", Michael W. Godfrey, invited talk at ICSM 2013 panel session on open access to research data and tools.
• "Automated topic naming: Supporting cross-project analysis of software maintenance", Abram Hindle, Neil A. Ernst, Michael W. Godfrey, and John Mylopoulos. Empirical Software Engineering, 18(6), Decemeber 2013.
  • This is an extended version of our MSR-11 paper that was invited to a special issue of EMSE.
• "Software Bertillonage: Determining the provenance of software development artifacts", Julius Davies, Daniel M. German, Michael W. Godfrey, and Abram Hindle, Empirical Software Engineering, 18(6), December 2013.
  • This is an extended version of our other MSR-11 paper that was invited to a special issue of EMSE.
• "Copy-paste as a principled engineering tool", a talk given at the SoCoded developers conference , Hamburg, Germnay, based on various papers, 20 September 2013. MPEG video (250 MB)
• "Requirements specifications and recovered architectures as grounded theories", Daniel M. Berry, Michael W. Godfrey, Ric Holt, Cory J. Kapser, Isabel Ramos, Grounded Theory Review, 12(1), June 2013.
• "The influence of non-technical factors on code review", Olga Baysal, Oleksii Kononenko, Reid Holmes, and Michael W. Godfrey, Proc. of the 20th Intl. Working Conference on Reverse Engineering (WCRE-13), Koblenz, Germany, October 2013. [Acceptance rate: 38/97 or 39% for full papers]
  • This won Distinguished Paper Award for WCRE 2013; we have also been invited to prepare an extended version to be considered to appear in a special issue Empirical Software Engineering
• "Regression-based utilization prediction algorithms: An empirical investigation", I. J. Davis, H. Hemmati, R.C. Holt, M. W. Godfrey, D. Neuse, S. Mankovskii, Proc. of CASCON 2013, Markham, ON, November 2013. [Acceptance rate: 27/75 or 36% for full papers]
• "Correlating interaction coupling with static coupling -- Two exploratory studies", Lijie Zou and Michael W. Godfrey, unpublished.
• "Detecting API usage obstacles: A study of iOS and Android developer questions", (short paper for MSR challenge), Wei Wang and Michael W. Godfrey, Proc. of the 10th IEEE Intl. Working Conf. on Mining Software Repositories, San Francisco, May 2013. [Acceptance rate: 12/30 or 40% for papers in this track]
• "The MSR cookbook: Mining a decade of research", Hadi Hemmati, Sarah Nadi, Olga Baysal, Oleksii Kononenko, Wei Wang, Reid Holmes, Michael W. Godfrey, Proc. of the 10th IEEE Intl. Working Conf. on Mining Software Repositories (MSR-13), San Francisco, May 2013. [Acceptance rate: 31/81 or 38% for full papers]
• "Storm prediction in a cloud" (short paper), Ian Davis, Hadi Hemmati, Richard C. Holt, Michael W. Godfrey, Douglas Neuse, Serge Mankovskii, Proc. of the Fifth International Workshop on Principles of Engineering Service-Oriented Systems (PESOS-13), San Francisco, May 2013. [Acceptance rate 7/18 or 39% for short papers]
• "Extracting artifact lifecycle models from metadata history" (short paper), Olga Baysal, Oleksii Kononenko, Reid Holmes, and Michael W. Godfrey, Proc. of Intl. Workshop on Data Analysis Patterns in Software Engineering (DAPSE-13), San Francisco, May 2013.
• "Developer dashboards: The need for qualitative analytics", Olga Baysal, Reid Holmes, and Michael W. Godfrey, IEEE Software, 30(4), special issue on the theme "Software Analytics: So What?", July/August 2013.
• "Situational awareness: Personalizing issue tracking systems" (short paper), Olga Baysal, Reid Holmes, and Michael W. Godfrey, New Ideas and Emerging Results (NIER) track in Proc. of the 2013 Intl. Conference on Software Engineering (ICSE-13), 22-24 May 2013, San Francisco. [Acceptance rate 31/143 or 22% for papers in this track]
• "An exploratory study of the evolution of communicated information about the execution of large software systems", Weiyi Shang, Zhen Ming Jiang, Bram Adams, Ahmed E. Hassan, Michael W. Godfrey, Mohamed Nasser, Parminder Flora, accepted to appear in Journal of Software: Evolution and Process.
  • This is an extended version of the WCRE 2011 submission that won the best paper award.

2012

• "The secret life of patches: A Firefox case study", Olga Baysal, Oleksii Kononenko, Reid Holmes, and Michael W. Godfrey, Proc. of the 19th Working Conference on Reverse Engineering (WCRE-12), Kingston ON, Canada, 15-18 October 2012. [Acceptance rate: 43/118 or 36% for full papers]
• "What does control flow really look like? Eyeballing the cyclomatic complexity metric", Jurgen J. Vinju and Michael W. Godfrey. Proc. of the 12th IEEE Working Conference on Source Code Analysis and Manipulation (SCAM-12), Riva del Garda, Trento, Italy, September 2012 [Acceptance rate: 16/40 or 40% for full papers]
  • This paper was selected as one of the best of SCAM-12, and we were invited to prepare an extended version for consideration for a special issue of Journal of Software: Evolution and Process (JSEP)
• "Build system issues in multilanguage software", Andrew Neitsch, Kenny Wong, and Michael W. Godfrey. Proc. of the 28th IEEE Intl. Conference on Software Maintenance (ICSM-12), Riva del Garda, Italy, September 2012 [Acceptance rate: 46/181 or 25% for full papers]
• "An industrial case study of Coman's automated task detection algorithm: What worked, what didn't, and why", Lijie Zou and Michael W. Godfrey. Proc. of the 28th IEEE Intl. Conference on Software Maintenance (ICSM-12), Riva del Garda, Italy, September 2012 [Acceptance rate: 46/181 or 25% for full papers]
• "We have all of the clones, now what? Toward integrating clone analysis into QA" (position paper), Wei Wang and Michael W. Godfrey, Proc. of the 6th Intl. Workshop on Software Clones (IWSC-12), Zürich, Switzerland, 4 June 2012.
• "The universal repository of everything" (position paper), Niko Schwarz, Daniel German, Serge Demeyer, Michael W. Godfrey, and Douglas H. Martin.
• "Clone analysis: Just another quality validation process" (position paper), Angela Lozano, Minhaz F. Zibran, Michael W. Godfrey, and Werner Teppe.
• "Revisiting bug triage and resolution practices" (position paper), Olga Baysal, Reid Holmes, and Michael W. Godfrey, 2012 ICSE Workshop on User Evaluation for Software Engineering Researchers (USER-12), Zürich, Switzerland, 5 June 2012.
• "Mining usage data and development Artifacts", Olga Baysal, Reid Holmes and Michael W. Godfrey, Proc. of the 2012 IEEE Working Conference on Mining Software Repositories (MSR-12), Zürich, Switzerland, May 2012. [Acceptance rate: 18/64 or 28.1% for full papers]
• "Introduction to the special issue on software repository mining in 2009", Michael W. Godfrey and Jim Whitehead, Empirical Software Engineering, vol. 17, no. 4-5, August 2012.
• "Analyzing assembler to eliminate dead functions: An industrial experience", Ian J. Davis, Michael W. Godfrey, Richard C. Holt, Serge Mankovskii, and Nick Minchenko (industrial track paper), Proc. of the 16th European Conference on Software Maintenance and Re-engineering (CSMR), Szeged, Hungary, 27-30 March 2012.
• "A market-based bug allocation mechanism using predictive bug lifetime", Hadi Hosseini, Raymond Nguyen, and Michael W. Godfrey, Proc. of the 16th European Conference on Software Maintenance and Re-engineering (CSMR), Szeged, Hungary, 27-30 March 2012. [Acceptance rate: 30/108 or 27.8% for full papers]

2011

• "Squinting at the data: Investigating software entity provenance using KISS techniques", a talk given at the 16th CREST Open Workshop on Software Provenance and Product Lines at University College London in November 2011. Slides and MPEG video (220 MB), but no paper.
  • A version of this talk was also given at Eindhoven University and the 10th BENEVOL workshop around the same time, at TU-München in March 2012, at the Netherlands Forensics Instutute in April 2012.
• "An exploratory study of the evolution of communicated information about the execution of large software systems", Weiyi (Ian) Shang, Zhen Ming (Jack) Jiang, Bram Adams, Ahmed E. Hassan, Michael W. Godfrey, Mohamed Nasser, Parminder Flor, Proc. of the 18th Working Conference on Reverse Engineering (WCRE-11), Limerick, Ireland, 17-20 October 2011. [Acceptance rate: 27/104 or 25.9% for full papers]
  • This won the Best Paper Award for WCRE 2011
  • An extended version been accepted to appear in a special issue of the Journal of Software Maintenance and Evolution: Research and Practice.
• "A study of cloning in the Linux SCSI drivers", Wei Wang and Michael W. Godfrey, Proc. of the 11th Intl. IEEE Working Conference on Source Code Analysis and Manipulation (SCAM-11), Williamsburg VA, 25-26 September 2011. [Acceptance rate: 16/52 or 30.7% for full papers]
• "A tale of two browsers" (short paper for MSR challenge), Olga Baysal, Ian J. Davis, and Michael W. Godfrey, Proc. of the 2011 IEEE Working Conference on Mining Software Repositories (MSR-11), Honolulu, Hawaii, May 2011.
• "Determining the provenance of software artifacts" (position paper), Michael W. Godfrey, Julius Davies, Daniel M. German, and Abram J. Hindle, Proc. of the Fifth Intl. Workshop on Software Clones (IWSC-11), Honolulu, Hawaii, May 2011.
• "Software Bertillonage: Finding the provenance of an entity", Julius Davies, Daniel M. German, Michael W. Godfrey, and Abram J. Hindle, Proc. of the 2011 IEEE Working Conference on Mining Software Repositories (MSR-11), Honolulu, Hawaii, May 2011. [Acceptance rate: 20/61 or 32.8% for full papers]
  • This paper was selected as one of the best of MSR-11, and an extended version was accepted to appear in a special issue of Empirical Software Engineering.
  • Also, there's an MPEG video (72 MB) of a talk I gave on this topic at the COW workshop at University College London on 23 November 2010; the video quality isn't great but the audio is OK.
• "Automated topic naming to support cross-project analysis of software maintenance activities", Abram Hindle, Neil A. Ernst, Michael W. Godfrey, and John Mylopoulos, Proc. of the 2011 IEEE Working Conference on Mining Software Repositories (MSR-11), Honolulu, Hawaii, May 2011. [Acceptance rate: 20/61 or 32.8% for full papers]
  • This paper was also selected as one of the best of MSR-11, and an extended version was accepted to appear in a special issue of Empirical Software Engineering.
• "Multifractal aspects of software development" (short paper), Abram Hindle, Michael W. Godfrey and Richard C. Holt. Special short paper track on New Ideas and Emerging Results (NIER) in Proc. of 2011 Intl. Conference on Software Engineering (ICSE-11), Honolulu, Hawaii, May 2011. [Acceptance rate: 46/198 or 23% for papers in this track]

2010

• "From whence it came:  Detecting source code clones by analyzing assembler" (short paper), Ian J. Davis and Michael W. Godfrey. Proc. of the 17th Intl. Working Conference on Reverse Engineering (WCRE-10), Beverly, MA, 13–16 October 2010. [Acceptance rate 22+10/68 or 47% for short papers]
• "Software process recovery using recovered unified process views", Abram Hindle, Michael W. Godfrey and Richard C. Holt. Proc. of the 2010 IEEE Intl. Conference on Software Maintenance (ICSM-10), Timisoara, Romania, 12–18 September 2010. [Acceptance rate 36/133 or 27% for full papers]
• "Copy-paste as a principled engineering tool" (no preprint available), Michael W. Godfrey and Cory J. Kapser. This is a chapter in the book Making Software: What Really Works and Why We Believe It, by Greg Wilson and Andy Oram (eds), O'Reilly and Associates, October 2010.
• "Clone detection by exploiting assembler" (short paper), Ian J. Davis and Michael W. Godfrey. Proc. of the Fourth Intl. Workshop on Software Clones (IWSC-10), Cape Town, South Africa, May 2010.
• "Studying professional software designers and their use of abstraction" (discussion paper), Joanne M. Atlee and Michael W. Godfrey. Presented at the NSF workshop on Studying Professional Software Design, 8-10 February 2010, UC-Irvine.

2009

• Editorial for special issue of JASE on Source Code Analysis and Manipulation, Michael W. Godfrey and Bogdan Korel. Journal of Automated Software Engineering, 16(2), June 2009.
• "Reading beside the lines: Using indentation to rank revisions by complexity", Abram Hindle, Michael W. Godfrey, Richard C. Holt. Science of Computer Programming, 74(7), May 2009.
  • This is an extended version of our ICPC-08 paper that was invited to a special issue of SCP.
• "What's hot and what's not: Windowing developer topic analysis", Abram J. Hindle, Michael W. Godfrey, Richard C. Holt. Proc. of 2009 IEEE Conference on Software Maintenance (ICSM-09), Edmonton, Alberta, 20–26 September 2009. [Acceptance rate 35/162 or 22% for full papers]
• "Understanding source package organization using the hybrid model" (short paper), Xinyi Dong and Michael W. Godfrey. Proc. of 2009 IEEE Conference on Software Maintenance (ICSM-09), Edmonton, Alberta, 20–26 September 2009. [Acceptance rate (35+29)/162 or 39% for short papers]
• "Future of mining software archives: A roundtable" (invited roundtable contribution), Michael W. Godfrey, IEEE Software, 61(1), January/February 2009.
• "Automatic classification of large changes into maintenance categories", Abram J. Hindle, Daniel M. German, Michael W. Godfrey, and Richard C. Holt. Proc. of 2009 IEEE Intl. Conference on Program Comprehension (ICPC-09), 17-19 May 2009, Vancouver. [Acceptance rate 20/74 or 27% for full papers]
• "A bug you like: A framework for automated assignment of bugs" (poster paper), Olga Baysal, Michael W. Godfrey, and Robin Cohen. Proc. of 2009 IEEE Intl. Conference on Program Comprehension (ICPC-09), 17-19 May 2009, Vancouver.
• "Mining recurrent activities: Fourier analysis of change events" (short paper), Abram J. Hindle, Michael W. Godfrey, Richard C. Holt. Special short paper track on New Ideas and Emerging Results (NIER) in Proc. of the 2009 Intl. Conference on Software Engineering (ICSE-09), 20-22 May 2009, Vancouver. [Acceptance rate 21/118 or 15% for papers in this track]
• "A possible metric for semantic similarity of object-oriented analysis models and its use to estimate the predictability of OOA methods", Davor Svetinovic, Daniel M. Berry, Michael W. Godfrey, Nancy A. Day.

2008

• "The past, present, and future of software evolution", Michael W. Godfrey and Daniel M. German. Invited paper in Proc. of Frontiers of Software Maintenace track at the 2008 IEEE Intl. Conf. on Software Maintenance (ICSM-08), October 2008, Beijing, China.
• "Understanding interaction differences between newcomer and expert programmers" (short paper), Lijie Zou and Michael W. Godfrey. Proc. of the 2008 Intl. Workshop on Recommendation Systems for Software Engineering (RSSE 2008), November 2008, Atlanta.
• "Reverse engineering CAPTCHAs", Abram J. Hindle, Michael W. Godfrey, and Richard C. Holt. Proc. of the 2008 Working Conference on Reverse Engineering (WCRE-08), 15–18 October 2008, Antwerp, Belgium. [Acceptance rate 20/70 or 29% for full papers]
• 'Cloning considered harmful' considered harmful: Patterns of cloning in software", Cory J. Kapser and Michael W. Godfrey. Empirical Software Engineering (Springer), 13(6), December 2008.
  • A special issue of EMSE honouring the best papers of WCRE-06; this is an extended version of our WCRE-06 Best Paper.
• "From indentation shapes to code structures", Abram J. Hindle, Michael W. Godfrey, and Richard C. Holt. Proc. of the 8th IEEE Intl. Working Conference on Source Code Analysis and Manipulation (SCAM 2008), 28–29 September 2008, Beijing, China. [Acceptance rate: 23/61 or 38% for full papers]
• "Identifying architectural change patterns in object-oriented systems", Xinyi Dong and Michael W. Godfrey. Proc. of the 2008 IEEE Intl. Conference on Program Comprehension (ICPC-08), June 2008, Amsterdam. [Acceptance rate: 20/57 or 35% for full papers]
• "Reading beside the lines: Indentation as a proxy for complexity metrics", Abram J. Hindle, Michael W. Godfrey, and Richard C. Holt. Proc. of the 2008 IEEE Intl. Conference on Program Comprehension (ICPC-08), June 2008, Amsterdam. [Acceptance rate: 20/57 or 35% for full papers]
  • This paper was selected as one of the best at ICPC-08, and an extended version appeared in a special issue of Science of Computer Programming (Elsevier).

2007

• "Fast, cheap, and under control: Evaluating revision data reliably", a presentation given at Dagstuhl Seminar 07491 on Mining Programs and Processes Abram J. Hindle, describing work he has done under the supervision of Ric Holt and myself, December 2007.
• "All we like sheep: Cloning as a software engineering tool", an invited talk given at the ICSM-07 working session on Myths in Software Engineering, October 2007. PDF 4-up
• "Examining the effects of global data usage on software maintainability", Jason Selby, Fraser Ruffell, Mark Giesbrecht, and Michael W. Godfrey. Proc. of the 2007 Working Conference in Reverse Engineering (WCRE-07), 29-31 October 2007, Vancouver, BC. [Acceptance rate: 27/87 or 31% for full papers]
• "Don't crash twice, it ain't nice", a less-than-serious reworking of an old Dylan tune (the singer, not the programming language), originally presented in three part disharmony by Ric Holt, Hausi Müller, and myself at the April 2007 CSER meeting.
• "System-level usage dependency analysis of object-oriented systems", Xinyi Dong and Michael W. Godfrey. Proc. of the 2007 IEEE Intl. Conference on Software Maintenance (ICSM-07), 2-5 October 2007, Paris, France. [Acceptance rate: 41/214 or 21% for full papers]
• "Release pattern discovery: A case study of database systems", Abram J. Hindle, Michael W. Godfrey, and Richard C. Holt. Proc. of the 2007 IEEE Intl. Conference on Software Maintenance (ICSM-07), 2-5 October 2007, Paris, France. [Acceptance rate: 41/214 or 21% for full papers]
• "Subjectivity in clone judgment: Can we ever agree?", Cory J. Kapser, Paul Anderson, Michael W. Godfrey, Rainer Koschke, Matthias Rieger, Filip van Rysselberghe, and Peter Weißgerber, Proc. of Dagstuhl Seminar #06301, July 2007.
• "YARN: Animating software evolution", Abram J. Hindle, Zhen Ming Jiang, Walid Koleilat, Michael W. Godfrey, and Richard C. Holt. Proc. of the 2007 IEEE Intl. Workshop on Visualizing Software for Understanding and Analysis (VISSOFT-07), June 25-26, Banff, Alberta. [Acceptance rate: 15/34 or 44% for full papers] Slides
• "A hybrid program model for object-oriented reverse engineering", Xinyi Dong and Michael W. Godfrey. Proc. of the 2007 Intl. Conference on Program Comprehension (ICPC-07), 26-29 June 2007, Banff, Alberta. [Acceptance rate: 22/66 or 33% for full papers]
• "Detecting interaction coupling from task interaction histories", Lijie Zou, Michael W. Godfrey, and Ahmed E. Hassan. Proc. of the 2007 Intl. Conference on Program Comprehension (ICPC-07), 26-29 June 2007, Banff, Alberta. [Acceptance rate: 22/66 or 33% for full papers] Slides.
• "Release pattern discovery via partitioning: Methodology and case study", Abram J. Hindle, Michael W. Godfrey, Richard C. Holt. Proc. of 2007 Intl. Workshop on Mining Software Repositories (MSR-07), May 19-20, 2007, Minneapolis. [Acceptance rate: 15/39 for full papers, or 38%] Slides.
• "Adaptation, selection, and intelligent design: The forces behind software evolution", invited talk given at the 2007 Canadian University Software Engineering Conference (CUSEC-07), Montreal, 20 January 2007.
• "Unified use case statecharts: Case studies", Davor Svetinovic, Daniel M. Berry, Nancy A. Day, and Michael W. Godfrey. Requirements Engineering Journal (Springer), Vol. 12, No. 4, October 2007.

2006

• "'Cloning considered harmful' considered harmful", Cory J. Kapser and Michael W. Godfrey. Proc. of the 2006 Working Conference on Reverse Engineering (WCRE-06), 23-28 October, Benevento, Italy. [Acceptance rate: 24/84 or 29%]
  • This won the Best Paper Award for WCRE 2006, and was extended into a journal paper, accepted in 2008 to Empirical Software Engineering (see above).
  • In March 2016, this paper won the Most Influential Paper award at SANER (a merging of the WCRE and CSMR conferences).
• "An industrial case study of program artifacts viewed during maintenance tasks", Lijie Zou and Michael W. Godfrey. Proc. of the 2006 Working Conference on Reverse Engineering (WCRE-06), 23-28 October, Benevento, Italy. [Acceptance rate: 24/84 or 29%]
• "EARS: A CSER proposal", yet another not-entirely-serious presentation from the 2006 Spring CSER meeting at UVic.
• "Clone detection: How accurate is your data set?" (short paper), Cory J. Kapser and Michael W. Godfrey. Otherwise unpublished, but it's been referenced by others so here it is.
• "Increasing quality of conceptual models: Is object-oriented analysis that simple?", Davor Svetinovic Daniel M. Berry, and Michael W. Godfrey. Proc. of the ICSE 2006 Workshop on The Role of Abstraction in Software Engineering, Shanghai, China, 21 May 2006.
• "Supporting the analysis of clones in software systems: A case study" Cory J. Kapser and Michael W. Godfrey. Journal of Software Maintenance and Evolution, 18(2), March/April 2006.
  • This was a special issue of JSME featuring extended version of invited papers from ICSM-05.

2005

• "Cloning by accident: An empirical study of source code cloning across software systems", Raihan Al-Ekram, Cory J. Kapser, Richard C. Holt, and Michael W. Godfrey. Proc. of the 2005 Intl. Symposium on Empirical Software Engineering (ISESE-05), Noosa Heads, Australia, 17-18 November 2005. [Acceptance rate: 40%]
• "A reference architecture for web browsers", (short paper), Alan Grosskurth and Michael W. Godfrey. Proc. of the 2005 Intl. Conference on Software Maintenance (ICSM-05), Budapest, Hungary, 25-30 Sept 2005. [Acceptance rate: (55+25) / 180 or 44% for short papers.]
  • Also, a preprint of an extended version submitted for journal consideration.
  • Grady Booch sent us email to say that he thought this paper was "wonderful". He has included our architectural model of Mozilla in the architecture gallery of his Handbook of Software Architecture .
• "Improved tool support for the investigation of duplication in software", Cory J. Kapser and Michael W. Godfrey. Proc. of the 2005 Intl. Conference on Software Maintenance (ICSM-05), Budapest, Hungary, 25-30 Sept 2005. [Acceptance rate: 55 / 180 or 30% for full papers]
  • This paper was selected one of the best papers at ICSM-05, and was invited to be extended for consideration in a special issue of the Journal of Software Maintenance and Evolution.
• "Facilitating software evolution research with kenyon", Jennifer Bevan, E. James Whitehead, Jr., Sunghun Kim, and Michael W. Godfrey. Proc. of the 2005 Joint European Software Engineering Conference / ACM SIGSOFT Symposium on the Foundations of Software Engineering (ESEC/FSE-05), Lisbon, Portugal, 5-9 Sept 2005. [Acceptance rate: 32 / 201 or 16%]
• "Concept identification in object-oriented domain analysis: Why some students just don't get it", Davor Svetinovic, Daniel M. Berry, and Michael W. Godfrey. Proc. of 2005 Intl. Conference on Requirements Engineering (RE-05), Paris, France, 31 Aug - 2 Sept 2005. [Acceptance rate: 35 / 175 or 20%] Slides from the presentation: PDF
  • This paper was selected as one of the best papers at RE-05 and was invited to be extended for a journal special issue.
• "Using origin analysis to detect merging and splitting of source code entities", Michael W. Godfrey and Lijie Zou. IEEE Trans, on Software Engineering, 31(2), Feb 2005.
  • An extended version of our WCRE-03 paper; this was a special issue of IEEE-TSE honouring the 10th anniversary of the WCRE conference.
• "Lossy program analysis, or lies my extractor told me", invited presentation at Dagstuhl Seminar No 05161 Transformation Techniques in Software Engineering. PPT version

2004

• "Aiding comprehension of cloning through categorization", Cory J. Kapser and Michael W. Godfrey. Proc. of 2004 Intl. Workshop on Software Evolution (IWPSE-04), Kyoto, Japan, 6-7 September 2004. [Acceptance rate: 8 / 27 or 30%]
• "Four interesting ways in which history can teach us about software", Michael W. Godfrey, Xinyi Dong, Cory J. Kapser, and Lijie Zou. Position paper accepted to and presented at 2004 Intl. Workshop on Mining Software Repositories (MSR-04), Edinburgh, Scotland on 25 May 2004. Slides from the presentation: PDF, PPT.
• "A taxonomy of clones in source code: The re-Engineers most wanted list" (position paper), Cory J. Kapser and Michael W. Godfrey. Proc. of the 2nd Intl. Workshop on Detection of Software Clones (IWDSC-03), Victoria BC, November 2003.

2003

• "A lightweight process for architecture recovery: From code to domain requirements and back again", Davor Svetinovic and Michael W. Godfrey.
• "Detecting merging and splitting using origin analysis", Lijie Zou and Michael W. Godfrey. Proc. of 2003 Working Conference on Reverse Engineering (WCRE-03), Victoria, BC, November 2003. [Acceptance rate: 33 / 72 or 46%] Slides from the presentation: PDF, PPT.
  • This paper was selected as one of the best papers from WCRE-03, and invited to be extended for consideration for the IEEE-TSE special issue honouring the 10th anniversary of the WCRE conference.
• "Toward a taxonomy for source code cloning: A case study", Cory J. Kapser and Michael W. Godfrey. Proc. of the 2003 Intl. Workshop on Evolution of Large-scale Industrial Software Applications (ELISA), Amsterdam, 23 September 2003. This is an extended version; the original can be found in the full ELISA proceedings. Slides from the presentation: PDF, PPT.
• "Architectural (wallpaper) patterns", another not-entirely-serious presentation given at Second ASERC Workshop on Software Architecture, Banff, Alberta, February 2003.
  • There is also a low-res Quicktime movie of the presentation. See and hear the talk that made Rick Kazman of the SEI exclaim, "Mike, don't give up your day job."
• "The build / comprehend pipelines" (position paper), Richard C. Holt, Michael W. Godfrey, and Andrew J. Malton, Second ASERC Workshop on Software Architecture, Banff, Alberta, February 2003.
• "Modelling and extracting the build-time architectural view", Qiang Tu, Michael W. Godfrey, and Xinyi Dong; this is an extended version of the ICSM-01 paper below, submitted for journal consideration.
  • A related talk was given at Dagstuhl Seminar #3061 on Software Architecture: Recovery and Modelling, 2-7 Feb 2003, and also at the University of Koblenz: PDF, PPT
• "Enhancing domain-specific software architecture recovery", Igor Ivkovic and Michael W. Godfrey, Proc. of 2003 Intl. Workshop on Program Comprehension (IWPC-03), Portland, Oregon, May 2003. [Acceptance rate: 27 / 44 or 61%]
  • Grady Booch references this paper in his Handbook of Software Architecture

2002

• "Adoption Centric Networking Environments", a short, not-entirely-serious research proposal, given at the October 2002 CSER meeting.
• "Architectural reconstruction in the dark", (position paper), Andrew Trevors and Michael W. Godfrey. Proc. of the WCRE-02 Workshop on Software Architecture Reconstruction, Richmond VA, November 1, 2002.
• "Semantic grep: Regular expressions + relational abstraction", R. Ian Bull, Andrew Trevors, Andrew J. Malton, and Michael W. Godfrey. Proc. of 2002 Working Conference on Reverse Engineering (WCRE-02), Richmond VA, October 2002. [Acceptance rate: 33 / 72 or 46%]
• "An integrated approach for studying software architectural evolution", Qiang Tu and Michael W. Godfrey, Proc. of 2002 Intl. Workshop on Program Comprehension (IWPC-02), Paris, June 2002. Slides from the presentation: PDF, PPT. [Acceptance rate: 28 / 44 or 64%]
• "Architecture recovery of dynamically linked applications: A case study", Igor Ivkovic and Michael W. Godfrey, Proc. of 2002 Intl. Workshop on Program Comprehension (IWPC-02), Paris, June 2002. [Acceptance rate: 28 / 44 or 64%]
• "Tracking structural evolution using origin analysis" (position paper), Michael W. Godfrey and Qiang Tu, Proc. of 2002 Intl. Workshop on Principles of Software Evolution (IWPSE-02), Orlando, Florida, May 2002.

2001

• Results of the Acacia entry [PPT version] into the "C++ Parser Olympics" that was organized and presented at CASCON 2001 by Susan Sim in Toronto in November 2001. I "drove" the Acacia extractor (aided by Andrew Trevors), which is a product of AT+T Research. There are two plain text files of interest: Introduction to the Acacia System and Results of the running Acacia on the Parser/Analyser Suite .
  • Susan Sim and Holger Kienle ran a second version of this for IWPC 2002; here is the presentation for the Acacia entry: PDF (4up) and PPT.
• "Multi-tired architectures", a not-entirely-serious presentation co-devised by Ric Holt, given at the 2001 ASERC Workshop on Software Architecture in Edmonton, August 24-25, 2001. Also: PDF (4-up) and PPT.
• "How does your software grow?", Michael W. Godfrey. Invited position paper and presentation given at the 2001 ASERC Workshop on Software Architecture in Edmonton, August 24-25, 2001.
• "A lightweight architecture recovery process" (position paper), Davor Svetinovic and Michael W. Godfrey, accepted to SWARM (SoftWare Architecture Recovery and Modelling), a discussion session held in conjunction with WCRE-01, Stuttgart, October 2001.
• "Attribute-based evolution patterns for product lines" (position paper), Davor Svetinovic and Michael W. Godfrey, Proc. of WICSA-01 Workshop on Architecture Reconstruction and Product Lines, Amsterdam, August 2001.
• "Exploring structural change and architectural evolution", a short Powerpoint presentation to the May 2001 meeting of CSER on a tool we (Qiang Tu, really) are working on.
• "Growth, evolution, and structural change in open source software", Michael W. Godfrey and Qiang Tu. Proc. of 2001 Intl. Workshop on Principles of Software Evolution (IWPSE-01), Vienna, September 2001.
  • Grady Booch references this paper in his Handbook of Software Architecture
• "Software engineering research in the bazaar" (position paper), Ahmed E. Hassan, Michael W. Godfrey, and Richard C. Holt. Proc. of 1st ICSE Workshop on Open Source Software Engineering, Toronto, May 2001.
• "Representing build-time software architecture views with UML" (position paper), Qiang Tu and Michael W. Godfrey. Proc. of 2001 ICSE Workshop on Describing Software Architecture with UML, Toronto, May 2001.
• "The build-time software architecture view", Qiang Tu and Michael W. Godfrey. Proc. of 2001 Intl. Conference on Software Maintenance (ICSM-01), Florence, Italy, November 2001. Slides from the presentation: PPT, PDF (6up). [Acceptance rate: 68 / 161 or 42%.] See also the extended version submitted for journal consideration above.

2000

• "Defining, transforming, and exchanging high-level schemas", Michael W. Godfrey, Proc. of 2000 Working Conference on Reverse Engineering (WCRE-00), Brisbane, Australia, November 2000. Slides from the talk in PPT or PDF formats.
• "Evolution, growth, and cloning in Linux: A case study", Michael W. Godfrey, Davor Svetinovic, and Qiang Tu, a presentation at the 2000 CASCON workshop on "Detecting duplicated and near duplicated structures in large software systems: methods and applications", on November 16, 2000, chaired by Ettore Merlo. PPT version. To date, this is the only presentation of the work we have done in examining cloning in the SCSI driver subsystem of Linux.
• "Evolution in open source software: A case study", Michael W. Godfrey and Qiang Tu, Proc. of the 2000 Intl. Conference on Software Maintenance (ICSM-00), San Jose, California, October 2000. Slides from the presentation in PPT and PDF (6up).
  • This is probably my best known work; it got me a mention on salon.com, Süddeutsche Zeitung, First Monday, Cnet's news.com, the Open Source Software Institute, and some other places.
• "High-level schemas: A journey through the bush", a presentation given at ICSE 2000 Workshop on Standard Exchange Format (WoSEF-00). PPT version also available.
• "Practical data exchange for reverse engineering frameworks: Some requirements, some experience, some headaches", Michael W. Godfrey, position paper accepted to ICSE 2000 Workshop on Standard Exchange Format (WoSEF-00). A version of appeared in ACM Software Engineering Notes, vol. 26, no. 1, January 2001. I gave a related talk at the Dagstuhl seminar on Interoperability of Reengineering Tools (Seminar No. 01041, Report No. 296), 21-26 January 2001, and yet another version at the November 1999 CSER meeting: PDF (6 up) and PPT.
• "Toward an understanding of software evolution", a seminar given at the University of Waterloo July 4, 2000 incorporating the results from some of the papers and talks below, especially the case study on the growth of the Linux kernel detailed in "Evolution in Open Source Software: A Case Study". The PPT version is also available.
• "Secrets from the monster: Extracting Mozilla's software architecture", Michael W. Godfrey and Eric H. S. Lee, Proc. of the Second Intl. Symposium on Constructing Software Engineering Tools (CoSET-00), Limerick, Ireland, June 2000. Slides from the presentation: PDF (6up) and PPT .
• "Architecture repair of open source software", John B. Tran, Michael W. Godfrey, Eric H. S. Lee, and Richard C. Holt, Proc. of 2000 Intl. Workshop on Program Comprehension (IWPC-00), Limerick, Ireland, June 2000.

1999 and earlier

• "Extracting source models from Java programs: Parse, disassemble, or profile?", Ivan Bowman, Michael W. Godfrey, and Ric Holt. Otherwise unpublished, but it's been cited a few times by people I don't know, so here it is.
• "Visualizing architectural evolution", James P. D. Keast, Mark G. Adams, and Michael W. Godfrey, Proc. of ICSE-99 Workshop on Software Change and Evolution (SCE-99), Los Angeles, May 1999.
• "Connecting architecture reconstruction frameworks" (preprint), Ivan Bowman, Michael W. Godfrey, and Ric Holt, Proc. of the First Intl. Symposium on Constructing Software Engineering Tools (CoSET-99), Los Angeles, May 1999. Also published in Journal of Information and Software Technology, 42(2), pp. 93-104, February 2000. Slides from the presentation: PDF (6up) and PPT .
• "JDuck: Building a software engineering tool in Java as a CS2 project" (preprint), Michael W. Godfrey and Dan Grossman, Proc. of SIGCSE -99, March 1999.
  • This is one of my favourite pieces of work (and presenting at SIGCSE in New Orleans was fun too). I have a detailed web page on this project, plus slides from the talk.
• "Secure and portable database extensibility", Michael W. Godfrey, Tobias Mayr, Praveen Seshadri, and Thorsten von Eicken, Proc. of SIGMOD-98, Seattle WA, June 1998. [Acceptance rate: 42 / 246 or 17%]
• "Teaching software engineering to a mixed audience" (preprint), Michael W. Godfrey, Journal of Information and Software Technology, 40(4), pp. 229-232, July 1998.
• "Prototyping a visual formalism for system modelling", Michael W. Godfrey, Richard C. Holt and Spiros Mancoridis, Proc. of the ICSE-16 Workshop on Software Engineering and Human-Computer Interaction , Sorrento, Italy, May 1994, published as Lecture Notes in Computer Science vol. 896, Springer Verlag, February 1995.
• "Tool support for software engineering education", Spiros Mancoridis, Richard C. Holt and Michael W. Godfrey, Proc. of the ICSE-16 Workshop on Software Engineering Education, Sorrento, Italy, published as Imperial College Dept. of Computing Technical Report 94/6, June 1994.
• "A program understanding environment based on the Star approach to tool integration", Spiros Mancoridis, Richard C. Holt and Michael W. Godfrey, Proc. of 22nd Annual ACM Computer Science Conference (CSC-94), Phoenix, USA, March 8-10, 1994.
• "Visual formalisms for configuration management", Michael W. Godfrey, Proc. of CASCON-93, October 1993.
• "Formal specification in metamorphic programming", David A. Penny, Richard C. Holt and Michael W. Godfrey, Proc. of the 4th Intl. Symposium of VDM Europe , Springer-Verlag Lecture Notes in Computer Science no. 551, October 1991.
• "Spectur -- A specification language for the programmer", Michael W. Godfrey and Richard C. Holt, Technical Report CSRI-241, University of Toronto, June 1990.