Dr William Pettersson
- Research Software Engineer (School of Computing Science)
telephone:
0141 330 5456
email:
William.Pettersson@glasgow.ac.uk
Room F132, Lilybank Gardens
https://orcid.org/0000-0003-0040-2088Biography
I am a Research Associate at the School of Computing Science, University of Glasgow. I am working on the IP-MATCH EPSRC project, under the supervision of Dr David Manlove. The goal of such research is to allow the best possible allocation of resources. For instance, one outcome of the project is an allocation of kidney donors to patients, or the allocation of student doctors to hospitals.
Prior to coming to Glasgow, I have lived in various cities in Australia working on parallel exact integer multi-objective optimisation algorithms. I am also an accomplished graph theorist and topologist, specialising in algorithms in graph decompositions and combinatorial topology respectively.
Research interests
Very broadly, I am interested in solving problems with computers. This includes both complexity theory, the theoretical efficiency of an algorithm, as well as the practical running-time efficiency of an algorithm or approach.
Currently I am using integer programming to solve large and complex matching problems under the guidance of Dr David Manlove, and funded by EPSRC grant IP-MATCH. The goal of such research is to allow the best possible allocation of resources. For instance, one outcome of the project is an allocation of kidney donors to patients, or the allocation of student doctors to hospitals.
I have also spent significant time working on a software package called Regina. Regina is a mathematical software suite for combinatorial topologists. This work includes new algorithms, implementation of existing algorithms, and also various user-interface and user-experience updates.
My pet research projects are finding graph decompositions, often through computing. In this, I have researched various theoretical IP and LP techniques (such as constraint generation, Bender's decompositions) as well as more practical issues such as parallelisation techniques and even micro-optimisations in software. My big breakthrough in this area was the completion of the cycle decomposition problem, and I am currently, albeit slowly, working away on the Oberwolfach problem.
To aid various search engines, I here include some key research words and topics that interest me:
- Parameterised complexity and fixed-parameter tractability
- Graph algorithms, in particular colourings and decompositions
- Exact multi-objective integer programming
- Parallel algorithms
- Graph decompositions
- High performance computing
Publications
2024
Enright, J. , Larios-Jones, L., Meeks, K. and Pettersson, W. (2024) Reachability in Temporal Graphs under Perturbation. In: 50th International Conference on Current Trends in Theory and Practice of Computer Science (SOFSEM 2025), Bratislava, Slovakia, 20-23 Jan 2025, (Accepted for Publication)
Ashlagi, I., Cseh, Á., Manlove, D. , Ockenfels, A. and Pettersson, W. (2024) Designing a kidney exchange program in Germany: simulations and recommendations. Central European Journal of Operations Research, (doi: 10.1007/s10100-024-00933-0) (Early Online Publication)
Enright, J. , Lee, D. , Meeks, K. , Sylvester, J. and Pettersson, W. (2024) The complexity of finding and enumerating optimal subgraphs to represent spatial correlation. Algorithmica, (doi: 10.1007/s00453-024-01256-x) (Early Online Publication)
Delorme, M., García, S., Gondzio, J., Kalcsics, J., Manlove, D. and Pettersson, W. (2024) New algorithms for hierarchical optimization in kidney exchange programs. Operations Research, 72(4), pp. 1654-1673. (doi: 10.1287/opre.2022.2374)
2023
Pettersson, W. and Sylvester, J. (2023) Bounds on the twin-width of product graphs. Discrete Mathematics and Theoretical Computer Science, 25(1), 18. (doi: 10.46298/dmtcs.10091)
Enright, J. , Meeks, K. , Pettersson, W. and Sylvester, J. (2023) Cops and robbers on multi-layer graphs. In: Graph-Theoretic Concepts in Computer Science:49th International Workshop, WG 2023, Fribourg, Switzerland, June 28–30, 2023, Revised Selected Papers. Series: Lecture notes in computer science (14093). Springer: Cham. ISBN 9783031433795 (Accepted for Publication)
2022
Pettersson, W. (2022) kep_solver: a Python package for kidney exchange programme exploration. Journal of Open Source Software, 7(80), 4881. (doi: 10.21105/joss.04881)
Delorme, M., García, S., Gondzio, J., Kalcsics, J., Manlove, D. , Pettersson, W. and Trimble, J. (2022) Improved instance generation for kidney exchange programmes. Computers and Operations Research, 141, 105707. (doi: 10.1016/j.cor.2022.105707)
2021
Delorme, M., García, S., Gondzio, J., Kalcsics, J., Manlove, D. and Pettersson, W. (2021) Stability in the hospitals/residents problem with couples and ties: mathematical models and computational studies. Omega, 103, 102386. (doi: 10.1016/j.omega.2020.102386)
Lee, D. , Meeks, K. and Pettersson, W. (2021) Improved inference for areal unit count data using graph-based optimisation. Statistics and Computing, 31(4), 51. (doi: 10.1007/s11222-021-10025-7)
Biró, P. et al. (2021) Modelling and optimisation in European kidney exchange programmes. European Journal of Operational Research, 291(2), pp. 447-456. (doi: 10.1016/j.ejor.2019.09.006)
Pettersson, W. , Delorme, M., García, S., Gondzio, J., Kalcsics, J. and Manlove, D. (2021) Improving solution times of stable matching problems through preprocessing. Computers and Operations Research, 128, 105128. (doi: 10.1016/j.cor.2020.105128)
Smeulders, B. et al. (2021) Data and optimization requirements for Kidney Exchange Programs. Health Informatics Journal, 27(2), pp. 1-15. (doi: 10.1177/14604582211009918) (PMID:33878984)
Enright, J. , Lee, D. , Meeks, K. , Pettersson, W. and Sylvester, J. (2021) The complexity of finding optimal subgraphs to represent spatial correlation. In: Du, Ding-Zhu, Du, Donglei, Wu, Chenchen and Xu, Dachuan (eds.) Combinatorial Optimization and Applications. Series: Lecture Notes in Computer Science (13135). Springer, pp. 152-166. ISBN 9783030926809 (doi: 10.1007/978-3-030-92681-6_13)
2020
Pettersson, W. and Ozlen, M. (2020) Multi-objective integer programming: synergistic parallel approaches. INFORMS Journal on Computing, 32(2), pp. 461-472. (doi: 10.1287/ijoc.2018.0875)
2019
Delorme, M., Garcia, S., Gondzio, J., Kalcsics, J., Manlove, D. and Pettersson, W. (2019) Mathematical models for stable matching problems with ties and incomplete lists. European Journal of Operational Research, 277(2), pp. 426-441. (doi: 10.1016/j.ejor.2019.03.017)
McCreesh, C. , Pettersson, W. and Prosser, P. (2019) Understanding the empirical hardness of random optimisation problems. In: 25th International Conference on Principles and Practice of Constraint Programming, Stamford, CT, USA, 30 Sep - 04 Oct 2019, pp. 333-349. (doi: 10.1007/978-3-030-30048-7_20)
2017
Pettersson, W. and Ozlen, M. (2017) A parallel approach to bi-objective integer programming. ANZIAM Journal, 58, C69-C81. (doi: 10.21914/anziamj.v58i0.11724)
Burton, B., Cabello, S., Kratsch, S. and Pettersson, W. (2017) The Parameterized Complexity of Finding a 2-Sphere in a Simplicial Complex. In: 34th Symposium on Theoretical Aspects of Computer Science (STACS 2017), Hannover, Germany, 8-11 March 2017, 18:1-18:14. ISBN 9783959770286 (doi: 10.4230/LIPIcs.STACS.2017.18)
2015
Bryant, D., Danziger, P. and Pettersson, W. (2015) Bipartite 2-ractorizations of complete multipartite graphs. Journal of Graph Theory, 78(4), pp. 287-294. (doi: 10.1002/jgt.21806)
Burton, B. A. and Pettersson, W. (2015) An Edge-Based Framework for Enumerating 3-Manifold Triangulations. In: 31st International Symposium on Computational Geometry (SoCG 2015), Eindhoven, The Netherlands, 22-25 June 2015, pp. 270-284. ISBN 9783939897835 (doi: 10.4230/LIPIcs.SOCG.2015.270)
2014
Bryant, D., Horsley, D. and Pettersson, W. (2014) Cycle decompositions V: Complete graphs into cycles of arbitrary lengths. Proceedings of the London Mathematical Society, 108(5), pp. 1153-1192. (doi: 10.1112/plms/pdt051)
Burton, B. A. and Pettersson, W. (2014) Fixed Parameter Tractable Algorithms in Combinatorial Topology. In: International Computing and Combinatorics Conference (COCOON 2014), Atlanta, GA, USA, 4-6 Aug 2014, pp. 300-311. ISBN 9783319087825 (doi: 10.1007/978-3-319-08783-2_26)
Articles
Ashlagi, I., Cseh, Á., Manlove, D. , Ockenfels, A. and Pettersson, W. (2024) Designing a kidney exchange program in Germany: simulations and recommendations. Central European Journal of Operations Research, (doi: 10.1007/s10100-024-00933-0) (Early Online Publication)
Enright, J. , Lee, D. , Meeks, K. , Sylvester, J. and Pettersson, W. (2024) The complexity of finding and enumerating optimal subgraphs to represent spatial correlation. Algorithmica, (doi: 10.1007/s00453-024-01256-x) (Early Online Publication)
Delorme, M., García, S., Gondzio, J., Kalcsics, J., Manlove, D. and Pettersson, W. (2024) New algorithms for hierarchical optimization in kidney exchange programs. Operations Research, 72(4), pp. 1654-1673. (doi: 10.1287/opre.2022.2374)
Pettersson, W. and Sylvester, J. (2023) Bounds on the twin-width of product graphs. Discrete Mathematics and Theoretical Computer Science, 25(1), 18. (doi: 10.46298/dmtcs.10091)
Pettersson, W. (2022) kep_solver: a Python package for kidney exchange programme exploration. Journal of Open Source Software, 7(80), 4881. (doi: 10.21105/joss.04881)
Delorme, M., García, S., Gondzio, J., Kalcsics, J., Manlove, D. , Pettersson, W. and Trimble, J. (2022) Improved instance generation for kidney exchange programmes. Computers and Operations Research, 141, 105707. (doi: 10.1016/j.cor.2022.105707)
Delorme, M., García, S., Gondzio, J., Kalcsics, J., Manlove, D. and Pettersson, W. (2021) Stability in the hospitals/residents problem with couples and ties: mathematical models and computational studies. Omega, 103, 102386. (doi: 10.1016/j.omega.2020.102386)
Lee, D. , Meeks, K. and Pettersson, W. (2021) Improved inference for areal unit count data using graph-based optimisation. Statistics and Computing, 31(4), 51. (doi: 10.1007/s11222-021-10025-7)
Biró, P. et al. (2021) Modelling and optimisation in European kidney exchange programmes. European Journal of Operational Research, 291(2), pp. 447-456. (doi: 10.1016/j.ejor.2019.09.006)
Pettersson, W. , Delorme, M., García, S., Gondzio, J., Kalcsics, J. and Manlove, D. (2021) Improving solution times of stable matching problems through preprocessing. Computers and Operations Research, 128, 105128. (doi: 10.1016/j.cor.2020.105128)
Smeulders, B. et al. (2021) Data and optimization requirements for Kidney Exchange Programs. Health Informatics Journal, 27(2), pp. 1-15. (doi: 10.1177/14604582211009918) (PMID:33878984)
Pettersson, W. and Ozlen, M. (2020) Multi-objective integer programming: synergistic parallel approaches. INFORMS Journal on Computing, 32(2), pp. 461-472. (doi: 10.1287/ijoc.2018.0875)
Delorme, M., Garcia, S., Gondzio, J., Kalcsics, J., Manlove, D. and Pettersson, W. (2019) Mathematical models for stable matching problems with ties and incomplete lists. European Journal of Operational Research, 277(2), pp. 426-441. (doi: 10.1016/j.ejor.2019.03.017)
Pettersson, W. and Ozlen, M. (2017) A parallel approach to bi-objective integer programming. ANZIAM Journal, 58, C69-C81. (doi: 10.21914/anziamj.v58i0.11724)
Bryant, D., Danziger, P. and Pettersson, W. (2015) Bipartite 2-ractorizations of complete multipartite graphs. Journal of Graph Theory, 78(4), pp. 287-294. (doi: 10.1002/jgt.21806)
Bryant, D., Horsley, D. and Pettersson, W. (2014) Cycle decompositions V: Complete graphs into cycles of arbitrary lengths. Proceedings of the London Mathematical Society, 108(5), pp. 1153-1192. (doi: 10.1112/plms/pdt051)
Book Sections
Enright, J. , Meeks, K. , Pettersson, W. and Sylvester, J. (2023) Cops and robbers on multi-layer graphs. In: Graph-Theoretic Concepts in Computer Science:49th International Workshop, WG 2023, Fribourg, Switzerland, June 28–30, 2023, Revised Selected Papers. Series: Lecture notes in computer science (14093). Springer: Cham. ISBN 9783031433795 (Accepted for Publication)
Enright, J. , Lee, D. , Meeks, K. , Pettersson, W. and Sylvester, J. (2021) The complexity of finding optimal subgraphs to represent spatial correlation. In: Du, Ding-Zhu, Du, Donglei, Wu, Chenchen and Xu, Dachuan (eds.) Combinatorial Optimization and Applications. Series: Lecture Notes in Computer Science (13135). Springer, pp. 152-166. ISBN 9783030926809 (doi: 10.1007/978-3-030-92681-6_13)
Conference Proceedings
Enright, J. , Larios-Jones, L., Meeks, K. and Pettersson, W. (2024) Reachability in Temporal Graphs under Perturbation. In: 50th International Conference on Current Trends in Theory and Practice of Computer Science (SOFSEM 2025), Bratislava, Slovakia, 20-23 Jan 2025, (Accepted for Publication)
McCreesh, C. , Pettersson, W. and Prosser, P. (2019) Understanding the empirical hardness of random optimisation problems. In: 25th International Conference on Principles and Practice of Constraint Programming, Stamford, CT, USA, 30 Sep - 04 Oct 2019, pp. 333-349. (doi: 10.1007/978-3-030-30048-7_20)
Burton, B., Cabello, S., Kratsch, S. and Pettersson, W. (2017) The Parameterized Complexity of Finding a 2-Sphere in a Simplicial Complex. In: 34th Symposium on Theoretical Aspects of Computer Science (STACS 2017), Hannover, Germany, 8-11 March 2017, 18:1-18:14. ISBN 9783959770286 (doi: 10.4230/LIPIcs.STACS.2017.18)
Burton, B. A. and Pettersson, W. (2015) An Edge-Based Framework for Enumerating 3-Manifold Triangulations. In: 31st International Symposium on Computational Geometry (SoCG 2015), Eindhoven, The Netherlands, 22-25 June 2015, pp. 270-284. ISBN 9783939897835 (doi: 10.4230/LIPIcs.SOCG.2015.270)
Burton, B. A. and Pettersson, W. (2014) Fixed Parameter Tractable Algorithms in Combinatorial Topology. In: International Computing and Combinatorics Conference (COCOON 2014), Atlanta, GA, USA, 4-6 Aug 2014, pp. 300-311. ISBN 9783319087825 (doi: 10.1007/978-3-319-08783-2_26)
Research datasets
2024
Pettersson, W. (2024) Designing a Kidney Exchange Program in Germany: Simulations and Recommendations. [Data Collection]
2021
Delorme, M., Garcia, S., Gondzio, J., Kalcsics, J., Manlove, D. , Pettersson, W. and Trimble, J. (2021) Improved instance generation for kidney exchange programmes. [Data Collection]
Delorme, M., García, S., Gondzio, J., Kalcsics, J., Manlove, D. , Pettersson, W. and Trimble, J. (2021) A new matheuristic and improved instance generation for kidney exchange programmes. [Data Collection]
2020
Pettersson, W. , Delorme, M., García, S., Gondzio, J., Kalcsics, J. and Manlove, D. (2020) Enhanced mathematical models for hierarchical optimisation in kidney exchange programmes. [Data Collection]
Pettersson, W. , Delorme, M., García, S., Gondzio, J., Kalcsics, J. and Manlove, D. (2020) Stability definitions for the Hospitals / Residents problem with Couples and Ties: Mathematical models and computational studies. [Data Collection]
2019
Pettersson, W. , Delorme, M., García, S., Gondzio, J., Kalcsics, J. and Manlove, D. (2019) Improving solution times of stable matching problems through preprocessing. [Data Collection]
2018
Pettersson, W. (2018) Multi-objective integer programming: Synergistic parallel approaches. [Data Collection]
Delorme, M., García, S., Gondzio, J., Kalcsics, J., Pettersson, W. and Manlove, D. (2018) Mathematical models for stable matching problems with ties and incomplete lists. [Data Collection]
Additional information
I have previously worked on parallel algorithms for exact multi-objective integer optimisation with A.Prof Melih Ozlen. In this work, I implemented the following parallel algorithms
moip_aira - An implementation of EPP, SPREAD and CLUSTER, as detailed in <forthcoming>
boxfinder - An implementation of the algorithm from Kerstin Dächert, Kathrin Klamroth (2015). A linear bound on the number of scalarizations needed to solve discrete tricriteria optimization problems. Journal of Global Optimization, 61(4), 643--676
kppm - An implementation of the algorithm from C. Dhaenens, , J. Lemesre, E.G. Talbi (2008). K-PPM: A new exact method to solve multi-objective combinatorial optimization problems. European Journal of Operational Research, 200(1), 45-53.
I am also a developer of Regina, a suite of mathematical software for combinatorial topologists.
