ModRef 2020

The 19th workshop on Constraint Modelling and Reformulation

September 7th, 2021; Louvain-la-Neuve, Belgium

ModRef 2020 is the 19th in a series of workshops on Constraint Modelling and Reformulation. ModRef has always been co-located with the Constraint Programming (CP) conference in the past. The workshop will run at The 26th International Conference on Principles and Practice of Constraint Programming, CP2020 in Louvain-la-Neuve, Belgium on September 7th 2020.

Recent years have witnessed significant research devoted to modelling and solving problems with constraints. The importance of modelling and model reformulation is widely recognised. There have been developments in systematic and automated ways of improving aspects of modelling and model reformulation. Tools and techniques which provide the ability to target multiple kinds of solvers were also developed.

The key goals of this workshop are to extend the understanding of constraint modelling and to automate aspects of modelling or model reformulation to extend the reach of constraint solvers on difficult problems and ease the task of modelling. We solicit original papers that contribute to either or both of these goals.

Workshop topics include:

Call for Presentations

This year ModRef will again include presentations that are not based on submitted papers. In addition to the presentation of research results, we especially welcome talks describing ongoing work, recent breakthroughs, future directions, and descriptions of interesting aspects of existing systems. Lightweight submissions must be in the form of a one (1) or two (2) pages extended abstract (excluding references) in the Lecture Notes in Computer Science (LNCS) style. Please submit your extended abstract in PDF format using EasyChair.

Call for Papers

In addition to the short form abstract only submissions we are also accepting full paper submissions. These must be formatted in the Lecture Notes in Computer Science (LNCS) style and must be within 15 pages excluding references. Submissions of shorter papers, including position papers, are also welcome. Please submit your paper in PDF format using EasyChair.

All submissions will be reviewed and those that are well-written and make a worthwhile contribution to the topic of the workshop will be accepted for publication in the workshop proceedings. The proceedings will be available electronically at CP 2020. Accepted contributions will be allowed a time slot for a presentation at the workshop. At least one author of each accepted paper must attend and present at the workshop. Please note that every workshop participant needs to be registered for the workshop.

Please feel free to get in touch (jea20[at_symbol] or nttd[at_symbol] to express interest, to have an informal discussion, etc.

Important Dates

Abstract submission July 23rd, 2020
Final submission (extended abstract/full paper) July 29th, 2020
Notification of acceptance/rejection August 7th, 2020
Camera ready version August 24th, 2020
Workshop day September 7th, 2020

Program Committee

Joan Espasa Arxer (Chair) University of St. Andrews
Nguyen Dang (Chair) University of St. Andrews
Kevin Leo Monash University
Alan Frisch University of York
Mateu Villaret Universitat de Girona
Peter Nightingale University of York
Christopher Jefferson University of St. Andrews
Michael Morin Université Laval
Zeynep Kiziltan University of Bologna
María Andreína Francisco Rodríguez Uppsala University
Jordi Coll Universitat de Girona
Ciaran McCreesh University of Glasgow
Özgür Akgün University of St. Andrews
Ken Brown University College Cork
Emir Demirović Delft University of Technology
Jimmy Ho Man Lee The Chinese University of Hong Kong

Program (September 7th, 2020)

To attend the workshop, you can register for CP2020 (free) and access the Workshop session via CP’s Online platform.

Time (CEST) Authors Title
13:00 Invited talk: Maria Garcia de la Banda Rethinking Model Reformulation: from Speed focused to Human focused (video)
13:45 Mateusz Ślażyński, Salvador Abreu and Grzegorz J. Nalepa Specifying Local Search Neighborhoods from a Constraint Satisfaction Problem Structure (paper) (video)
14:00 Mikael Z. Lagerkvist and Magnus Rattfeldt Half-checking propagators (paper) (video) (slides)
14:15 Gökberk Koçak, Özgür Akgün, Nguyen Dang and Ian Miguel Efficient Incremental Modelling and Solving (paper) (video)
14:30 Break  
15:00 Vitaly Lagoon and Amit Metodi Deriving Optimal Multiplication-by-Constant Circuits With A SAT-based Constraint Engine (paper) (video)
15:15 Federico Toffano, Nic Wilson and Paolo Viappiani Efficient Exact Computation of Setwise Minimax Regret (paper) (video)
15:30 Özgür Akgün, Nguyen Dang, Joan Espasa, Ian Miguel, András Salamon and Christopher Stone Exploring Instance Generation for Automated Planning (paper) (video) (slides)
15:45 Break  
16:15 Invited talk: Tias Guns Hybrid Prediction and Constraint Solving (video)
17:00 Maria Andreina Francisco Rodriguez and Ola Spjuth A Constraint Programming Approach to Microplate Layout Design (paper) (video) (slides)
17:15 Helmut Simonis, Simon de Givry, Thomas Schiex and Andreas Schutt Modelling the Conference Paper Assignment Problem (paper) (video)
17:30 Patrick Spracklen, Nguyen Dang, Özgür Akgün and Ian Miguel Towards Portfolios of Streamlined Constraint Models: A Case Study with the Balanced Academic Curriculum Problem (paper) (video)
17:45 End of workshop  

Invited Talks

This year we are honored to host the two following invited talks:

Maria Garcia de la Banda - Rethinking Model Reformulation: from Speed focused to Human focused

Maria Garcia de la Banda is a Professor at the Faculty of Information Technology, at Monash University and has more than 25 years of experience as an academic. Prof. Garcia de la Banda’s PhD won the Universidad Politécnica de Madrid’s Best PhD Award. She was awarded the first and only prestigious Logan Fellowship, a role she held for 6 years. She has been an elected member of the Executive Committee of the Association of Logic Programming, and of the Association for Constraint Programming, of which she is currently president.

Prof. Garcia de la Banda has extensive research experience in the modelling and solving of combinatorial problems, with particular emphasis on the (semi-)automatic analysis and transformation of constraint programming models. In 2005 she jointly won the International Constraint Modelling Challenge. During her career she has kept her feet on the ground, being involved in transferring her expertise to a long list of real-world applications.

Tias Guns - Hybrid Prediction and Constraint Solving

Tias Guns is Assistant Professor at the Vrije Universiteit Brussel (VUB), in the Business, Technology and Operations lab of the faculty of Economic and Social Sciences & Solvay Business School. His research lies on the border between data mining and constraint programming, and his main interest is in integrating domain expertise and user constraints into data analytics tasks. As part of his PhD, he has developed the CP4IM framework which showed for the first time the potential of using constraint programming for pattern mining. His PhD was awarded with both the constraint programming dissertation award and the ECCAI artificial intelligence dissertation award. He is an active member of the community and has organized a number of workshops and a special issue on the topic of combining constraint programming with machine learning and data mining.

Abstract: Increasingly, the knowledge needed to formulate constraint solving problems is not explicitly written down. Instead, we have to infer part of the knowledge implicitely from the users, (such as preferences), or through perception (image recognition) or the environment (price predictions). In this task I motivate this change in requirements and the challenges it poses with respect to modeling and (re)formulating such data-driven constraint solving problems.

Previous ModRef Workshops

The ModRef workshop has been running for 19 years and has hosted many interesting presentations.