6th International Workshop on

Preferences and Soft Constraints

Held in conjunction with

10th International Conference on
Principles and Practice of Constraint Programming, CP2004

September 27 - October 1, 2004
Toronto, Canada


Overview ]

Scope ]

Submissions ]

Important Dates ]

Accepted Papers ]

Schedule ]

Organisation ]


Preferences are ubiquitous in real life: most problems are over-constrained and would not be solvable if we insist that all their requirements are strictly met. Moreover, many problems are more naturally described via preference rather than hard statements. Soft constraints are the way the constraint community has extended his classical framework to deal with the conceept of preferences. However, other frameworks for expressing preferences have been proposed in the last few years in AI or related disciplines, with different features and leading to different results. For example, both qualitative and quantitative preference frameworks are being studied and used to model and solve real-life probleems.

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This workshop would like to bring together researchers interested in all aspects of preferences and soft constraints, such as:

  • theoretical frameworks
  • problem modeling
  • solving algorithms
  • languages
  • preference aggregation
  • preference elicitation
  • multi-objective or qualitative optimization
  • combining/integrating different frameworks and algorithms
  • comparative studies
  • real-life applications

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This workshop is intended to build on the experience and success of the workshops on soft constraints that have been held at CP99, CP2000, CP2001, CP2002 and CP2003, and on the AAAI 2002 workshop on preferences in AI and CP. Its aim is to provide a forum where researchers currently working in the area of preferences or soft constraints can discuss their most recent ideas and developments and think together about the most promising new directions.
Therefore we encourage the presentation of work in progress or on specialized aspects of soft constraints. Papers that bridge the gap between theory and practice are especially welcome.

Prospective attendees can submit a paper, which can be up to 15 pages in length.
We encourage authors to submit papers electronically in postscript or pdf format. Papers should be formatted using the Lecture Notes in Computer Science (LNCS) style.
Please send your submissions by email to using the subject line Soft-2004 Workshop Submission.

Although no agreement is yet in place, we will consider the publication of a selection of papers presented at this workshop in a special issue of a journal or in a volume of a serie.

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Important Dates

The proposed schedule of important dates for the workshop is as follows:

Paper Submission deadline June 26th
Notification of acceptance July 24th
Camera-ready version deadline August 14th
Workshop Date September 27th

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Accepted papers

Workshop Schedule

  Opening Remarks
S. Bistarelli, F. Rossi
09:00 On Global Warming (Softening Global Constraints)
Willem Jan van Hoeve, Gilles Pesant, Luois-Martin Rousseau
09:30 On-demand Bound Computation for Finding Leading Solutions to Soft Constraints
Martin Sachenbacher, Brian C. Williams
10:00 Implementing Semiring-based Constraints using a Concurrent Constraint Programming Language
Alberto Delgado, Carlos Alberto Olarte, Jorge Andre's Pe'rez
Coffee Break (10:30-11:00)
11:00 Constrained CP nets
Steve Prestwich, Francesca Rossi, K. Brent Venable, Toby Walsh
11:30 Learning Calendar Scheduling Preferences in Hierarchical Organizations
Jean Oh, Stephen Smith
12:00 Reasoning about fuzzy preferences and uncertainty
Maria Silvia Pini, Francesca Rossi, K. Brent Venable
Lunch (12:30-14:00)
14:00 Decision Diagrams for the Computation of Semiring Valuations
Nic Wilson
14:30 AND/OR Tree Search for Constraint Optimization
Radu Marinescu, Rina Dechter
15:00 Bucket elimination with capacity constraints
Javier Larrosa, Emma Rollo'n
Coffee Break (15:30-16:00)
16:00 Singleton Consistency and Dominance testing for weighted CSP
Simon de Givry
16:30 Towards robust DAC-based solvers for WCSP
Federico Heras, Javier Larrosa
17:00 An exact Max-SAT Solver for over-constrained Problems
Josep Argelich, Felip Manya'
  Concluding Remarks
S. Bistarelli, F. Rossi

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Organising Committee

Stefano Bistarelli (Primary Contact)
Dipartimento di Scienze
Università degli studi "G. D'Annunzio" di Chieti-Pescara, Italy
Istituto di Informatica e Telematica
C.N.R. Pisa, Italy

Francesca Rossi
Dipartimento di Matematica Pura ed Applicata
Universita' degli Studi di Padova, Italy

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Programme Committee

Stefano Bistarelli (University of Pescara, Italy --- C.N.R., Pisa, Italy)
Simon De Givry (Institut National de La Recherche Agronomique, Castanet Tolosan Cedex, France)
Boi Faltings (EPFL, Switzerland)
Carmen Gervet (IC-Parc, Imperial College, UK)
Ulrich Junker (ILOG, France)
Javier Larrosa (Universitat Politècnica de Catalunya, UPC, Barcelona, Spain)
Jimmy H. M. Lee (The Chinese University of Hong Kong, Hong Kong)
Pedro Meseguer (IIIA-CSIC, Bellaterra, Spain)
Barry O'Sullivan (University College Cork, Ireland)
Francesca Rossi (University of Padova, Italy)
Thomas Schiex (Institut National de La Recherche Agronomique, Castanet Tolosan Cedex, France)
Toby Walsh (Cork Constraints Computation Centre, Ireland)

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