A cost-regular based hybrid column generation approach

Constraint Programming (CP) offers a rich modeling language of constraints embedding efficient algorithms to handle complex and heterogeneous combinatorial problems. To solve hard combinatorial optimization problems using CP alone or hybrid CP-ILP decomposition methods, costs also have to be taken i...

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Bibliographic Details
Published in:	Constraints (Dordrecht) 2006-12, Vol.11 (4), p.315-333
Main Authors:	DEMASSEY, Sophie, PESANT, Gilles, ROUSSEAU, Louis-Martin
Format:	Article
Language:	eng
Subjects:	Applied sciences Artificial Intelligence Computer Science Exact sciences and technology Flows in networks. Combinatorial problems Operational research and scientific management Operational research. Management science Operations Research
Online Access:	Get full text
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Summary:	Constraint Programming (CP) offers a rich modeling language of constraints embedding efficient algorithms to handle complex and heterogeneous combinatorial problems. To solve hard combinatorial optimization problems using CP alone or hybrid CP-ILP decomposition methods, costs also have to be taken into account within the propagation process. Optimization constraints, with their cost-based filtering algorithms, aim to apply inference based on optimality rather than feasibility. This paper introduces a new optimization constraint: cost-regular. Its filtering algorithm is based on the computation of shortest and longest paths in a layered directed graph. The support information is also used to guide the search for solutions. We believe this constraint to be particularly useful in modeling and solving Column Generation subproblems and evaluate its behaviour on complex Employee Timetabling Problems through a flexible CP-based column generation approach. Computational results on generated benchmark sets and on a complex real-world instance are given.
ISSN:	1383-7133 1572-9354