Computing Explanations for the Unary Resource Constraint

Integration of explanations into a CSP solver is a technique addressing difficult question “why my problem has no solution”. Moreover, explanations together with advanced search methods like directed backjumping or dynamic backtracking can be used to effectively cut off parts of the search tree and this way speed up the search. In order to use explanations, propagation algorithms must provide some sort of reasons (justifications) for their actions. For binary constraints it is mostly easy. However in the case of global constraints, computation of factual justifications can be tricky, especially when no considerable slowdown of the propagation algorithm is affordable. This papers shows how to compute justifications for the unary resource constraint and how to use these justifications to create explanations. The asset of the explanations is experimentally demonstrated on jobshop benchmark problems. The following propagation algorithms for the unary resource constraint are cons...

• Type: Conference
• Year: 2005
• Where: CPAIOR
• Authors: Petr Vilím
• Keywords: CPAIOR 2005, Propagation Algorithms, Technique Addressing Difficult, Unary Resource Constraint