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Variable and value elimination in binary constraint satisfaction via forbidden patterns

Authors: 

David Cohen, Martin Cooper, Guillaume Escamocher, Standa Zivny

Publication Type: 
Refereed Original Article
Abstract: 
Variable or value elimination in a constraint satisfaction problem (CSP) can be used in preprocessing or during search to reduce search space size. A variable elimination rule (value elimination rule) allows the polynomial-time identification of certain variables (domain elements) whose elimination, without the introduction of extra compensatory constraints, does not affect the satisfiability of an instance. We show that there are essentially just four variable elimination rules and three value elimination rules defined by forbidding generic sub-instances, known as irreducible existential patterns, in arc-consistent CSP instances. One of the variable elimination rules is the already-known Broken Triangle Property, whereas the other three are novel. The three value elimination rules can all be seen as strict generalisations of neighbourhood substitution.
Digital Object Identifer (DOI): 
10.1016/j.jcss.2015.02.001
Publication Status: 
Published
Date Accepted for Publication: 
Friday, 23 January, 2015
Publication Date: 
30/11/2015
Journal: 
Journal of Computer and System Sciences
Volume: 
81
Issue: 
7
Pages: 
1127-1143
Institution: 
National University of Ireland, Cork (UCC)
Open access repository: 
Yes
Publication document: