Opportunistic Specialization in Russian Doll Search
Russian Doll Search (RDS) is a clever procedure to solve overconstrained problems. RDS solves a sequence of nested subproblems, each including one more variable than the previous, until the whole problem is solved. Specialized RDS (SRDS) solves each subproblem for every value of the new variable. SRDS lower bound is better than RDS lower bound, causing a higher efficiency. A natural extension is Full Specialized RDS (FSRDS), which solves each subproblem for every value of every variable. Although FSRDS lower bound is better than the SRDS one, the extra work performed by FSRDS renders it inefficient. However, much of the useless work can be avoided. With this aim, we present Opportunistic Specialization in RDS (OSRDS), an algorithm that lies between SRDS and FSRDS. In addition to specialize the values of one variable, OSRDS specializes some values of other variables that look promising to increase the lower bound in the current distribution of inconsistency counts. Experimental results on random and real problems show the benefits of this approach.
KeywordsLower Bound Constraint Satisfaction Problem Optimal Cost Opportunistic Specialization Frequency Assignment Problem
Unable to display preview. Download preview PDF.
- M. S. Affane and H. Bennaceur. A weighted arc consistency technique for Max-CSP. In Proc. of the 13th ECAI, 209–213, 1998.Google Scholar
- S. Bistarelli, U. Montanari and F. Rossi. Constraint Solving over Semirings. In Proc. of the 14 th IJCAI, 1995.Google Scholar
- J. Larrosa. Boosting search with variable elimination. In Proc. of the 6 th CP, 291–305, 2000.Google Scholar
- J. Larrosa. Node and arc consistency in Weighted CSP. In Proc. of the 18 th AAAI, 2002.Google Scholar
- J. Larrosa and P. Meseguer. Exploiting the use of DAC in Max-CSP. In Proc. of the 2 th CP, 308–322, 1996.Google Scholar
- P. Meseguer, M. Sanchez. Specializing russian doll search. In Proc. of the 7 th CP, 464–478, 2001.Google Scholar
- T. Schiex, H. Fargier and G. Verfaillie. Valued Constraint Satisfaction Problems: hard and easy problems. In Proc. of the 14 th IJCAI, 631–637, 1995.Google Scholar
- T. Schiex. Arc consistency for soft constraints In Proc. of the 6 th CP, 411–424, 2000.Google Scholar
- G. Verfaillie, M. Lemaître, and T. Schiex. Russian doll search. In Proc. of the 13 th AAAI, 181–187, 1996.Google Scholar