Partial forward checking (PFC) may perform more consistency checks
than really needed to detect dead-ends in MAX-CSP. After analyzing
PFC, we have identified four causes of redundant check computation:
(a) unnecessary lookahead when detecting an empty domain, (b) not
always using the better bounds for future value pruning, (c) computing
in advance inconsistency counts, and (d) lookahead is performed on the
whole set of future variables. We present the partial lazy forward
checking (PLFC) algorithm, which follows a lazy approach delaying as
much as possible inconsistency count computation, keeping updated the
contribution of future variables to the lower bound. This algorithm
avoids the causes of redundant checks identified for PFC. It can be
easily combined with DACs, producing the PLFC-DAC algorithm. Empirical
results on random problems show that PLFC-DAC outperforms previous
algorithms in both consistency checks and CPU time.
CitationLarrosa, J., Meseguer, P. "Partial lazy forward checking". 1997.
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