10.9.9 Statistics Predicates

The following predicates can be used to access execution statistics.

fd_statistics

fd_statistics(?Key, ?Value)

This allows a program to access execution statistics specific to this solver. General statistics about CPU time and memory consumption etc. is available from the built-in predicate statistics/2.

Without arguments, displays on the standard error stream a summary of the following statistics, and zeroes all counters. With arguments, for each of the possible keys Key, Value is unified with the current value of a counter, which is simultaneously zeroed. The following counters are maintained:

propagations   since release 4.10.0

The number of times a constraint was resumed.

entailments

The number of times a (dis)entailment was detected by a constraint.

prunings

The number of times a domain was pruned.

backtracks

The number of times the search has backtracked to an alternative branch.

restarts   since release 4.10.0

The number of times the search has restarted from scratch.

solutions   since release 4.10.0

The number of times the search has found an intermediate (for optimization problems) or final (for satisfaction problems) solution.

optimalities   since release 4.10.0

The number of times the search has proven optimality (for optimization problems) or found all solutions (for satisfaction problems).

propagators   since release 4.10.0

The number of propagators created.

variables   since release 4.10.0

The number of domain variables created.