Abstract

Optimal planners in the classical setting are built around two notions: branching and pruning. SAT-based planners for example branch by trying the values of a selected variable, and prune by propagating constraints and checking consistency. In the conformant setting, a similar branching scheme can be used if restricted to action variables, but the pruning scheme must be modified. Indeed, pruning branches that encode inconsistent partial plans is not sufficient since a partial plan may be consistent and complete (covering all the action variables) and still fail to be a conformant plan. This happens indeed when the plan does not conform to some possible initial state or transition. A remedy to this problem is to use a criterion stronger than consistency for pruning. This is actually what we do in this paper where the consistency-based

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