The TorchLight Tool: Analyzing Search Topology Without Running Any Search

The ignoring delete lists relaxation is of paramount importance for both satisficing and optimal planning. In earlier work [Hoffmann, JAIR’05], it was observed that the optimal relaxation heuristic h has amazing qualities in many classical planning benchmarks, in particular pertaining to the complete absence of local minima. The proofs of this are hand-made, raising the question whether such proofs can be lead automatically by domain analysis techniques. The TorchLight tool answers this question in the affirmative. TorchLight is based on a connection between causal graph structure and h topology. It distinguishes between global analysis and local analysis. Global analysis shows the absence of local minima once and for all, for the entire state space of a given planning task. Local analysis computes what we call the success rate, which estimates the percentage of individual sample states not on local minima and thus allows to make finer distinctions. Finally, diagnosis summarizes structural reasons for analysis failure, thus indicating domain aspects that may cause local minima. TorchLight Results Overview lo ca l m in im a ed < = c