Disjoint Pattern Database Heuristics

onlyaectsubgoalsinasinglegroup.Forexample,inthesliding-tilepuzzle,eachoperatoronlymovesonetile.Thisisjustasecientastakingthe
maximumofdierentvalues,butmuchmoreaccurate,andstilladmissible. mostlyduetothelatencyofrandomlyaccessingthelargedatabaseinmemory.Thisoverheadismorethancompensatedforbythedecreaseinthe
numberofnodesgeneratedtosolveaproblem. Patterndatabaseheuristicsaremoreexpensivetoevaluateduringsearch,
multiplesubgoals.Thisworksuggestsheuristicsbasedonthesimultaneous toapplyittootherproblems.Allcombinatorialproblemsinvolvesolving implementationofadmissibleheuristicfunctions.Theobviousnextstepis Itremainstobeseenhowgeneralthisapproachistothediscoveryand
addedtogethertocreateamoreaccurateadmissibleheuristic. considerationofmultiplesubgoals,insuchawaythattheirvaluescanbe
ThisworkwassupportedbyNSFGrantIRI-9619447.ThankstoEitan YardenandMosheMalinfortheirworkonpairwiseandtripledistances. 7 Acknowledgements
References
[2]Felner,A.,ImprovingSearchTechniquesandUsingthemonDierentEnvironments,Ph.D.Thesis,Dept.ofMathematicsandComputerScience,
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[4]Gasser,R.U.,HarnessingComputationalResourcesforEcientExhaustiveSearch,Ph.D.Thesis,SwissFederalInstituteofTechnology,Zurich,
Switzerland,1995.
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