Disjoint Pattern Database Heuristics
Disjoint Pattern Database Heuristics
Disjoint Pattern Database Heuristics
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
tiles,wewanttogrouptogethertilesthatareneareachotherinthegoal partoftheindextothedatabase.Asageneralrule,whenpartitioningthe entries,whichrangefrom0to38moves.Inneithercaseistheblankposition rangefrom0to33moves.Theeight-tiledatabasecontains518;918;400<br />
state,sincethesetileswillinteractthemostwithoneanother.<br />
Figure4:<strong>Disjoint</strong><strong>Database</strong>forFifteenPuzzleanditsReection<br />
4.1 4 ExperimentalResults<br />
Wefoundalloptimalsolutionsto1000randomFifteenPuzzleprobleminstances,usingIDA*withavarietyofheuristics.Theaverageoptimalsolution<br />
lengthoftheseinstancesis52.522moves,andtheaveragenumberofoptimal<br />
instancetondtherstoptimalsolution.Thethirdcolumndisplaysthe solutionsis15.9.Table1showstheresults.Therstdatacolumnshows<br />
averagespeedofthealgorithm,innodespersecond,ona440MegaHertz secondcolumngivestheaveragenumberofnodesgeneratedperproblem theaveragevalueoftheheuristicfunctionoverthe1000initialstates.The<br />
instance. averagenumberofnodesgeneratedtondalloptimalsolutionstoaproblem time,inseconds,tondtherstoptimalsolution.Thelastcolumngivesthe SunUltra10workstation.Thefourthcolumnindicatestheaveragerunning<br />
cally,thelinear-conictheuristicwastherstsignicantimprovementover Manhattandistance[5].Itappliestotilesintheirgoalroworcolumn,but secondrowisforManhattandistanceenhancedbylinearconicts.Histori-<br />
TherstrowgivesresultsfortheManhattandistanceheuristic.The<br />
statecontainsthetiles(21)inthatorder,butinthegoalstatetheyappear reversedrelativetoeachother.Forexample,assumethetoprowofagiven 10
Change language