Author: James Swafford
Date: 10:31:16 05/29/04
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On May 29, 2004 at 12:09:56, Volker Böhm wrote: >On May 29, 2004 at 11:10:47, James Swafford wrote: > >>In a recent post, Tord suggested setting a flag in >>the search when the hash table suggests a fail high, and >>testing whether the search would indeed fail high. >> >>The idea seems so simple I'm embarassed I haven't thought >>of it before. :) >> >>I've been 'pretty sure' for a long time that I've got some >>nasty hash bugs. I'm in the mood to exterminate them. >> >>Last night I implemented Tord's idea and, to my dismay >>(but not to my surprise) my hash table is saying 'fail >>high' when the search wouldn't have failed high. And- >>it doesn't take very long. :) >> >>This seems like a nasty thing to debug. I'm comtemplating >>how I might go about it. I'm hoping some of you can >>provide some suggestions... >> >>-- >>James > >The hash table could say fail high and the search not fail high because of >search instability. Search instability arises from hash entries, nullmoves, >foreward-prunings and extensions. >Thus you have to turn those off to be sure its a bug. > Without any sort of pruning,nullmoves, or extensions, it still happens (though it does take much longer). Would you not consider this a bug? -- James >Greetings Volker
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