Author: José Carlos
Date: 06:48:53 10/18/00
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On October 18, 2000 at 09:13:13, Bas Hamstra wrote: >On October 18, 2000 at 08:06:23, David Rasmussen wrote: > >>I was wondering about a potential "bug" or at least "unwanted feature" of the >>way hashing and extensions affect eachother in, say, Crafty. >> >>The problem is basically this: >> >>In Crafty, whenever depth is used for other purposes than searching (that is >>hashing and nullmove), the extension factor isn't included. That means that a >>search that essentially asked for a depth=5 + extensions=3 == 8 ply search, will >>return with success from the hashprobe if the draft is just 6 or 7. Shouldn't >>the depth parameter ALWAYS be used with relevant extensions for the search to be >>(at least more) theoretically correct ? >> >>Am I making sense? > >I think I know what you mean. I store always as draft the depth that is actually >searched below this node. So if I normally would search 5 ply, but there is 1 >extension, this node is searched at 6 ply. So store draft=6. > >Now when the search asked for a 6 ply depth, and there was no extension, the >hashrecord with draft=6 could theoretically be returned. > >I believe Crafty does something different, that I too don't understand. > > >Regards, >Bas Hamstra. I think I don't understand you. When you say you store the depth that is actually searched below this node, do you mean the depth of the PV? Because there can be a lot of extensions in other branchs of the tree... I say I don't understand because: -you start a search for depth=5. -when the search returns, you get an actual depth of 6 due to a check extension in the PV. -then you store depth=6 in the hash table??? IMO, this is wrong, because if you reach that position again with depth=6 and use the value from the HT, you are actually missing a ply (the extra ply you'd extend if you searched the node). But, probably, I've misuderstood you both :( Regards, José C.
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