Author: David Rasmussen
Date: 14:04:36 12/05/01
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On December 05, 2001 at 16:41:22, Sune Fischer wrote: >>>> >>>>We need Bob or some other third party to make tests too I think. >>> >>>I have already done this. In fact, anyone that _doesn't_ do this is inviting >>>great grief. It is essential that the hashed information match _exactly_ the >>>computed information for every position. And I do this as part of my debugging >>>from time to time, which will often catch a bug where I forget to stick >>>something in the pawn hash record, but I use it later anyway. >> >>I agree, I am doing the same thing with Chezzz. Among a _lot_ of other debugging >>checks as well. Chezzz has roughly the same amount of collisions as Crafty, if I >>use 32-bit pawn hashkeys instead of 64-bit ones. >> >>/David > >I agree, but just because the hashed information doesn't match exactly the >computed information doesn't mean you have a collision, it _could_ be something >else. You are debugging a lot of stuff by doing this, any number of things could >be the cause. > >Collisions are much easier to detect directly using the 64 bit key for a >reference. > Not at all. I am _not_ debugging a lot of stuff by doing this. What "something else" would that be? I'm afraid you don't understand how it works then. If it reassures you, Bob does the same thing to check for collisions. We don't find _all_ collisions, as some positions just might happen to have the same score and properties in Crafty as some other position that has the same hashkey. But when we find a position that has the same pawn hashkey as some other position (as I have done), there is by definition a collision. /David
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