Author: Robert Hyatt
Date: 20:08:14 08/07/01
Go up one level in this thread
On August 07, 2001 at 16:42:27, Alvaro Jose Povoa Cardoso wrote: >Do you still have the ETC version of Crafty? No. But here is what you need: 1. A function that will compute a updated hash key given a specific move. This is needed to avoid the MakeMove() overhead that will arise when running thru the move list to find if any of the resulting positions are hash hits. 2. A simple ordering function that takes the move list, makes them one at a time, and probes the hash table to see if you get a hit and that hit will be an exact score that causes a cutoff, or if it will directly cause a cutoff. If so, that is the move you try first at this ply. >If not could you post the ETC code/pseudocode, if that is not asking too much? >I know the net result of implementing ETC is null, but I think my program >(checkers) could benefit more than chess programs from ETC (at least I would >like to test). >I'm confused with ETC. Taking Crafty as the example, should we use HashProbe() >with ETC or should we make a special version of HashProbe() that does not >changes alpha and beta since all we want is the hash score? >Correct me if I'm wrong: >When using ETC, after making each move we should probe the hash table for the >opposite side right? Yes, as you are effectively "making" a move. >So instead of > HashProbe(tree,ply,depth,wtm,&alpha,&beta,&mate_threat) >we should do > HashProbe(tree,ply,depth,ChangeSide(wtm),&alpha,&beta,&mate_threat) > >Cutoffs should be done if the hash score >= BETA right? >When probing the hash table for ETCs should we consider >Upperbounds/Lowerbounds/Exactscores or >sould we simply use the hash score? > > >Thank you, >Alvaro Cardoso
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