Author: Ross Boyd
Date: 05:13:47 08/24/03
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On August 23, 2003 at 02:18:33, Tim Foden wrote: >On August 23, 2003 at 01:53:11, Ross Boyd wrote: > >> >>btw, I don't mean the standard hashing that nearly everyone uses. >> >>I've heard a few people talking about EH but can't imagine what the idea is. >>Can someone enlighten me please... thanks! >> >>Ross > >Hi Ross, > >This is where you have a separate hash table that is used just by your >evaluation. When you call Evaluate() it looks in this hash table to see if it >has previously evaluated this position, and if so, it just returns the value. >Otherwise it does it's normal evaluation, saves it in the evaluation hash table, >and then returns the value. > >Depending on your evaluation function, this may or may not provide a speedup. > >Cheers, Tim. Thanks for explaining it. I thought it would be more elaborate than this. At first thought, I would imagine the normal hash table lookups would make an extra eval hash redundant. Perhaps the key to the eval hash is that the returned scores are not bounded in any way or tied to a depth and will always be used if found. I guess it would payoff most for really complex/slow evaluation functions. What size relative to a 64Mb TT would the eval hash be? Any idea? Thanks Tim, Ross
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