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Subject: Re: Avoid perpetual check?

Author: Uri Blass

Date: 13:09:54 09/05/04

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On September 05, 2004 at 15:28:06, Ed Schröder wrote:

>On September 05, 2004 at 11:16:31, Uri Blass wrote:
>
>>On September 05, 2004 at 11:02:17, Ed Schröder wrote:
>>
>>>On September 04, 2004 at 17:22:40, Uri Blass wrote:
>>>
>>>>On September 04, 2004 at 17:06:50, Chris Welty wrote:
>>>>
>>>>>On September 04, 2004 at 17:01:40, Uri Blass wrote:
>>>>>
>>>>>>Movei does not use hash for pruning.
>>>>>>
>>>>>>Uri
>>>>>
>>>>>Interesting. Why not?
>>>>
>>>>I believe that using hash for pruning limit my possibiloities for improvement
>>>>with evaluation that is not dependent only on the leaf position and at this time
>>>>there are more important things to do then using hash for pruning.
>>>
>>>Excuse my ignorance but what is hash pruning?
>>>
>>>My best,
>>>
>>>Ed
>
>>It is what almost every program is using.
>
>I am pretty sure you are one of the only.
>
>
>>It is returning value based on hash tables because the position was already
>>searched in the past with bigger or equal depth.
>>
>>Movei is not using it and it is using hash tables only for order of moves and I
>>believe that it enable more possibilities for evaluation that is not based only
>>on the leaf position(for example movei can detect a lot of perpetual checks
>>without seeing the draw because it's evaluation suspect the draw after a lot of
>>checks so it gets closer to 0 when other programs cannot do it.
>
>>Of course detecting perpetual check faster is not the only idea that it can be
>>used for.
>
>Last time I checked hash-pruning is good for speedup factor of 2-3 in the
>midgame and much much more in the endgame. I think you should reconsider.
>
>My best,
>
>Ed

I do not think to reconsider(at least not in the near future).

I believe that there are a lot of ways to improve movei that contradict using
hash for pruning.

Of course detecting perpetual checks is not a good reason by itself to justify
not using hash for pruning.

Uri




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