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Subject: Re: Toga Clone

Author: Vasik Rajlich

Date: 05:31:27 03/10/05

Go up one level in this thread


On March 09, 2005 at 22:30:05, Alex Newman wrote:

>On March 09, 2005 at 22:10:58, Robert Hyatt wrote:
>
>>On March 09, 2005 at 21:19:51, Alex Newman wrote:
>>
>>>On March 09, 2005 at 21:12:52, Michael Yee wrote:
>>>
>>>>On March 09, 2005 at 20:27:09, Alex Newman wrote:
>>>>
>>>>>I can take the source code of Crafty and make an engine stronger then Crafty in
>>>>>less then a week.
>>>>
>>>>Not to be (too) confrontational, but have you actually accomplished this feat,
>>>>say, in a private experiment?
>>>>
>>>>There was someone here a while ago who was trying to get people to bet him a
>>>>large sum of money that he couldn't improve crafty by some amount of points
>>>>(maybe 100?).
>>>>
>>>>I'm skeptical of these kind of claims because if it were possible to improve
>>>>crafty by that much, it would almost be commercial strength (according to WBEC
>>>>ratings)... So why wouldn't that person just write a commercial-level engine
>>>>from scratch (given that he has the last "secrets" anyway)?
>>>>
>>>>Michael
>>>
>>>I didn't say 100 ELO. I just said 'improve'.
>>>No, I didn't try it. But try adding checks in quiescent, history and better
>>>futility pruning, and you should get at least 30 ELO.
>>>I think Crafty could be better in tactics.
>>
>>
>>1.  crafty uses history.  always has.
>>
>>2.  older versions used checks in q-search.  you can see from the comments in
>>main.c when they were removed.  The version with was absolutely no better than
>>the version without, and the code was simpler without.
>>
>>3.  "better futility pruning" I don't know about.  It is already risky enough,
>>but who knows what can be improved there...
>
>Thanks for the answer Prof. Hyatt. I have a great respect for you and Crafty.
>
>- By history pruning, I mean reducing search depth for moves with low history
>value (many conditions apply of course). I know Crafty uses history for move
>ordering, but am not aware you use it for pruning (didn't check the most recent
>Crafties).
>
>- It's seems to be common experience shared by many that checks in q-search help
>tactics, but again they shouldn't be done always. Some think that using always
>R=3 and checks in q-search for null moves only is a good idea.
>
>- By better futility pruning, I mean doing pruning for nodes other then leafs,
>but with much higher material margin.

Crafty's approach is better than it might look. Quite a bit of "intelligence" in
an engine is actually counterproductive ..

Vas



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