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Subject: Re: Toga Clone

Author: Anthony Cozzie

Date: 20:13:30 03/09/05

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.

1. History pruning does NOT seem like a good idea.  The history table is
completely unrelated to the current position, and yet you want to prune based on
it?

2. I personally use & like checks in q-search, but IMO its also possible to take
the nodes saved by not doing them and put them into recap+mate extensions.

3. Futility pruning only works with complete beancounters that have total
positional terms of 1/2 pawn or so.  Plus, Bob already does lazy eval.

IMO you aren't going to get 100 elo (or even 40) with search tricks.  You would
have to improve the evaluation, which is the primary area where it fails in
comparison to the commercials.  Which is obviously doable (Shredder & Fritz are
doing something right) but not exactly 1 week's worth of work . . .

anthony



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