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Subject: Re: Q for programers

Author: Steffen Jakob

Date: 00:15:36 04/30/02

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On April 29, 2002 at 16:06:31, José Carlos wrote:

>On April 29, 2002 at 15:52:32, Scott Gasch wrote:
>
>>On April 29, 2002 at 14:01:23, Joe McCarro wrote:
>>
>>>If I were playing someone over the board and they seemed to give me a
>>>possibility to play Bxa1 snatching the rook I would think long and hard before
>>>doing that. I'd figure as long as this isn't a trap I will win the game.  Let me
>>>take my time to just make sure its not a trap. I wonder if this couldn't be
>>>programmed in.  Anytime the other player makes what on the surface appears to be
>>>a blunder (e.g., drops over a pawn) the computer could spend extra time working
>>>out the position before moving.  If it ended up it was in fact just a blunder
>>>presumably the computer should still be able to win despite the extra time spent
>>>looking for the tactical shot.  If it found it wan't a blunder the computer
>>>might avoid taking the poison.  Do the programmers do anything like this?  Would
>>>this in fact be helpful or would it have disadvantages as well?
>>
>>This idea could certainly be programmed.  But there's a problem.  Let's assume
>>the engine is playing a blitz game and has allocated itself 10 seconds to think
>>about a move.  In 10 seconds it gets to depth d and realizes that the move it
>>wants to make seems to "win".  To get to depth d+1 will a long time, maybe 10
>>more seconds or so.  To get to depth d+2 may take 10 + 20 more seconds
>>(sometimes more).
>>
>>So my point is, to say "this position is important, I should think about it a
>>bit more" is fine... but to think about it even just a little bit more may take
>>a really long time.  The question is whether its a good use of the engine's
>>allotted time.  Maybe.
>>
>>Personally, I do some tricks with time allocation but nothing as direct as the
>>idea you suggest.  I consider it just too expensive, especially at fast time
>>controls.
>>
>>Scott
>
>  Some time ago I (Averno) was playing Hossa on ICC. Hossa took a long time to
>reply a quite normal move and Steffen told me Hossa extended time when there was
>a big jump (up or down) in the score, exactly with the above stated idea.
>  I'm not quite sure about it, but it'd be certainly interesting if Steffen
>himself could tell us his experience with that time extension.

Hossa is a slow searcher. Most of the time he gets outsearched against other
comps. Therefore it doesnt happen very often that a computer opponent blunders
away material which Hossa sees very quickly. Instead it is likely that in a
deeper search the score will drop and also playing the obvious move from the
shallow search would lose. Therefore Hossa extends the time there. Of course I
consider how much time I have overall, if there is an increment, how big the
score increment was etc. The idea is simple: 1. if it was really a blunder then
I will win anyway. 2. If it was a trap-like move then thinking deeper might safe
my life (which happens rather often!). I think adding this was an improvement
for Hossa. This might not be true for other engines which dont get outsearched
as often as Hossa.

Best wishes,
Steffen.



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