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Subject: Re: Endgame

Author: Mike Hood

Date: 08:09:34 11/10/03

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On November 10, 2003 at 09:31:50, Bob Durrett wrote:

>On November 10, 2003 at 05:00:20, José Carlos wrote:
>
>>On November 10, 2003 at 04:44:10, Jouni Uski wrote:
>>
>>>Hard for Ruffian (P4 2,4 GHz), not found in 20 minutes, BUT after executing
>>>move sees very fast, that white is mated! Null move problem?
>>>
>>>Jouni
>>
>>  I don't know for Ruffian, but I guess it's the same reason than for my
>>program: in the initial position, the program must search a lot of moves of
>>queen and rook, so it takes a while to search deep enough, but if you take the
>>rook, gxf3 is forced and then there's a pawn ending, where it's much faster to
>>search very deep.
>>  My program Anubis finds it in ply 22 after forcing Qxf3, very quicky, but from
>>the initial position, after some minutes, it's still in depth 16, so it will
>>take a long time to get the needed 23 plies (probably less due to extensions,
>>maybe like 20 or 21).
>>
>>  José C.
>
>Since chess engines in general are supposed to be weak at finding sacrificial
>lines, perhaps the programmers should do something to minimize the problem.  In
>this case, having the sacrifice looked at first might have saved some time.
>
>Bob D.

The main problem with this idea is that sacrifices are normally bad, rarely
good; and if a sacrifice IS good, a deep search is needed to find the benefits.
So a lot of computational time will be spent on searching for something that in
99.9% of positions isn't there.

The only alternative would be a revolutionary AI algorithm. I always try to
think of a chess program that uses similar thought processes to myself. When I'm
in the chess club I only consider sacrifices when I'm desperate, ie when my
position is so bad that I think something like "I'm pinned in... I'm gonna
lose... so I'll swap my Rook for two Pawns and get some momentum back into the
game". I'm not saying a chess program should have a "desperation algorithm", I'm
just saying that in some special circumstances it might search in ways it
wouldn't usually. But I admit that I'm just thinking aloud. Feel free to discard
my ideas as idealistic nonsense :)



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