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Subject: Re: Couple of chess programming questions

Author: Omid David

Date: 11:21:33 09/10/02

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On September 10, 2002 at 14:09:47, Dann Corbit wrote:

>On September 10, 2002 at 13:59:26, Omid David wrote:
>[snip]
>>Has anyone compared NegaScout vs. MTD(f) on a set of tactical test suites? It
>>seems to be interesting to test the behavior of MTD(f) in real complicated
>>positions.
>
>I think that the quiet positions will be a lot more interesting.  That is where
>the games are really won or lost anyway.
>
>Most chess moves in a game are quiet moves.  How often do you see the eval shoot
>up a full pawn?  Before the game is clearly won, maybe once or maybe not at all.
> The major meat of the game is manuvering into a position where you can perform
>that tactical shot.

Finding the good quiet move has to do largly with the evaluation function. In
such positions, searching one ply deeper is usually less important than having a
better eval function, and thus, a better understanding of the position. So,
while quiet positions are good means for general testing of programs, they
aren't of any great use for pure comparison of different algorithms against each
other.

But in tactical positions, the determining factor is the search depth, so the
algorithm which results in a smaller search tree will fair better. As Vincent
pointed out, there is some evidence that MTD(f) behaves worse than NegaScout in
complicated positions. So, IMO, conducting some experiments on tactical test
suites can help clear up some differences between MTD(f) and NegaScout's search
tree behavior.

Omid.





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