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Subject: Re: "Busting" computer engines and other pointless activities

Author: blass uri

Date: 07:07:56 05/11/00

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On May 11, 2000 at 08:33:26, Mogens Larsen wrote:

>On May 11, 2000 at 05:36:42, blass uri wrote:
>
>>I also believe that other beta testers did not think about part of my productive
>>ideas for chess programs.
>
>Out of curiosity, what productive ideas have you been suggesting?
>
>Sincerely,
>Mogens

I will repeat one idea that I posted here:


Many programs are null movers and they prune moves when they see no threat.

I found that Crafty could not find some tactics in practical games because it
pruned threat mate moves.

I suggested that before the decision if to prune by null move to check also if
there is a mate threat to bigger depth(If it seach d plies for regular threat it
can search d+1 or d+2 plies for mate threat)

I think this will help crafty to see tactics when there is a mate attacks and I
think that crafty will not be significantly slower when there is no mate threat
because checking if there is a d+1 plies mate threat is easier than checking if
there is a d plies not mate threat).

Crafty can call chest(a free program that is the best mate solver) to check if
there is a mate threat and chest is a very fast mate solver(it tries to prove
that there is no mate with the smallest possible tree and it helps it to see
that there is no mate very fast).

I read that it is a slow searcher and search only 20000 nodes per seconds on
a slow hardware p166(I am not sure if I am right about the hardware) but it can
solve 1500 mate in 2 in one second.


Crafty on p166 needs significantly more than 1/1500 second in order to search 3
plys threat when these threats can miss mate in 2 because crafty's evaluation
also has no idea if the position is mate so it may need more than 2d-1 plies to
see mate in d threat not only because of null move.

Uri



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