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Subject: Re: I don't use illegal moves EVER

Author: blass uri

Date: 06:22:23 11/27/99

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On November 27, 1999 at 08:51:43, Heiner Marxen wrote:

>>How many nodes(legal moves) does your program search per second?
>
>Not even 20K NPS on a P/166, so CHEST is not a fast searcher.
>But at the same time it can do 1500 "mate in 2" per second.

Simple calculation shows that it needs only 20000/1500=13.333 nodes to find if
there is a mate in 2.

I do not understand it.
only generating all the legal moves in the first ply is more than it and I do
not understand how can you avoid it in cases when there is no mate in 2.

Even if there is a mate in 2 and you are lucky to guess the right move by first
try if you check all the legal moves of the opponent you usually have more than
13.333 legal moves.

I can understand saving nodes in the last ply when you need only to generate
moves that threat the king but how do you do it before the last ply?

Uri



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