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Subject: Re: Am I a null move searcher? :)

Author: Ralf Elvsén

Date: 17:24:41 04/01/01

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On April 01, 2001 at 20:02:14, Jeroen van Dorp wrote:

>As you are aware of the fact I know nothing about chess programming, I wonder if
>the following behaviour has something to do with the way a chess engine is
>programmed.
>
>It's this position:
>[D]8/kp6/4p3/p2p1p2/P1nP1P2/2PK2R1/7q/1Q6 w - - 0 1
>
>This is the way I assessed the situation:
>Black threatens mate at d2 in the next move.
>White has to counter this by neutralizing the threat and simultaniously defend
>its rook. So the most logical way is playing 1. Qe1
>I guess I'm thinking like a null-move searcher.
>
>So I asked Fritz 6 and it came up with the same solution until after some time
>it found the escape route for white to a draw/stalemate, namely 1. Qxb7+ Kxb7
>2.Rg7+.
>
>My question is: did Fritz start off with pondering over Qe1 because it is a
>"null-mover" or am I just talking nonsense and has this nothing to do with
>programming techniques?

It didn't choose Qe1 first because it's a null-mover. It doesn't do
nullmoves at the root I assume... And even if it did somehow that wouldn't
decide the first move to look at.

If this had been a position in the search tree it would have thought
(as a nullmover):

"If I (white) don't do anything, can black still not get a good enough
(according to some criterion) position?

Oops, I got mated, I better find a move. Lets see, Rg4... no, Qa1... no,
Qe1.. seems possible..." ...etc...

>
>The background is of course searching for or construction of positions like this
>to fool real people and computer programs alike.
>
>Thanks for the (expert) advice.

You didn't get any... :)

Ralf

>
>J.
>
>btw the position comes from Murej-Pawlenko (Moscow 1961) and you can find it in
>the "Chess Endgames" book from Laszlo Polgar (pos 894, p.171)



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