Author: Stan Arts
Date: 10:54:27 08/25/04
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On August 25, 2004 at 13:41:18, Volker Böhm wrote: >On August 25, 2004 at 13:06:40, Álvaro Begué wrote: > >>On August 25, 2004 at 12:52:46, Volker Böhm wrote: >> >>> >>>Hi, >>> >>>the following position of the iq - test (position 166) cannot be solved from >>>spike in reasonalbe time (> 2h): >>> >>>[D]r4r1k/6pp/3p3b/1p1Npb2/3nB2q/2N3P1/PP3P1P/R2Q1RK1 b - - 0 1 >>> >>>(The move to find is Qxe4) >>> >>>The reason is a nullmove-problem. After the queen-sac there are many moves that >>>leads to a mate-thread. But one queen back spike tends to prune because of >>>nullmove result. >>> >>>I tested the position with fritz 8, he solves it in 8 ply in nearly no time. >>>(PRODEO NEEDS 7 Ply, Ruffian 1.01 11 Ply). >>> >>>Are there non commercial engines that solves this position too in a short amount >>>of time? >>>Maybe the author of this engine would be so kind to explain the rule that solves >>>the nullmove-problem. >>> >>>Thanks Volker >> >>Ruy-Lopez solves it in depth 8, in under 30 seconds. > >Do you know if Ruy-Lopez has a special rule to skip nullmove-prunings in such a >position? > >Greetings Volker But this position seems very dependant on static evaluation. Have you tried forcing Qxe4 to see if Spike really doesn't see it, or just prefers another move instead, that it scores slightly better. (The program needs to score mobility and pressure on the king and so considerably, I guess. Before it'll choose Qxe4) There seems no clear short-term tactical win. (is there?) Greetings and goodluck Stan
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