Author: Brian Richardson
Date: 09:58:23 08/25/04
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On August 25, 2004 at 12:42:34, Volker Böhm wrote: > >Hi, > >the following position of the iq - test (position 166) cannot be solved from >spike in reasonalbe time (> 2h): > >r4r1k/6pp/3p3b/1p1Npb2/3nB2q/2N3P1/PP3P1P/R2Q1RK1 b - - 0 1 > >(The Move 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 (one move is not enough to show the mate thread thus going back >to window). > >I tested the position with fritz 8, he solves it in 8 ply in nearly no time. >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 I have two versions of Tinker that I have been experimenting with for some time. One is "regular" Tinker with full evaluation, and the other uses only pawn evaluation and some simple PCSQ terms (e.g., no king safety, etc). The search is the same in both versions. Regular Tinker solves this in a few seconds at 8 ply, and the "simple" Tinker does not after a long time. I suspect the difference is the king safety and not so much null move or pruning, at least for Tinker (which would normally lose to Spike anyway). Brian
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