Author: Stuart Cracraft
Date: 20:51:50 08/25/04
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On August 25, 2004 at 12:58:23, Brian Richardson wrote: >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 Can you be more specific about regular Tinker's king safety? What specifically does it have? Stuart
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