Author: Volker Böhm
Date: 11:01:38 08/25/04
Go up one level in this thread
On August 25, 2004 at 13:54:27, Stan Arts wrote: >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 Thanks for the hint. You are right. Spike does not score pressure on the king very much if no queen is present. On top the queen has a high score (960 cp). Reducing the score of the queen solves the position. Thus no "fault" of the search. As this is the only position in iq-test spike does not solve in less than 10 minutes I thought I had found a "hole" in search. Greetings Volker
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.