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Subject: Re: IQ-Test Position 166, any hint how to solve it ?

Author: Alessandro Scotti

Date: 13:49:44 08/25/04

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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):
>
>r4r1k/6pp/3p3b/1p1Npb2/3nB2q/2N3P1/PP3P1P/R2Q1RK1 b - - 0 1
>
>(The move to find is Qxe4)

On my Athlon 700 MHz my program finds the move in less than 12 seconds with a
small score but then sticks to it and the score grows:

PV: 7 25 150 0 Qg4 Qxg4 Bxg4 Nf6 gxf6 Bxa8 Rxa8
PV: 8 40 435 0 Qg4 a3 Rae8 Qxg4 Bxg4 Nc7 Re7 N3xb5
PV: 9 35 809 0 Qg4 a3 Qxd1 Raxd1 Bg4 Rxd4 exd4 Nxb5 Bc1
PV: 9 40 1138 0 Qxe4 Nxe4 Bxe4 Nc3 Bf3 Qd3 b4 Nb1 Ne2+ Qxe2
PV: 10 55 1627 0 Qxe4 Nxe4 Bxe4 Nc3 Bf3 Qd3 b4 a3 bxc3 Qxc3
PV: 11 135 4375 0 Qxe4 Nxe4 Bxe4 Nc7 Bf3 Qxd4 exd4 Nxa8 Rxa8 Rfe1
PV: 11 165 5756 0 Qxe4 Nxe4 Bxe4 Nc3 Bf3 Qb1 b4 Re1 bxc3 bxc3

Queen value is 900 here, if I switch to the second set where the value is 1100
then the move is not found. For the null move, here are the program stats after
60 seconds:

Calls to GenMoves      : 615110
Calls to Evaluation    : 11109295
Null move cutoffs      : 490300 / 571726 (85.7%)
Nodes searched         : 23459999
Positions generated    : 11070319
Positions tried invalid: 755979
Hash probes failed     : 2368441 / 11430883
Pawn hash probes failed: 148926 / 11109295
Pawn hash stores       : 297852
Failed high at 1st try : 88.0%
Failed high at 2nd try : 04.5%

test: ended in 59996 ms



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