Author: Uri Blass
Date: 10:06:27 02/22/06
Go up one level in this thread
On February 22, 2006 at 11:47:10, Robert Hyatt wrote: >On February 22, 2006 at 11:33:17, Stuart Cracraft wrote: > >>[D]8/7p/5k2/5p2/p1p2P2/Pr1pPK2/1P1R3P/8 b - - >> >>Hi - this is WAC #2 and a position my program can't solve. >>The solution is Rxb2. >> >>How to make a program solve this problem in a way that carries over >>to the similar class of positions? >> >>In the printout below, score is in millipawns. >> >>.ts >>position file? [wac.epd] wac.epd >># of test positions to test? 1 >>maxtime = 99999900 >>Interrupt current ply and return move at timeout >>Testsuite: Tests/wac.epd 1 positions >>*** Problem Solution(s): Rxb2 (bm) >>-- ** -- ** -- ** -- ** >>** -- ** -- ** -- ** BP >>-- ** -- ** -- BK -- ** >>** -- ** -- ** BP ** -- >>BP ** BP ** -- WP -- ** >>WP BR ** BP WP WK ** -- >>-- WP -- WR -- ** -- WP >>** -- ** -- ** -- ** -- >>mv 1 stage 0, black to move, computer plays black >>hash=a5e05373307344c6 >>0 0 0 0 0 0 >>Alpha=2627 Beta=3428 Maxdepth=9999999 MaxTime=99999900 xboard=0 >>Itr/Max Mv Score Time Nodes PV >> 1/ 1> b3b2 3428 0.00 2 b3b2 >> 1/ 1 c4c3 3357 0.01 20 c4c3 >> 2/ 4< c4c3 2956 0.01 44 c4c3 d2d3 >> 2/ 4 f6g7 38 0.01 106 f6g7 >> 3/ 6 c4c3 8 0.02 493 c4c3 d2d3 >> 4/ 9 f6e7 12 0.04 1204 f6e7 f3g2 b3b6 >> 5/14 h7h5 21 0.08 3400 h7h5 f3f2 f6g7 >> 6/14> f6e6 421 0.14 6731 f6e6 f3g2 c4c3 d2d3 b3b2 g2h1 >> 6/14 f6e6 421 0.16 7677 f6e6 f3g2 c4c3 d2d3 b3b2 g2h1 h7h6 >> 7/15 c4c3 26 0.30 16084 c4c3 b2c3 b3c3 d2a2 h7h5 f3g3 >> 8/15> c4c3 426 0.43 23680 c4c3 b2c3 b3c3 d2a2 f6e6 h2h4 c3c4 >> 8/15 c4c3 934 0.60 34786 c4c3 b2c3 b3c3 d2b2 c3a3 b2b7 f6g6 >> 9/16< c4c3 533 0.89 51904 c4c3 b2c3 b3c3 d2b2 c3a3 b2b7 f6g6 b7b6 g6g7 >>b6b7 g7h8 f3g2 a3a2 >> 9/18 f6e7 15 1.90 116795 f6e7 d2d3 c4d3 h2h4 mtmt >>10/21 b3b6 15 5.66 349319 b3b6 >>11/25 c4c3 25 20.19 1107635 c4c3 b2c3 b3c3 d2b2 c3a3 b2b7 f6g6 b7h7 >>12/29 c4c3 48 78.46 4098861 c4c3 b2c3 b3c3 e3e4 c3a3 f3e3 a3b3 d2d3 b3b2 >>13/33 b3b8 27 555.50 30561813 b3b8 e3e4 b8g8 f3e3 f5e4 e3e4 g8g4 d2d3 c4d3 >>e4d3 >> >>Thanks, >> >>Stuart > >Crafty gets this at depth 15 because it sees the promotion of a black pawn: > > 15 6.96 -2.31 1. ... c3 2. bxc3 Rxc3 3. e4 fxe4+ > 4. Kxe4 Rxa3 5. Rb2 Rb3 6. Rxb3 axb3 > 7. Kxd3 Kf5 8. Kc3 Kxf4 9. Kxb3 h6 > 10. Kc3 > 15 10.83 -1 1. ... Rxb2!! > 15 11.35 -3 1. ... Rxb2!! > 15 12.42 -3.99 1. ... Rxb2 2. Rxb2 c3 3. Rb6+ Ke7 > 4. Rb7+ Kd6 5. Rb6+ Kc7 6. Rb4 c2 7. > Rc4+ Kb6 8. Kg3 d2 9. Rxc2 d1=Q 10. > Rc8 > 15-> 14.26 -3.99 1. ... Rxb2 2. Rxb2 c3 3. Rb6+ Ke7 > 4. Rb7+ Kd6 5. Rb6+ Kc7 6. Rb4 c2 7. > Rc4+ Kb6 8. Kg3 d2 9. Rxc2 d1=Q 10. > Rc8 > 16 16.39 -4.19 1. ... Rxb2 2. Rxb2 c3 3. Rb6+ Ke7 > 4. Kf2 c2 5. Rc6 d2 6. Rxc2 d1=Q 7. > Rc7+ Kd6 8. Rxh7 Qd2+ 9. Kf3 Qd5+ 10. > Ke2 Qa2+ 11. Kd3 Qxa3+ 12. Kd4 > >The above on a single-cpu 2.8ghz PIV. > >I think this is really more about tactics than about any evaluation tricks... seeing the 2.31 score of crafty for c3 it may be possible that c3 is also winning. I think that even if c3 is winning it is not alternative solution because I expect every strong program to find Rxb2 but based on Dann Corbit it is considered in that case as an alternative solution. Uri
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