Author: Tom Likens
Date: 09:19:59 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... Hey Bob, I'm surprised it takes Crafty to ply 15 to recognize the rook sacrifice, (usually this gets picked up around ply 12). I haven't looked at Crafty in some time, but this seems to imply that you've reduced the extensions in the latest version. Of course, that isn't necessarily a bad thing, just interesting. regards, --tom
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