Author: Robert Hyatt
Date: 12:38:43 02/22/06
Go up one level in this thread
On February 22, 2006 at 12:19:59, Tom Likens wrote: >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 It is less about depth and more about time. It is getting this in 10 seconds using a single PIV 2.8 processor. Part of the delay is caused by having to escape the white checks with the black king, part probably caused by forward pruning...
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