Author: Uri Blass
Date: 09:28:33 10/21/03
Go up one level in this thread
On October 21, 2003 at 11:53:02, Tord Romstad wrote: >I don't run my engine through WAC very often, but before releasing a new >version (which I will do within a couple of days) I run the whole suite as >a sanity test. This time, the following position made me worried: > >[D]8/8/2Kp4/3P1B2/2P2k2/5p2/8/8 w - - bm Bc8; id "WAC146"; > >Previously, my program had no problems with this position. The new >version, which is the first one to include tablebase support, prefers >Bd3 instead of Bc8. At ply 21, the score is +12 for white. When I >disable tablebases, the program plays Bc8. > >Does Bd3 also win, or should I look for yet another bug? Bd3 is also winning and is one of the solutions 8/8/2Kp4/3P1B2/2P2k2/5p2/8/8 w - - bm Bc8 Bd3 Bh3; id "WAC.146"; > >One of the hardest positions in WAC for my engine is number 163: > >[D]5rk1/2p4p/2p4r/3P4/4p1b1/1Q2NqPp/PP3P1K/R4R2 b - - bm Qg2+; id "WAC163"; > >On a Pentium IV 2.4 GHz, I need 11 plies and 1m53s to find the winning move. Congratulations Your program is better than Shredder7.04 that cannot find it even after 13 plies Analysis on A1000 New game [D]5rk1/2p4p/2p4r/3P4/4p1b1/1Q2NqPp/PP3P1K/R4R2 b - - 0 1 Analysis by Shredder 7.04: 1...cxd5 2.Nxg4 Qxg4 3.Qxd5+ Kh8 ³ (-0.26) Depth: 1/5 00:00:00 1...cxd5 2.Nxg4 Qxg4 3.Qxd5+ Kh8 ³ (-0.26) Depth: 2/5 00:00:00 1...cxd5 2.Qxd5+ Kh8 3.Qe5+ Rff6 4.Qxc7 = (0.04) Depth: 3/8 00:00:00 1...cxd5 2.Qxd5+ Be6 3.Qe5 = (0.12) Depth: 3/10 00:00:00 1...cxd5 2.Qxd5+ Be6 3.Qe5 c6 = (0.07) Depth: 4/10 00:00:00 1...cxd5 2.Qxd5+ Be6 3.Qd1 Rf4 4.gxf4 Qxf2+ 5.Rxf2 ² (0.32) Depth: 5/17 00:00:00 1...cxd5 2.Qxd5+ Be6 3.Qd1 Rb8 4.Qxf3 exf3 5.Rfb1 ² (0.45) Depth: 5/17 00:00:00 1...cxd5 2.Qxd5+ Be6 3.Qd1 Qxd1 4.Nxd1 Bd5 ² (0.48) Depth: 6/18 00:00:00 37kN 1...cxd5 2.Qxd5+ Be6 3.Qd1 Qf6 4.a4 Qxb2 5.Ng4 Rg6 ² (0.51) Depth: 7/18 00:00:01 111kN 1...Rd6 2.Rad1 Kh8 3.dxc6 Rxd1 4.Qg8+ Kxg8 ² (0.50) Depth: 7/18 00:00:01 145kN 1...Rd6 2.Rad1 Kh8 3.Qc4 Bd7 4.Qc3+ Rff6 5.a3 cxd5 6.Nxd5 ² (0.47) Depth: 7/18 00:00:01 161kN 1...Rd6 2.Rad1 Kh8 3.Qb7 Rxd5 4.Nxd5 cxd5 5.Rg1 ² (0.48) Depth: 8/23 00:00:02 322kN 1...Rd6 2.Rad1 Kh8 3.a4 cxd5 4.Rxd5 Qe2 5.Qc3+ Kg8 6.Rg5+ Rg6 7.Qb3+ Kh8 ² (0.60) Depth: 9/23 00:00:04 664kN 1...cxd5 2.Qxd5+ Be6 3.Qd1 Qf6 4.Qc2 Rg6 5.a4 Qe5 6.Qc3 Qxc3 ² (0.59) Depth: 9/26 00:00:05 747kN 1...cxd5 2.Qxd5+ Be6 3.Qd1 Qf6 4.Qc2 Rb8 5.b3 Qe5 6.Rad1 Rg6 ² (0.46) Depth: 9/26 00:00:06 918kN 1...cxd5 2.Qxd5+ Be6 3.Qd1 Qxd1 4.Nxd1 Rhf6 5.Re1 Bg4 6.a4 Bxd1 7.Raxd1 Rxf2+ 8.Kxh3 Re8 ² (0.35) Depth: 10/28 00:00:10 1523kN 1...cxd5 2.Qxd5+ Be6 3.Qd1 Rhf6 4.Rc1 Bxa2 5.Rxc7 Qxd1 6.Nxd1 Bb3 7.Kxh3 Bxd1 8.Rxd1 Rxf2 = (0.17) Depth: 11/32 00:00:20 3257kN 1...cxd5 2.Qxd5+ Be6 3.Qd1 Rhf6 4.a4 Qxd1 5.Nxd1 e3 6.Nxe3 Rxf2+ 7.Rxf2 Rxf2+ 8.Kg1 Rxb2 ² (0.29) Depth: 12/37 00:00:38 6038kN 1...cxd5 2.Qxd5+ Be6 3.Qd1 Rhf6 4.a4 Qxd1 5.Nxd1 e3 6.Kg1 Bc4 7.Nxe3 = (0.04) Depth: 13/37 00:01:26 13252kN 1...cxd5 2.Qxd5+ Be6 3.Qb5 Bc8 4.Qd5+ Qf7 5.Qxf7+ Rxf7 6.Kh1 Ba6 7.Ng4 Kg7 8.Nxh6 = (0.03) Depth: 13/38 00:03:27 32739kN (Blass, Tel-Aviv 21.10.2003) >The problem is to find the line 1... Qg2+ 2. Nxg2 hxg2+ 3. Kxg2 Bf3+ 4. Qxf3 >exf3+ 5. Kg1 Rf5! followed by Rfh5. Without nullmove pruning, this position >is solved within a few seconds. > >This is rather annoying, as I have lost more games than I would like on >the ICC because of missing similar tactics. Are there any inexpensive >tricks to help me solve this kind of positions more quickly? > >Tord Yes Movei has no problem to solve it after 7 plies because it can see a threat thanks to smaller king safety evaluation(it does not see a mate threat but the threat that it see is enough not to prune). Uri
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