Author: Uri Blass
Date: 02:53:59 09/27/00
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On September 27, 2000 at 04:21:52, Dieter Buerssner wrote: >On September 26, 2000 at 16:51:33, Uri Blass wrote: > >>[D]3r3k/p7/1p6/2p2Q1p/2P1R3/2P5/P2KP3/6q1 w - - 0 1 >> >>Hiarcs played Kc2 and had to resign some moves later because the queen cannot be >>saved[the game continued Kc2 Qd1+ Kb2 Rd2+ Ka3 Qc1+ Ka4 b5+ cxb5 Qc2+ Ka5 Qxc3+ >>and white resigned because of the line Ka6 Rd6+ Kb7 Qg7+ Kb8(forced because Kc8 >>is leading to mate) Rd8+]. >> >>How much time do programs need to avoid this tactical error?(some program like >>hiarcs can play Rd4 after a short time but later change their mind to Kc2 so the >>right test is to give them at least some minutes) > >Interesting position. I think, it is not unlikely for many engines to switch >moves here. It needs some relatively deep search to see that the queen is lost. >Before this, Yace sees tactical strong lines after Kc2, but in between, at just >one depth, they seem to be refuted. > >Yace needs 64 seconds on AMD K6-2 475 MHz, 30MB hash. >[...] > 8756 0.131 -1.43 4t : Re4d4 Rd8xd4+ c3xd4 Qg1xd4+ Kd2e1 Qd4c3+ Ke1f2 > Qc3xc4 Qf5xh5+ Kh8g8 [-100] >[stays with Rd4 until] > 3464157 16.90 -0.66 10t : Re4d4 Rd8xd4+ c3xd4 Qg1xd4+ Kd2e1 Qd4h4+ Ke1f1 > Qh4xc4 Qf5xh5+ Kh8g8 Qh5e8+ Kg8g7 Qe8e5+ Kg7g6 > Qe5d6+ Kg6f5 Qd6d7+ Kf5e5 Qd7xa7 Qc4c1+ Kf1f2 > b6b5 [0] >[...] > 9973064 53.77 -0.36 10t : Kd2c2 Qg1d1+ Kc2b2 Rd8d2+ Kb2a3 Qd1c1+ Ka3a4 > b6b5+ c4xb5 Qc1c2+ Ka4a5 Qc2xc3+ Ka5a6 Rd2d6+ > Ka6b7 Qc3g7+ Kb7c8 Qg7g8+ Kc8b7 Rd6b6+ Kb7c7H > Qg8b8+H Kc7d7H Rb6d6+H Kd7e7H <HT> [0] I do not understand the score of -0.36 When I look in the final position of the pv even without searching deeper I evaluate it as a very big advantage for black. Reasons: 1)The white king is in a very bad square and I am afraid from mate even before seeing it by search(it is a problem when the sides have queen and rook that is often enough to mate). 2)black is the attacker(it is black to move and black is not in check) I define the attacker as the side to move unless the side to move is in check. It seems to me that a better piece square table with big positional scores can help to have a better evaluation. I do not unsderstand the reason that a lot of programs evaluate the final position of the pv as almost equal. Here is the final position of the pv [D]1q5k/p3K3/3r4/1Pp2Q1p/4R3/8/P3P3/8 b - - 0 1 evaluation of programs at depth 1: CometB20 1.61: pawns for black Exchess3.14: 0.91 pawns for black Junior5.9:0.79 pawns for black crafty17.11:0.34 pawns for black Fritz5.32:0.22 pawns for black Some programs like hiarcs or doctor can see mate by search (unfortunately I cannot tell programs to use only evaluation) This kind of evaluations(except Comet) make me wonder if programmers think before writing the piece square tables because I expect more than one pawn bonus for king safety problems in this case and if you do not consider king safety then I also see positional advantage for black because black has 2 passed pawns when white has only one. Are programmers afraid to have big bonuses of more than 1 pawn in the piece square tables? Uri
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