Author: José Carlos
Date: 05:55:56 11/03/03
Go up one level in this thread
On November 02, 2003 at 15:26:06, Christophe Theron wrote: >On November 02, 2003 at 05:38:58, Kurt Utzinger wrote: > >>On November 02, 2003 at 04:54:06, Gian-Carlo Pascutto wrote: >> >>>On November 02, 2003 at 03:44:09, Ricardo Gibert wrote: >>> >>>>On November 02, 2003 at 03:20:26, Kurt Utzinger wrote: >>>> >>>>>A good example where Chess Tiger 15 needs much more time than >>>>>most other engines to evaluate the position as a draw: >>>>> >>>>>[D]8/8/r7/3K4/3Q4/5p2/5p2/6k1 b - - 0 1 >>>>> >>>> >>>>This is also a good example of a type of position of negligible practical >value. >>>>I don't think CT15's programmer needs to worry about it at all. >>> >>>*cough* *cough* *cough* >>> >>>IsiChess - ChessTiger, Dutch Open 2003 >>> >>>-- >>>GCP >> >>IsiChess MMX - Chess Tiger >>[D]8/1k6/p5q1/4P3/1P3P2/7Q/3K3p/8 b - - 0 1 >> >>Analysis by Chess Tiger 15.0: (P4 1.8/24 MB hash) >> >>64...Qg1 65.e6 Qd4+ 66.Kc1 Qa1+ 67.Kd2 >> µ (-0.88) Depth: 1 00:00:00 >> -+ (-7.51) Depth: 4 00:00:00 2kN >>64...Qb1 65.Qd7+ Kb6 66.Qd6+ Kb5 67.Qc5+ Ka4 68.e6 Qf1 >> -+ (-7.80) Depth: 4 00:00:00 5kN >> -+ (-7.41) Depth: 6 00:00:00 15kN >>64...Qg1 65.Qd7+ Kb6 66.Qd8+ Kb5 67.Qa5+ Kc4 68.Qxa6+ Kxb4 69.Qb7+ Kc5 70.Qa7+ >>Kc4 71.Qa4+ Kd5 72.Qa8+ Ke6 >> -+ (-8.02) Depth: 6 00:00:00 47kN >> -+ (-7.80) Depth: 15 00:02:16 55491kN, tb=187 >> >>(Utzinger, MyTown 02.11.2003) >> >> >>IsiChess MMX - Chess Tiger >>8/1k6/p5q1/4P3/1P3P2/7Q/3K3p/8 b - - 0 1 >> >>Analysis by Deep Sjeng 1.5: >>*************************** >> >>64...Qg1 65.Qd7+ Kb6 66.Qd8+ Kc6 67.Qd6+ Kb5 68.Qb8+ Kc6 >> ² (0.40) Depth: 3/12 00:00:00 >> = (0.21) Depth: 5/18 00:00:00 >>64...Qf7 65.Kc3 Qxf4 66.Qd7+ Kb8 67.Qd8+ Ka7 68.Qd7+ Ka8 69.Qc6+ Kb8 70.Qe8+ Ka7 >>71.Qd7+ >> = (0.06) Depth: 5/19 00:00:00 >> = (0.00) Depth: 9/29 00:00:05 1986kN, tb=162 >>64...Qg1 65.Qd7+ Kb6 66.Qd8+ Kb5 67.Qa5+ Kc6 68.Qxa6+ Kd5 69.Qb7+ Ke6 70.Qc8+ >>Kd5 71.Qb7+ Ke6 72.Qc8+ Kd5 73.Qb7+ >> ³ (-0.48) Depth: 9/29 00:00:07 2593kN, tb=163 >> = (0.00) Depth: 13/38 00:00:49 17560kN, tb=1597 >> >>(Utzinger, MyTown 02.11.2003) > > > >It's the problem when you allow a huge speculative evaluation of passed pawns. >You have to add an almost infinite number of exceptions if you want to handle >this perfectly. > >And I don't think it is possible to program even this exception. I'm pretty sure >you could, by moving just one pawn, turn this position from a draw to a win. > >On the other hand, when I tried to add a speculative evaluation of perpetuals I >got worse results. Yes it would look smarter in positions like this one, but the >winning rate dropped. > >Which probably only means that I did not do it right. > >In the same vein, the following position has always been a nightmare for Tiger: > >[D]8/1KP5/3q2k1/8/6p1/8/8/8 b - - > >This position comes from a real game between the Modular Game System Sargon 2.5 >and Mike III, played in September 1980 during the Personal Computer World Fair. >Mike III continued the game with a long series of checks leading to a draw. > >Chess Tiger is not smarter than Mike III here. It is something that I had fixed >in the 16 bits version, to the expense of some added complexity in the passed >pawns evaluation code. I have not transfered this code to the 32 bits version >because it was not general enough (add another black pawn and the code did not >work). > >I am interested in results of other (amateur and commercial) programs. > > > > Christophe Anubis 0.00.0030 PIII - 933 30Mb hash 4 9.99 0.13 2458 d6b4 b7c8 b4f8 c8d7 f8g7 d7d8 g7h8 d8e7 5 9.99 0.18 5877 d6b4 b7c8 b4f8 c8d7 f8g7 d7d8 g7h8 d8e7 h8f6 e7d7 5 10.98 0.24 20232 d6c7 b7a8 c7d8 a8b7 g4g3 b7a7 g3g2 6 104.28 0.28 22418 d6c7 b7c7 g4g3 c7b8 g3g2 b8a8 g2g1Q 7 106.20 0.42 68874 d6c7 b7a6 g4g3 a6b5 g3g2 b5a4 c7c4 a4a3 c4b3 a3b3 g2g1Q The trick is very easy in this case: I have a special function to evaluate KQK. The first line is: SINT32 s32Eval = pPos->s32EvalMaterial * 10; After that, I add / substract bonus for the normal things we evaluate there (king proximity to the edge, etc...) I hope this helps Tiger somehow... ;) José C.
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.