Author: Tony Werten
Date: 23:36:47 11/03/03
Go up one level in this thread
On November 03, 2003 at 13:24:05, Christophe Theron wrote: >On November 03, 2003 at 02:00:46, Tony Werten wrote: > >>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. >> >>XiniX only shows moves from ply 5. It is already on Qxc7 then. It changes at ply >>9-11 to Qd5 ( and after Ka7 Wc5+ Kb8 Kf5 c8Q+ it will capture on c8, same idea ) >>and then changes back to Qxc7. >> >>XiniX does have special perpetual check code. >> >>All tablebases disabled of coarse. >> >>Tony > > > >Are you sure that your perpetual check code makes the program really stronger? Nope, but at least it doesn't seem to weaken it anymore. It's combined with a no progress part, wich might be more important here. Going from KQPkp to KQk is seen as a very big progress. The checking part seems works well in my program, but that probably also has to do with giving checks in quiescence. In most cases, it does get the chance to prove it's not perpetual, only if it can't prove that, the threat is taken seriously. Tony > > > > Christophe
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