Author: Christophe Theron
Date: 10:24:05 11/03/03
Go up one level in this thread
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?
Christophe
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