Author: Christophe Theron
Date: 08:58:18 11/05/03
Go up one level in this thread
On November 05, 2003 at 03:03:19, Tony Werten wrote:
>On November 04, 2003 at 13:58:29, Christophe Theron wrote:
>
>>On November 04, 2003 at 02:43:34, Tony Werten wrote:
>>
>>>On November 03, 2003 at 13:22:42, Christophe Theron wrote:
>>>
>>>>On November 03, 2003 at 10:04:32, Will Singleton wrote:
>>>>
>>>>>On November 03, 2003 at 02:35:09, Gerd Isenberg wrote:
>>>>>
>>>>>>On November 03, 2003 at 02:33:02, Gerd Isenberg wrote:
>>>>>>
>>>>>>>On November 02, 2003 at 17:12:38, Will Singleton wrote:
>>>>>>>
>>>>>>>>On November 02, 2003 at 16:52:49, Gerd Isenberg wrote:
>>>>>>>>
>>>>>>>>><snip>
>>>>>>>>>>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
>>>>>>>>>
>>>>>>>>>Hi Christophe,
>>>>>>>>>
>>>>>>>>>IsiChess on AMD XP2.6+ first shuffles around with Qb4+, Qxc7 and Qd7.
>>>>>>>>>After 5 seconds at depth 13 Qxc7 came up. Mate in 14 resp. 12 after one minute
>>>>>>>>>and 1:10. I guess a matter of won KPK eval.
>>>>>>>>>
>>>>>>>>>Cheers,
>>>>>>>>>Gerd
>>>>>>>>
>>>>>>>>Sure, but I'm not sure CT was referring to finding the mate as the problem. CT
>>>>>>>>seems to have some problem understanding that KQK is better than KQKP, that's
>>>>>>>>all I can figure.
>>>>>>>>
>>>>>>>>Will
>>>>>>>
>>>>>>you mean won KPK against KQPKP? I use interior node recognizers and assign
>>>>>>shlightly more than queen advantage in won KPK. Additionaly there is a
>>>>>>heuristic, that reduces score a bit (e.g. abs(delta material) / X) if a lot of
>>>>>>checks occur with "no progress".
>>>>>> ^^^^
>>>>>>Gerd
>>>>>
>>>>>I do that too, but it's constrained to several consecutive checks that don't
>>>>>reset the fifty-move counter. Seems to help in some positions, but I'm not sure
>>>>>how generally effective it is.
>>>>>
>>>>>Will
>>>>
>>>>
>>>>
>>>>That's exactly what I have tried, with different values for X and the number of
>>>>consecutive checks needed to trigger it.
>>>>
>>>>It has always weakened my program. Not by much, but I expected a minor gain, not
>>>>a minor loss!
>>>
>>>Make sure your trigger is counted from the back, not the front. ( I don't want
>>>to make it too easy :)
>>>
>>>Tony
>>
>>
>>
>>I really don't understand what you mean...
>
>Whatever adjustments you do after no progress, it is only important if the last
>fe 5 moves made no progress (or gave checks). If the first 5 moves did this and
>then there is a no-check or capture you should do nothing.
>
>If you trigger from the front (ie root) you'll seriously weaken the engine
>because sometimes it is nescessairy to shuffle some pieces around before doing
>something, but you will be giving a penalty for that.
>
>Tony
Oh yes. That's how I did it. When I reach a leaf I check if the last X plies
where just checks without capture (X=10..12).
Probably my definition of "no progress" was not restrictive enough. For example
if there is a pawn push, it is not a case of "no progress" I guess.
Christophe
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