Author: Andrew Williams
Date: 03:42:07 10/27/99
Go up one level in this thread
On October 27, 1999 at 06:34:24, James Robertson wrote:
>On October 27, 1999 at 06:25:31, Andrew Williams wrote:
>
>>On October 27, 1999 at 02:59:52, James Robertson wrote:
>>
>>>I'm trying to write some code to evaluate passed pawns. Specifically, I want to
>>>know how people score pawns as they advance toward the 8th rank. How much bonus
>>>do you give each square the pawn advances? Does this increase with connected
>>>passers? I think Bob mentioned that if the King is defending the pawn or it is
>>>blocked by an enemy piece certian bonuses/penalties are given. What do other
>>>people do about this?
>>>
>>>Any help is appreciated. If I can get my program's passed pawn code in before
>>>Thursday when I leave for the Dutch Open, I will be very happy. :)
>>>
>>>James
>>
>>James,
>>
>>PostModernist considers:
>>
>>How far away from promotion is the pawn?
>>
>>Is the Pawn unblocked?
>>
>>Is the Pawn touching another friendly passer?
>>
>>Is there another friendly passer on an adjacent file (but not touching)?
>>
>>Is it an outside Pawn with very low enemy material? (This is very
>>unsophisticated at the moment in PM)
>>
>>Is it guaranteed to promote in a KPK endgame? (Rather crude, but reasonably
>>effective).
>>
>>A long time ago, I got PM to analyze thousands of games (TWIC?) to give me some
>>idea what these scores should be. Basically, I went through these games, looking
>>for a Passed Pawn. I then "evaluated" the PP, deciding which of PM's factors
>>matched the Pawn. By considering whether the game ended in a win, draw or loss
>>I generated probabilities, which I converted into scores for each factor. I fed
>>these scores into my program but they were no better than simply picking scores
>>and tuning them. The approach didn't work well I think, because in GM games, if
>>a decisive passed pawn is going to score, it rarely reaches even the seventh
>>rank; the GMs both see the outcome many moves before and the loser resigns. I
>>guess that apart from time-trouble cases, you generally see passers on the 7th
>>only if both sides have them and both will promote. I didn't factor that into
>>the assessment I was doing. Still, it was an interesting experiment.
>>
>>I've since changed my PP eval considerably, so the factors I now use are
>>somewhat different to then.
>>
>>Andrew
>
>About what score do you give a pawn on the 7th just for being there? How about
>the 6th? I am trying to find some flat values just to give advanced passed
>pawns.
>
>James
I meant to say, there's a minimum for any passed pawn, which is given here.
The array below is based on distance from promotion. The first value is
meaningless of course.
int simplePP[8] = { 999, 55, 33, 23, 16, 12, 0, 0 };
Andrew
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