Author: Andrew Williams
Date: 02:53:47 10/28/99
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On October 27, 1999 at 17:08:40, Scott Gasch wrote:
>[...]
>>int simplePP[8] = { 999, 55, 33, 23, 16, 12, 0, 0 };
>[...]
>
>This is interesting... a pawn on the seventh for cyclone is 255 (+2.55) while on
>the 6th rank is 128. It also gets a passed pawn bonus of 30 unless it is
>blocked in which case it is 15. King support is 20. Connected passed pawns get
>+3 each additional.
>
>The reason that I used 255 as the 7th rank static bonus is because the engine
>was so cavalier about playing passed pawns until I upped this drastically. A
>good percentage of its losses were due to ignoring a passer and doing other
>stuff until it got to the 6th or 7th rank. It was not until then that the
>program realized it was in trouble.
>
>I justify the 255 score because even an unpromotable but sustainable passed on
>the seventh is tying up at least one minor piece. This is often a winning
>advantage for the side with the pawn threat.
>
>Comments?
>Scott
I've found that with very high scores for passed pawns on 6th/7th, my program
manages to force a PP up there during the middlegame, but with most pieces
still on the board it gets surrounded and captured, leaving my program with
whatever positional weaknesses it had to concede to get the Pawn there in the
first place. I prefer to rely on my other features to tell me if the Pawn
deserves a mega-bonus or not.
Passed pawn evaluation is tough. Apart from King Safety, this is the part of my
evaluation that has had most work.
Andrew
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