Author: Tord Romstad
Date: 07:05:07 12/29/05
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On December 29, 2005 at 05:51:48, Uri Blass wrote: >On December 29, 2005 at 05:25:55, Tord Romstad wrote: > >>For each piece on the board (except pawns and kings), I look at all >>squares this piece attacks, and divides them into three classes: >> >>a) Empty squares and squares occupied by enemy pawns or pieces. >>b) Squares occupied by friendly pieces >>c) Squares occupied by friendly pawns >> >>I then compute the mobility bonus for the piece by a table lookup: >> >>mobility[side] += >> BishopMobilityBonus[(squares of type a) - (squares of type c)]; >> >>In other words, I use a negative mobility increment for attacking >>squares occupied by friendly pawns. > >Did you do some tests that supported the theory that this negative mobility help >relative to no negative mobility? Not any very systematic testing. I tried several different mobility schemes (I don't remember the details), and kept the first one which seemed to be a clear improvement. It is certainly possible that it could be improved further. >I never thought to do negative mobility like that and I doubt if it is good. >Intuition does not tell me that it is going to help. My intuition is different. When a piece is blocked by a friendly pawn, it is usually more serious than when it is blocked by a friendly piece. Pawns are more difficult to move, especially without introducing weaknesses. Consider the following two positions: [D]6k1/5ppp/4p3/3pP3/3P4/6B1/5PPP/6K1 w - - 0 1 [D]6k1/5ppp/4p3/3pN3/3P4/6B1/5PPP/6K1 w - - 0 1 I think it makes sense to give the bishop a bigger mobility bonus in the second position than in the first. Tord
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