Author: Uri Blass
Date: 08:21:28 12/29/05
Go up one level in this thread
On December 29, 2005 at 10:05:07, Tord Romstad wrote: >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 In this case you are right but I can also think about cases when some piece is pinned and it is worse than a pawn that is pinned. a blocked pawn that reduce mobility is a problem but if the pawn that reduce mobility is not blocked then it may move in the next move. compare the following positions. pawn that is pinned and reduce mobility is no problem. rook that is pinned and reduce mobility is a problem. [D]5rqk/5ppp/8/7b/8/5R2/2B2PPP/3Q2K1 w - - 0 1 [D]5rqk/5ppp/8/7b/8/5P2/2B2PRP/3Q2K1 w - - 0 1 Uri
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.