Author: Tord Romstad
Date: 02:25:55 12/29/05
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On December 28, 2005 at 18:39:28, Dann Corbit wrote: >I would test it in your eval for benefit. Tord does not calculate queen >mobility, for instance. This is incorrect. I do use queen mobility, in Glaurung Mainz as well as in the most recent development versions. You probably misunderstood a post of mine in a different sub-thread, where I wrote that I haven't been able to measure any difference in strength when I switch queen mobility on or off. Because queen mobility doesn't seem to hurt, I have chosen to leave it enabled. By the way, I would be interested in learning how to compute the kind of mobility I use in Glaurung by using bitboards. I haven't found anything faster than counting the non-zero bits of a bitboard, which is actually slower than my current code. 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. Tord
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