Author: Uri Blass
Date: 22:28:23 12/28/05
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On December 28, 2005 at 18:58:57, Robert Hyatt wrote: >On December 28, 2005 at 12:46:30, Tord Romstad wrote: > >>On December 28, 2005 at 12:31:13, Stuart Cracraft wrote: >> >>>Hi - I ran a small experiment last night. >>> >>>Many people don't put mobility into their evaluation function because of the >>>heavy expense of a move-gen at the terminal node. >> >>I am fairly sure almost everybody uses some kind of mobility in their >>evaluation function. The only exception I know among reasonably strong >>programs is Crafty (I am not quite sure, though -- I haven't looked at >>Crafty recently). > >yes and no. Crafty does some mobility. bishops have a normal mobility term, >for example, but with rotated bitboards, the cost is almost nothing. The first >eval I wrote was 100% mobility. But many things are commonly used to replace >mobility with an indirect form. Rooks on open files for example. Increases >mobility, but that mobility is better than a rook that attacks more squares,but >in a limited way. You can do combination of this and give bonus for rook on open file but also give bonus for rook that attack more squares. Fruit for example does it. I don't do any sort of knight mobility, and once even did >queen mobility although I do not today. fruit does both knight mobility and queen mobility but consider knight mobility as more important. Too much queen mobility in the opening can lead to developing the queen and this is the reason that it evaluate queen mobility as more important in the endgame. > >There are _lots_ of ways to get to mobility without actually doing mobility. >"knight on the rim is dim" is a measure of mobility, or the lack thereof, for >example. Not enough because you do not have difference between knight that is blocked by friendly pieces and knight that can move. Uri
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