Computer Chess Club Archives


Search

Terms

Messages

Subject: Re: piece mobility?

Author: Zach Wegner

Date: 07:53:41 01/08/04

Go up one level in this thread


On January 08, 2004 at 08:49:27, Russell Reagan wrote:

>On January 08, 2004 at 08:28:25, Daniel Shawul wrote:
>
>>Hi
>>
>>I don't do piece mobility eval in my chess
>>engine.Have heard Ruffian 2 uses intensive piece mobility eval and
>>I would like to do it in my engine.At the moment,mobility is done only for
>>bishops in my engine.
>>I count the possible moves(costy for me,i use bitboards) and assign some value
>>accordingly.
>>I don't do it for other pieces because haven't seen/understood its importance
>>yet.A web page on mobility eval is appreciated.
>>
>>regards
>>daniel
>
>If you use rotated bitboards you can compute mobility for the same cost as
>producing the bishop attack bitboards. Instead of your lookup table returning an
>attack bitboard, have it return the number of attacks. I remember seeing
>something like this in Crafty, so take a look there.

A better way would be to have a weighted square value that you can calculate for
free in the initialization. You know the square of the piece and which squares
it attacks, so why not? If it is just a popcount, then you can have a mobility
table for all sliding pieces in all directions in one 8*256 array, rather than 4
64*256 tables.



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.