Author: Chan Rasjid
Date: 02:31:05 03/05/06
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On March 04, 2006 at 20:12:47, Robert Hyatt wrote: >On March 04, 2006 at 18:26:47, Chan Rasjid wrote: > >>This is for an earlier thread somewhere. >> >>It may be piece12-to may be better than from-to for history stuff. >> >>A side may attempt to retain a certain board configuration or a part if it >>strong >>especially near the palace. Then such spaces may be good or bad for certain >>piece-type-color and the from sqaure has no relevance, only the type and color. >> >>Also in endgame, the significant pieces are pawns and kings and the above >>analysis >>may also apply. >> >>The above non-random goodness or badness of squares towards type-color will give >>the history value a bias towards fh/fl and it is this non-random bias that makes >>history useful. >> >>Rasjid > >I tried both and could not get piece-to to out-perform to-from. They were >close, but to-from was always just a bit faster for me. I ran several test >suites, including ecmgcp for testing, plus some non-tactical positions to make >sure they didn't behave differently... > >This probably varies by engine, no doubt... history[from + piece12][to] - can this work? This is only my rough idea, may be complete silliness...and I am busy with my bitboard generation. There is "collision" for from1 + pc12_1 == from2 + pc12_2 when from1 != from2 and pc12_1 != pc12_2.But maybe things may balanced itself out and stiil may be best of the 3 history. With from-to, there is already collision of :- a) B 2 color, Q 2 color, P 1 color b) R 2 color, Q 2 color, P 1 color c) N 2 color, else ok. Maybe a brute run for collision can help, ie using a brute loop of [from+pc12][to] to flick out the collision characteristic, etc.. to see if they are a problem. Or maybe adding a suitable constant K to [from + pc12][to + K] may do the trick. Rasjid
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