Author: José Carlos
Date: 23:46:54 12/13/00
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On December 13, 2000 at 20:45:14, Scott Gasch wrote: >Hi, > >I had an idea recently about improving the ordering of non-captures. Up until >now I have been using a history heuristic (with 2 killers). > >The idea is to try non-captures that threaton the last piece moved, flee from >the last moved piece, or whose "footprint" overlaps the footprint of the last >move before their peers. By footprint I mean the set of squares a piece of type >T in square X can move to if nothing else is on the board. > >Doing some tests on different positions I decided to throw away the "flees" >case... I am skeptical of its soundness and it always grew the tree... >sometimes quite severly. > >The other two (overlapping footprints and attacks the last moved piece) both >grow the tree anywhere from slightly to greatly. I tried different bonus >weights, bonus + history and bonus alone, etc... and the best I ever got was >trees of equal size in _some_ positions. > >Despite this fact I still think there might be some merit in this idea. Surely >its better for move ordering to try, for example, threatoning pawn pushes before >quiet ones or moving a to support a square attacked by the opponent's last move >before moving randomly... My question to you guys is if anyone else is doing >anything similar and what have your results been like? > >Thanks, >Scott In Averno, I do something not related to this but interesting too, IMO. I use piece-square tables to diferentiate moves with the same order precedence. For example, all bishop moves have equal precedence plus a number depending on the target square. This is in Averno from the begining. Some time ago, I decided it was slowing the search, so I removed it. The tree grew, so I decided to leave it there. José C.
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