Author: Tony Werten
Date: 02:21:17 07/28/04
Go up one level in this thread
On July 28, 2004 at 01:11:44, Stuart Cracraft wrote: >> >>Play with the granularity of the search. If a pawn is worth 64 centipawns you >>will do far less searches than 1000 centipawns. But then you lose resolution. >>So the trick is to find a happy medium, I would guess. > >Done. I made a pawn 64 centipawns instead of 1000 millipawns. >and got a tree reduction for the 30-position test of about 5.589% >so it's on the outer fringes of what I've read in Schaffer's >writings, there being 5-15% reduction. I wonder what the other >tricks are. I cringe at going to fail-soft and having to give up >PVS/NEGASCOUT. There are still some improvements - Fail soft. It doesn't have to break your pvs-negascout since it works in there too ( but gives less ) It is aimed at reducing the number of bestmove searches. - ETC. I never seen anything coming from it in PVS, but heard it works well in MTD. - Don't resolve bestmove. If after 11 searches, you still have a faillow, you know the bestmove score dropped with >= 2 pawns. Rather than resolving the exact score, you can take the score, set a BESTMOVE_STILL_SUCKS flag and continue searching. The idea is that you will find a better move anyway. If not you can still resolve the bestmove score ( or just go 1 ply deeper anyway) but you're in trouble then anyway. - Search deeper :) Tree size gains aren't static. What gives a 5% at fe 10 ply, will most likely give a 7% on 11 ply and a 10% on 12 ply. Unfortunately not so easy to do. Tony > >Googling around for MTD(f) is remarkably sparse as far as amount of practical >examples are concerned. > >Here are the results. > >MTDF 64 centipawns to a pawn >**** 90% 27/30 25.81 6492995 216433/1/251608 0/0/303344/0/0/0 > >MTDF 1000 millipawns to a pawn >**** 90% 27/30 25.69 6640618 221354/1/258440 0/0/307973/0/0/0 > >PVSNEGASCOUT 1000 millipawns to a pawn >**** 90% 27/30 25.56 6877388 229246/1/269110 0/0/316245/0/0/0 > >Tree size reduced from 6,877,388 nodes to 6,492,995 nodes. > >Stuart
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.