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Subject: Re: MTD(f)

Author: Stuart Cracraft

Date: 22:11:44 07/27/04

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>
>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.

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





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