Computer Chess Club Archives




Subject: Re: MTD(F) results

Author: Dann Corbit

Date: 18:53:59 12/16/03

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On December 16, 2003 at 21:22:56, Anthony Cozzie wrote:

>Recently I experimented with adding MTD(F) into Zappa.  It has been an
>interesting experiment, but I am going back to PVS().
>I thought that since Zappa has a [UL,LL] paired transposition table and an
>evaluation granularity of only 1/100 of a pawn, MTD(f) would work quite well,
>but that does not seem to be the case.  The MTD(f) version of Zappa does
>slightly better on test suites (113/183 @ecmgcp v 106 @ 10s/move) but in the
>positional test suites it averaged about 3/4 of a ply less than the PVS()
>version.  My guess is that because MTD(F) tries all moves, some of the
>"ridiculously losing captures" ordered near the end by PVS() are tried earlier,
>which accounts for the increased test suite performance.
>If anyone has any suggestions, I'm keeping the MTD(F) code in Zappa (just turned
>off) and I'm willing to try anything.

Here is an interesting experiment:
Try searching with a granularity of 1/10 of a pawn instead of 1/100 for all
moves except the pv.

The number of searches in MTD(f) is essentially the log of the resolution in
bits of the search window.

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