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Subject: Re: late move reductions

Author: Robert Hyatt

Date: 13:25:08 03/01/06

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On March 01, 2006 at 16:13:47, Frank Phillips wrote:

>Thanks for sharing this.  I am at the preliminary stages and just thinking about
>refinements.  Initial indications are:
>1. Basic implementation, not if move extended or check or threat..etc, improved
>scores on tactical tests.
>2. Crude use of history scores helped again  In this simple case calculating the
>max. history score after each root move and only reducing if move history < 50%
>(say).  (My history scores are not 2^depth and therefore do not grow ultra
>fast.).

I haven't used 2^depth since the early history testing back in 1995 when I first
started with Crafty.  I have been using depth*depth to keep counters from
overflowing too quickly and corrupting history values...

>3. Next stage was thoughts about trying explicit counters of when moves
>fail/not_fail high rather than using the history score, or adding piece_type to
>the history counters, which you just mentioned below :-)

The counters are better for me.  So far, after just testing WAC with my usual
scheme that says "terminate a position after completing the first iteration
where the key move is found") has suggested 50% as the best result there.  I am
now doing the same test on ecmgcp, 20 seconds per position but terminating as
soon as the key move is found, and I am trying history % values from 10 through
90 by 10's for starters...




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