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Subject: Re: MTD concept and why PVS is superior

Author: Bo Persson

Date: 13:11:50 06/21/05

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On June 20, 2005 at 08:06:08, Vincent Diepeveen wrote:

>
>If at 13 ply the score of other moves is 0.35 or so and from this root move it's
>0.400, then we have a 100 point difference between 0.300 and 0.400.
>
>Now we need possibly a 100 researches to get to 0.400, but at least 2 dozen or
>so. As we will use bounds 0.300 0.301 0.302 0.303 0.304, hoping that the score
>is close to 0.300 of iteration 12 of course.
>
>PVS is far superior in this as we can determine the true bound directly by
>taking the tree of 12 ply search depth. We add 1 ply to it and we already have a
>root score of real close to 0.400 to it. So for the price of a node or 50 using
>hashtables we directly determine a true bound or somethign real close to the
>true bound, where MTD needs 20+ researches for.
>
>Is my point clear now?

This is the usual Vincent thing - he can't get it to work, so it just doesn't
work.

Who said you had to add 1 millipawn for each research? You can accellerate the
step (+16, +32, +64, etc), until you step over the target, and then zoom in
again.

To go from 0.300 to 0.400, my program tries this series:

0.300 0.316 0.348 0.412 (fail low!) 0.380 0.396 0.404 0.400

That's eight (8) searches, not 100, not even 20+ !


Bo Persson

>
>Vincent
>



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