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Subject: Re: Couple of chess programming questions

Author: Sven Reichard

Date: 13:35:24 09/10/02

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On September 10, 2002 at 15:48:40, Vincent Diepeveen wrote:

>
>perhaps it is good to clarify one thing. As soon as a MTD search
>needs to use a binary form of search to get from value A to B, then
>mtd will fail of course.
>
>the advantage of mtd is that if you have a bound search at 0.01 which says:
>"it's more than 0.01" then you try 0.02. In this way you need only a
>few minimal windows to get from 0.01 to 0.03
>
>The statement of Rudolf is very clearly: "such minimal windows are
>very cheap", and looking to SOS i can only agree with him.
>
>A major problem is like bob says if you have a 0.3 difference.
>even with pawn = 100 and 0.3 being 30, that means you need 30 researches.
>

This is a worst case scenario. The MDT(f) algorithm uses a fail-soft test, so
usually if you call it with a bound  of, say, 0.01, it doesn't tell you it's
greater than 0.01, but rather "it's at least 0.08". This saves you on average
quite a few steps.

For me it didn't work since MDT(f) introduced tactical errors. Still trying to
figure it out, but I suspect it's the combination of minimal windows with
agressive null-move pruning.

Sven.



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