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Subject: Re: MTD(f)

Author: Chris Welty

Date: 12:04:19 07/27/04

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On July 26, 2004 at 23:28:04, Stuart Cracraft wrote:

>But in this position (Reinfeld Win-at-Chess, position #1) I get millions of
>iterations, no convergence, and a never-ending mtdf() loop.
>
>[D] 2rr3k/pp3pp1/1nnqbN1p/3pN3/2pP4/2P3Q1/PPB4P/R4RK1 w - Qg6 0 32
>
>This is the output deep into the run of the code below.
>
>:
>:
>mtdf iteration=9026 lowerbound=7038 upperbound= 9999999 g = 7038 beta = 7038
>mtdf iteration=9027 lowerbound=7039 upperbound= 9999999 g = 7039 beta = 7039

You're only moving a millipawn per iteration. As Tony Werten pointed out,
fail-soft a/b and widening the search window will help (I'd recommend both).

Once that's working your next problem will be search instabilities, where a
window at +1000 returns +950 and a window at +950 returns +1000. One way to
solve this is by only widening the window rather than doing null-window searches
at each value.

Good luck,

Chris



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