Author: Tony Werten
Date: 01:43:30 01/22/02
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On January 22, 2002 at 00:46:01, Robert Hyatt wrote: >On January 21, 2002 at 10:55:50, Daniel Clausen wrote: > >>Hi >> >>On January 21, 2002 at 10:41:39, Robert Hyatt wrote: >>[snip] >>>1. If you get a fail high at the root on a zero-width window (any move after >>>the first move should be searched with a zero-width window) you can't trust it >>>unless you re-search it with a bigger beta bound and make _sure_ that it doesn't >>>then fail low. Such fail-high (zero window) fail-low (non-zero window) is an >>>artifact of null-move and if you play such a fail high move even if it fails low >>>on the re-search, you will die... >> >>Anyone has a trivial example at hand which demonstrates this behaviour? >> >>Why is it that a fail-high with a zero window can't be trusted but a fail-high >>with a non-zero window can? Is "non-zero window" enough to be trusted? Or does >>it have to be a certain minimum window? I'm sure that as soon as someone posts a >>mini-example which shows this behaviour, even I will understand it. :) >> >>Sargon > > >I don't have an example now as I found this bug several years ago and then >eliminated it as I explained. It is an artifact of mixing null-move with >the null-window PVS search. Did you find it to be related to the size of the window ? That's what I seem to get from some tests. BTW wouldn't that make MTD quite useless ? Tony
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