Author: Uri Blass
Date: 22:53:53 01/21/02
Go up one level in this thread
On January 22, 2002 at 00:44:53, Robert Hyatt wrote: >On January 21, 2002 at 14:27:34, David Rasmussen wrote: > >>On January 21, 2002 at 10:41:39, Robert Hyatt wrote: >> >>> >>>You have to do two things: >>> >>>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... >>> >> >>If you mean, do I count value >= alpha+1 from zero-window search as a fail high, >>then no. In that case, I research with the original alpha;beta window. Isn't >>that ok? >> > > >What if you run out of time? You failed high on the null-window search. >You started a new search with a wider window and time expired. Do you play >the fail-high move or stick with the previous best move? I stick with the >last verified move. > >Unless I fail high a second time which means the original aspiration window >was too small and I am now going to +infinity. I trust the second fail high >but not the first. Does it mean that even if the evaluation before the fail high was mate against youself you are not going to play the fail high move if you have not time to verify it? In this case it is a mistake. It seems better to have a rule based on the previous evaluation when to play the fail high move that you cannot trust and when not to play it and not to play it only when the evaluation is bigger than some number. I have no idea about the exact number and looking at positions when Crafty did not play a move that fail high may help to get a better idea. Uri
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