Author: Robert Hyatt
Date: 09:27:31 02/09/04
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On February 09, 2004 at 00:58:01, Angrim wrote: >On February 08, 2004 at 11:46:28, Robert Hyatt wrote: > >>On February 08, 2004 at 00:19:28, Pham Hong Nguyen wrote: >> >>No. I used to do this. But what can happen is that your search can slow to a >>few hundred nodes per second. If you can't see how to win with the reduced >>depth, it is likely you will stumble into "how to lose" because the depth will >>be so limited, you can get killed tactically.. > >How about a compromise where you probe only the 3 and 4 piece tables >in the qsearch, since they should all be cached in ram. > >Angrim There is a danger. You then mix perfect information with non-perfect information. And inconsistent behavior is the result. IE if I probe everything up to the q-search, but then only probe 3-4 piece tables, it is more than possible that I pass over a drawn 5-piece ending, to reach a 4-piece ending I am winning or losing. Comparing the scores then becomes a problem and alpha/beta doesn't like doing that very well. It is bad enough to have some artificial boundary beyond which you don't probe, as that allows for the classic horizon effect where you push a capture off to beyond where you see that it loses or draws according to the table, then you can make your plans accordingly, only to realize in a couple of moves that you are committed to a path that you thought was winning, but isn't. Adding another discontinuity only increases the chance that such horizon effects happen.
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