Author: Robert Hyatt
Date: 08:40:51 03/02/06
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On March 02, 2006 at 00:48:59, Dezhi Zhao wrote: >On March 01, 2006 at 15:51:29, Robert Hyatt wrote: >>I increment the fail high count by 100 each time a move fails high. I also >>increment the tried count by 1 at the same time. Any time another move fails >>high, and this move was tried but did not, its tried count gets incremented, >>which lowers the "failed high percentage" significantly... >> >>sort of: >> >>if failed_high(x) >> x.count++ >> x.fh+=100 >> >>if failed_high (y) (later) >> y.count++ >> y.fh+=100 >> if (tried(x)) x.count++ >> >>Hope that makes what I am doing clearer, whether it is good or bad is not >>certain yet... >> >> > > >why not keep it simple?! > >Suppose x is any move we just searched. > >x.count++ >if failed_high(x) > x.fh+=100 That grossly biases the statistic downward. You can either count: (a) times a move was searched anywhere vs the number of times it failed high (that ratio will likely be very high, as fail-highs are not that common) (b) times a move was searched and didn't fail high when another move did, vs the number of times it was searched and did fail high. That seems to be a more useful comparison, because now we can say "something failed high, but not this move..." In case (a) there are plenty of times when all moves fail low, particularly when move ordering is very good. And the count value will be very high, but the fh count will be very low. That would say this is an ok move to reduce. In case (b) if something fails high but this move doesn't, then that is more useful to know how many times that happened vs the cases where this move failed high itself. Intuitively it seems better. Whether it actually is or not has not been tested by me (yet).
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