Author: Sune Fischer
Date: 01:52:35 12/26/01
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On December 25, 2001 at 23:56:56, Robert Hyatt wrote: >On December 25, 2001 at 20:21:49, Sune Fischer wrote: > >>I'm sitting here with an implementation problem, I can think of a few ways to >>solve it, but perhaps there is an even better one. >> >>The problem is I can't always get the best move in a position when searching, I >>need a beta cutoff or an improvement in the alpha value. So it isn't save for me >>to assume there is killer in all recorded hash entries, and if I only >>recordhash() when I _can_ put a killer in, then I miss out on some scores. >> >>So I was wondering what solution you guys have found? >> >>-S. > > >If I understand your question, there are three kinds of positions where you >can store a hash entry. PV entry where the score is _EXACT_. You should >have a best move to store hre. > >LOWER entry which is AKA a fail-high position. A move caused this fail high >and it should be stored in the hash as best. > >UPPER entry which is AKA a fail-low position. There is _no_ best move in this >position. I simply store a 0 for such cases... Yeah that's what I mean, the first thing i do in the AB search (I'm not using PVS yet) is to probe, and if succesful I put the killer into the pv and return with the score. At the end of the search I expect there to be a move in the pv, namely the best move the search could find. What if the entire search is returned from a probe hit, one that did not have a move stored, then the pv is empty! I hasn't happend to me yet because most entries do have a killer, but it could happen I guess. -S.
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