Author: Robert Hyatt
Date: 17:40:01 07/06/98
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On July 06, 1998 at 14:11:03, David Eppstein wrote: >On July 05, 1998 at 14:14:36, Ernst A. Heinz wrote: >>>No, not stupid at all -- just obvious and straightforward. I have used it >>>with good success in "DarkThought" for a long time. :-) > >Straightforward, I agree. Obvious? It took me a year to notice, maybe I am >slow, but how many other similar little tricks does everyone have to rediscover >for himself (or worse not rediscover)? > >I think we really need a good text that will cover all these details. >Bob was talking about doing something like that a while ago; what happened? > >On July 06, 1998 at 13:04:17, Robert Hyatt wrote: >>In Cray Blitz (and in crafty, unless I have broken it) I store mates with a >>"draft" of infinity, because a mate is independent of any draft, and is >*always* correct. > >You might find a mate in fewer moves if you searched longer; there's no >game-theoretic value to doing so (assuming your time management code isn't >stupid) but there is a certain aesthetic value. > >As I said, I looked at crafty and didn't see it, which was what led me to think >someone other than myself might not already know about it. StoreBest() and its >relatives certainly detect whether a score is mate, but only use that to modify >word1; the draft lives in word2 and doesn't seem to be conditional on whether >the score is mate. LookUp also has some mate-score-conditional code, but only >after it's discarded too-shallow positions. So if it isn't in these two places, >where are you hiding this piece of code? Good eyes... where it lives is in the version of StoreBest() and StoreRefutation() that uses multiple probes into a single hash table, rather than the current "Belle" implementation. Not sure why it was removed, probably at the request of someone that insisted on finding shorter mates. Once a mate score hits the hash table in CB or the other Store() code, that's it...
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