Author: Antonio Dieguez
Date: 20:28:31 02/15/03
Go up one level in this thread
On February 15, 2003 at 22:32:41, Robert Hyatt wrote: >On February 14, 2003 at 13:19:37, Antonio Dieguez wrote: > >>On February 14, 2003 at 11:33:12, Robert Hyatt wrote: >> >>>On February 14, 2003 at 00:51:54, Antonio Dieguez wrote: >>> >>>> >>>>>All that is critical is that you store the same depth you probe with. If you >>>>>do some extensions before storing, you had better do those same extensions >>>>>before probing. IE if you don't, you are going to introduce some huge artifacts >>>>>that will break things. >>>> >>>>It seems that is not all what is critical because precisely you may don't know >>>>if the same extensions will happen in both ocassions. >>> >>> >>>That is dangerous. The hash table stores a "position" and a "value". If >>>the "position" is different, then the value is useless. If you apply different >>>extensions in the _same_ position, then how can you possibly use a hash table >>>hit, since you won't know which "case" it should really be matching. >> >>Anyone who relies on alpha or beta to decide an extension is doing that already. >> >>>The usual (and correct) way of hashing is to probe in the search, _before_ >>>you do any extensions or anything at this specific ply. And when you store, >>>you store the _same_ depth you had when you entered search and did the probe >>>that failed, so that the next time you probe, and get a match, it makes sense >>>to use it. >> >>Probing before checking for extensions make less sense in the case I mentioned >>above. >> >>>Any other approach is going to produce instabilities. >> >>I don't think so, especially if there are prunning depending on beta or alpha, >>probe and store after making the extension is correct. And the only way wich >>could introduce more instability (depending on the program) is probing and >>storing with the original depth. >> > > >If you read my comment, the main point was that it must be _consistent_. _Obviously_... it must be consistent, but your words were the ones that looked to me not consistent. > I probe before extensions, and store the same way. If you probe and store >after extensions, there is nothing wrong with that since it is _consistent_. >But with extensions based on alpha/beta values, this will wreck things. Yes, it will wreck things for the way of doing things you most recommended. But we agree so all is ok.
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