Author: Robert Hyatt
Date: 17:18:23 03/24/04
Go up one level in this thread
On March 24, 2004 at 11:17:48, Fabien Letouzey wrote: >On March 24, 2004 at 10:54:31, Robert Hyatt wrote: > >>On March 24, 2004 at 07:21:04, Fabien Letouzey wrote: >> >>>On March 23, 2004 at 17:17:01, Russell Reagan wrote: >>> >>>>On March 23, 2004 at 16:18:24, Robert Hyatt wrote: >>>> >>>>>Hashing can cause odd things. >>>>> >>>>>For example, you ponder for an abnormally long time and finish (say) a 16 ply >>>>>search. As you searched position X at ply=1 (not depth = 1 but ply =1...) you >>>>>get a "fail low" and store (say) score <= XXX, draft=15. >>>>> >>>>>Your opponent makes a different move and you start over. When you reach >>>>>position X, you get a hash hit and you "fail low" because of it, bit when you >>>>>re-search, you can't use that old fail low hash entry and you are not searching >>>>>deeply enough to see the 16 ply problem with the move, so you get a screwy >>>>>score. >>>>> >>>>>There is no solution to this... except drop hashing... >>>> >>>>To be more precise, you don't have to "drop hashing" completely to avoid this. >>>>For example, you could still use the hash table only for move ordering and avoid >>>>the search instability. Of course, it is less effective then. Pick your poison >>>>:) >>> >>>I do exactly that at PV nodes in Fruit, for exactly that reason. >>>Please stop having exactly the same ideas as I do ;) >>> >>>Fabien. >> >> >>That doesn't solve the problem at all. A non-PV move can have a fail-high >>stored in the table. You fail high on the move then fail low when you can't >>resolve it... > >Sorry I was talking about depth/draft inconsistencies. >I don't use aspiration at all. > >Fabien. So was I. You have only solved the problem along the PV. It _still_ exists along non-PV moves just as I explained... this has nothing to do with aspiration issues...
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