Author: Fabien Letouzey
Date: 08:17:48 03/24/04
Go up one level in this thread
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.
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