Author: Fabien Letouzey
Date: 04:21:04 03/24/04
Go up one level in this thread
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.
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