Author: Robert Hyatt
Date: 13:18:24 03/23/04
Go up one level in this thread
On March 23, 2004 at 09:43:31, Jaime Benito de Valle Ruiz wrote: >If you're using a small aspiration window at the root, and it fails low (this is >a score below the lower window value, right?), is there any chance that the REAL >score is actually above the window value? If this is possible, could you give me >an example? >Thank you, > > Jaime 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...
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