Author: Jeremiah Penery
Date: 01:27:03 12/01/99
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On December 01, 1999 at 02:50:01, Inmann Werner wrote: >On November 30, 1999 at 20:04:00, Gerrit Reubold wrote: > >>Two Months (?) ago we had a thread "what should we store if all moves fails >>low?" with the answer: Nothing! There should be a saving of a few percent of >>treesize if you don't store "random" moves in the HT. Maybe this could be an >>improvement of your algorithm? >Why stuff in nothing at fail low? >fail low is bad for move ordering, so I do not use it there. Ok. >But for normal hashing, I use fail low, if the value<alpha. At mate values, I >give back something like mate in 500....(brings my prog to sometimes not show >right "mate in #", bothers me not much) >I overwrite fail low values first, cause they are the "less value" entrys. >Why should I search all moves, only to recognize, that it again is a fail low? >I see nothing good in it. The idea is that when you have a fail-high node, ALL of the next-ply moves have failed low. In this case, you should store nothing in the hash table, because you don't have a good move to store. If you do store a move here, it's as good as storing a random move, because any of those moves can turn out to be the WORST move. They all failed low, and here the algorithm will not tell us which one is the best; they must be re-searched. Storing a move here will hurt move ordering, because you keep getting hash-table hits that tell you to search this move first, even if it turns out to be the worst move.
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