Author: Dann Corbit
Date: 11:04:55 04/06/04
Go up one level in this thread
On April 06, 2004 at 05:18:00, Tord Romstad wrote: >On April 05, 2004 at 18:58:57, Andrew Wagner wrote: > >>On April 05, 2004 at 18:42:57, rasjid chan wrote: >> >>>On April 05, 2004 at 15:59:40, Dann Corbit wrote: >>> >>>What fruits! I can't yet digest the apple. >>> >>>On a more serious note, it seems there MAY BE much more in hashing >>>than what I know - UB, LB, EX. I need time to see what all these mean. >> >>UB = Upper bound, LB = Lower bound, EX = exact. >> >>When you store a value in the hash table, sometimes it will not be exact, so you >>store some flag along with it that says what kind of position it is. If you just >>failed high, all you know is that the score is at least X. If if failed low, all >>you know is the score is at most X. And if the score is between alpha and beta, >>it's exact. > >Another option is to store _two_ values in the hash table entries, an >upper bound and a lower bound. You will probably also need to store two >depths, one for each bound. > >This is of course more expensive in terms of space, but it will also give >you a bigger number of hash table cutoffs. Whether it is worth the price >probably depends on the engine. In my engine, two bounds work much better. Boy, do I like that idea!
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