Author: Robert Hyatt
Date: 12:05:15 05/06/04
Go up one level in this thread
On May 06, 2004 at 14:31:08, Gerd Isenberg wrote: >On May 06, 2004 at 11:58:11, Robert Hyatt wrote: > >>On May 06, 2004 at 11:38:44, Dan Honeycutt wrote: >> >>>Yet again I apologize for asking a question which I'm sure has been asked many >>>times before, but could someone explain the difference between a fail-hard and a >>>fail-soft and how does is affect a PVS search? >>> >>>I made the guess that, ie, if (score >= beta) if I return score it's a fail-hard >>>and if I return beta it's a fail-soft. It would seem that what I return doesn't >>>so much matter as what I put in the hash table. If I put in the (possibly) >>>higher value of score then I have a higher lower bound and a greater chance for >>>a hash cut if this position arises again. >>> >>>Thanks in advance. >>>Dan H. >> >>That is backward. But you have the right idea. Fail-hard never returns a value >>outside the initial alpha/beta window. Fail-soft does. > >I often confuse this hard/soft definitions too - i have the wrong mnemonic >trick. Intuitively i found it harder if i jump outside a window ;-) It is just as intuitive as where you store a lower bound but flag the position as an UPPER bound position. Makes sense after a lot of thought, but it still leads to confusion... :)
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