Author: Robert Hyatt
Date: 08:29:40 10/29/02
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On October 28, 2002 at 19:39:15, Nagendra Singh Tomar wrote: >I am using iterative deepening with transposition tables. Suppose at some >point in the match I have a board that is say stored in hash with stored depth >10. So when iterative deepening searches that position with increasing depth, >till depth 10 hash_probe will return the stored position and so alphabeta >returns instantly. Since I am not using some hash2pv kind of function, I get a >PV length of 1 with the best hash move being on the PV. But now when the >iterative deepening searches for depth 11, the (stored_depth>= depth) clause >is not true inside hash_probe and hence it does not return the stored >position. Just because the draft was insufficient to let you take the score as good and produce a cutoff, you _still_ use the hash move as the first move to search at this ply... >Now alphabeta is on its own with no PV to help it order the moves >(just some help from the hash inmove ordering). In such cases my program takes >an unusually *long* time to search the next iteration (11th in this example). >This reminds me of the days when I was not using iterative deepening and >searching to a fixed depth. >Is this normal behaviour, or dies it say something about the inefficiency of >the hash ? >What do we do to avoid this ? > >regds >tomar
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