Author: Stefano Gemma
Date: 07:53:16 05/26/04
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On May 25, 2004 at 07:59:33, Tord Romstad wrote: >In all implementations of iterative deepening I have seen, the search depth >is always incremented by exactly one ply between each iteration. Is there any >reason to believe that this is optimal? Has anybody tried other increments? > >I am now running some tests with an increment of 3/4 of a ply. So far, the >results don't seem very different from the usual 1 ply increment. If it turns >out that increments different from 1 ply are no worse, this could perhaps be >useful in time management. The engine could use 1 ply increments most of the >time, but occasionally add only half a ply if just a small amount of the >allocated thinking time is left. >Any thoughts about this? I've used an recursive-iterative deepening. I try to explain in my poor english. At any N plyes i've applyed iterative deepening as for the root. Suppose to start with 2 plies. The next iterations you should search 4 then 6 then 8 plies etc, form the root. But, when you're searching 8 plies depth, and you are at a position located at ply 2, why don't use iterative deepening starting from ply 2, instead to do a full search of the remaining 6 plies? So i've tried to consider positions at ply 2 (and 4 and 6...) as they were at the root, and start a search to ply 4, then 6, then 8. Sometimes works better, sometimes worse... I have tried different schemas, in Raffaela. The best seems the schema 2-4. You increment the iterative deepening by 2 plies (one chess move by colour) and, for any ply, you make an iterative deepening with increment 4. In some position, 2-2 was better. I've abandoned this idea, for now, because i'm working on a new engine and i've little time for my hobby, but i think that could be interesting. Ciao!!! Stefano Gemma
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