Author: William Penn
Date: 04:40:04 03/03/04
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I believe another reason why the first moves calculated at a particular ply level take longer is transpositions. Each move is a transposition with every other possible move at that ply level. After you calculate a move it's placed in the hash table (presumably) so it doesn't have to be calculated again. Then you proceed to the next move in the list, and it can look up its transposition with prior moves - so doesn't have to recalculate them. By the time you get past the halfway point in the list of possible moves, transpositions have already calculated with more than half of the possibilities, so things tend to speed up considerably. When you get to the last move in the list, transpositions with all prior moves have already been calculated. This process is seriously interrupted (takes a long time) if a better first move is found along the way, so that all transpositions have to be recalculated before it can assume top spot on the list (or something similar). I'm not sure if all engines work in this manner. I believe Fritz & Shredder probably do, but Junior's limited info output makes it difficult to say. WP
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