Author: Bert van den Akker
Date: 12:51:53 11/23/99
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On November 23, 1999 at 06:40:11, Dominic Marcello wrote: >>Why? >> >>I have to check if the hash move is correct. >>Now I can look in my generated moves and this cost only 0.15 seconds. >> >>Otherwise I must write seperate code to check if the >>hash move is legal. >> >> > > Think about it.. the hash move is always legal. The entry you look up is for >the position you're in at the moment, so since they are the same position, they >have the same set of legal moves. > Furthermore, if the hash move does not cause a cutoff and you generate the >rest of the moves, it's OK if the hash move is replayed because all that will >happen is that at the next ply the position will be in the hash table already >since it was already searched (assuming you're hash table is large enough) > To save even more time, you can generate just the winning captures after if >the hash move does not cut-off, and then just non-captures if the winning >captures do not cause cut-off, and then just losing captures. 1. 2 positions can have the same hash key because there are mutch more chess position 10^100 then entries in a hash tabel. This means that if you don't check the hash move than this can be an illegal move (move for an other position with the same hash key) 2. One of the first things I do in a node is to check if the hash value causes a cutoff. If this is not the case I try the hash move first. BvdA
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