Author: David Rasmussen
Date: 08:42:54 12/07/02
Go up one level in this thread
On December 07, 2002 at 11:25:44, Robert Hyatt wrote: >> >>I hadn't either until now. But I am pretty sure that Bob sais something about >>this happening once in 100 games or so. > >That was an estimate. Think about the math. You are collapsing some 2^168 >positions into 2^64 hash space. That is a _huge_ aliasing problem. So the >probability of getting duplicates is not just a probability, it is an absolute >certainty... I know that. I am not saying that it will not happen. I know it will. But I am asking about the frequency. When doing math on these beasts people tend to just assume that everything is random. It isn't. The subspace visited by a 12-ply search with a 64 MB hashtable is not the same as the whole game tree. As I said: we don't care if there are signature collisions between two positions that are "far" from eachother. The probablility for it happening within the history of a seach with a hash table, is far less (apparently). And it is not simple to estimate how much. So I was asking about people's experiences of this frequency, because I didn't believe such naive reasoning anyway. If the theory isn't corresponding with experience, fix the theory. /David
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