Author: John Coffey
Date: 14:51:48 09/27/98
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On September 27, 1998 at 17:45:17, Serge Desmarais wrote: >On September 20, 1998 at 18:47:20, John Coffey wrote: > >>I found this on http://www.xs4all.nl/~verhelst/chess/search.html ........... >> >>"Null move heuristic >> >>The null move heuristic is a method of skipping searches in parts of the tree >>where the position is good enoigh. This is tested by doing a null move (i.e. >>passing, doing no move at all) and then seraching with reduced depth. If the >>result of this is higher than beta, no further search is done; if the result is >>lower than beta we do a normal search. >> >>The null move heuristic has big dangers because it can fail to detect deep >>combinations. On the other hand it can save a lot of time by skipping large >>parts of the search tree. " >> >>John Coffey > > > So I assume the "null move technique" was invented at a time when computers >were fairly slow and so the programmers had to find some means of bypassing this >by all sorts of techniques. Now that computers are faster than "Mach 3", it is >no more necessary to take the chance of missing deep combinations? They will >reach these with normal search and selective extensions? I had a Super Nine from >Fidelity Electronics in the 80's and it needed days to reach a depth of 9-11 >plies, even in very simple ending positions! > >Serge Desmarais Actually null moves pruning is one of the reasons why modern programs don't take days to get to 11 plys. John coffey
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