Author: Dave Gomboc
Date: 10:41:37 07/19/99
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On July 19, 1999 at 06:14:45, Vincent Diepeveen wrote: >On July 19, 1999 at 00:14:28, Dave Gomboc wrote: > >>On July 18, 1999 at 21:11:20, Vincent Diepeveen wrote: >> [snip] >>>That's not true, as in the worst case your window is a pawn off. >>>So the first 5 researches are searching space which is completely useless, >>>where in PVS the search overhead only depends upon move ordering. >> >>The more useless the search, the quicker it terminates. If you're a pawn off, a >>cutoff should be extremely quick. Searches that are close to the proper value >>take longer, precisely because they are searching space that is not "completely >>useless", as you put it. And that effort will be caught in the hash table, so >>you don't have to search it twice. > >That's not entirely true. > >a) it's overhead which PVS doesn't search mtd(f) searches minimal trees to prove what it needs to prove. PVS also has a lot of overhead that mtd(f) doesn't search. >b) you do not get it from hashtable as you search with a way lower bound > next iteration, and then another lower research, where nullmove > has the habit to give for alfa and beta scores back which are simply > equal to alfa and beta. So you do need to research and can't > use hashtable cheap When the score doesn't move far, a ton of the re-search is in the hash table. When it does, the first search didn't take very long anyway. [snip] Dave
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