Author: José de Jesús García Ruvalcaba
Date: 09:56:39 01/30/99
Go up one level in this thread
On January 29, 1999 at 19:20:50, Melvin S. Schwartz wrote: > >On January 29, 1999 at 18:10:02, José de Jesús García Ruvalcaba wrote: > >>On January 29, 1999 at 17:46:45, Melvin S. Schwartz wrote: >> >>>According to the manual of my Mephisto atlanta, it states: >>>"The program in this chess computer normally uses a Selective Search algorithm. >>>This allows the computer to see combinations that would otherwise take much >>>longer to compute. Turning this option off by choosing -SEL makes the program >>>switch to a powerful Brute Force algorithm. This search method minimizes the >>>risk of an occasional oversight. Note: The Problem Solving Levels always use the >>>Brute Force method." >>>This explanation of the two types of searches would seem to me that Brute Force >>>would see what Selective Search can see and more since it minimizes the risk of >>>an occasional oversight. And it seems that since Selective Search is faster, it >>>wouldn't go as deep as Brute Force. I know it is somewhat confusing comparing >>>all to what you said. Now, can you make some sense of it knowing what the manual >>>says? If the tech guy in Hong Kong is wrong, then he should be selling shoes >>>instead being a technician. Seriously, I would appreciate your evaluation of >>>what the manual says. >>>Thank you, >>>Mel >> >> I do not have a Mephisto Atlanta; I answer from what I have read about brute >>force and selective search in general. >> At the same time control, both search algorithms will see very differente >>things. The brute force one will look at all the variations to about the same >>depth; while the selective search will look much deeper to some variations than >>others, its longest variations will be much longer that those of the brute force >>method. >> The selective search method risks an oversight in its less deep variations. The >>brute force method wastes a lot of time in irrelevant moves. > >Thank you for responding. However, my real question is still not answered. Which >method produces a higher chess rating. In other words, when they rate these >machines; for example, the Novag Diamond 11 Swedish ELO 2220 and the Mephisto >atlanta Swedish ELO 2280, which method do they use? Selective Search or Brute >Force. Which method produces a higher level of chess??? Which method is >better??? The manual of my Mephisto does state that Brute Force is used in the >Problem Solving Levels. There must be a reason why they have designed the chess >computer to operate that way. Anyone with information regardng this confusing >issue would be appreciated. >Thank you, >Mel As far as I understand, the SSDF rates the machines with their default settings. For your Atlanta mahcine it means the selective search. I do not know if it plays chess better or worse than with brute force. There is no way to compare the two methods in general: there are too many ways to be selective, and they can produce very different results. If you get two Atlanta machines, you can play a match between its selective search against its brute force search, but that will only have meaning for the Atlanta and the results could not be extrapolated. I think brute force is used to solve problems because many key moves in composed positions are very unnatural, and would be quickly rejected by the selective search after a shallow search (the machine needs a deeper search to find they are good moves).
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