Author: Dave Gomboc
Date: 21:16:30 01/26/00
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On January 26, 2000 at 00:45:13, Robert Hyatt wrote: >On January 25, 2000 at 13:07:38, Dave Gomboc wrote: > >>On January 24, 2000 at 09:09:50, Steve Coladonato wrote: >> >>>On January 23, 2000 at 17:06:14, José de Jesús García Ruvalcaba wrote: >>> >>>>On January 23, 2000 at 11:45:29, Steve Coladonato wrote: >>>> >>> >>><snip> >>> >>>>> >>>>>From this and Michel's response, is it not true then that the "best move" is >>>>>stored in the tablebases and if so why have the program run thru the legal moves >>>>>and probe the tablebases for each one? If you're concerned about legal moves, >>>>>pick the best move as noted in the tablebase and then check to see if it's legal >>>>>(in case of some error in the tablebase). I realize the CPU time here is >>>>>minimal and I'm just trying to get the logic behind the use of tablebases. >>>>> >>>>>Thanks again. >>>>> >>>>>Steve >>>> >>>> Tablebases do not store moves (not even the "best" move). They only store >>>>scores for positions. >>>> (Assuming the root position is in tablebases and that there are no tablebases >>>>missing) the program has to search all the legal ply-one moves, and probe for >>>>every resulting position. This returns a score for each one, and the highest >>>>scoring one is chosen. >>>>José. >>> >>>Jose, >>> >>>After I sent the response I realized that the program would have to generate a >>>move and then find that position in the tablebase. The table Michel included >>>was really only a representation of the tablebase, not the structure of the >>>tablebase. So the (init+move) would have to found again using the hash lookup >>>and the scores for all (init+move)'s would be evaluated to determine the best >>>one. >>> >>>Thanks. >>> >>>Steve >> >>Sounds like you've got it all. >> >>Dave > > >Except there is no "hash lookup". It is an exact probe into the table made >possible by computing a very precise table index that is unique for each >possible configuration of pieces on the board. ... which is the hash function. (You might have read the post out of context.) Dave
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