Author: Robert Hyatt
Date: 15:08:31 11/13/01
Go up one level in this thread
On November 13, 2001 at 13:40:53, Miguel A. Ballicora wrote: >On November 13, 2001 at 13:23:12, Robert Hyatt wrote: > >>On November 13, 2001 at 12:03:31, Uri Blass wrote: >> >>>On November 13, 2001 at 10:09:30, Robert Hyatt wrote: >>> >>>>On November 13, 2001 at 08:31:09, William Penn wrote: >>>> >>>>>I suspect this has been discussed before but I didn't pay attention, so please >>>>>pardon my redundancy. If you could just point me in the right direction, much >>>>>appreciated... >>>>> >>>>>Can't we make some assumptions without compromising very much practical playing >>>>>strength and significantly reduce the size of the endgame tablebases? For >>>>>example it seems a waste to generate separate positions for "white to move" and >>>>>"black to move". >>>> >>>>How would you handle all the common zugzwang positions? black king at e6, >>>>white king at e4, white pawn at e3. White to move draws. Black to move >>>>loses. >>> >>>There is a solution for it. >>>You probe the tablebases only when the right side is to move. >>> >>>I understand that calculating the moves when you are in a tablebases position >>>becomes more comlicated but it can be solved by 2 ply search. >>> >>>Uri >> >> >>This implies you _only_ stop the search when a specific side is on move. >>This will break the basic idea of minimax to a degree, because some positions >>will be searched one ply deeper than they should be, and that means comparing >>apples and oranges in the evaluations those two searches return. > >Everytime you find a tablebase position, you ask if white is on the move. >If it is, you do a 1 ply search from here that will return the same result >as if you have both tablebases and you probe immediately. > >Regards, >Miguel That requires N tablebase probes for the N moves at the next ply... which was one of the problems. It also means that it is _possible_ that you don't get a tablebase hit at the next ply but you are one ply deeper than you should be, which is another problem.
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