Author: Ricardo Gibert
Date: 09:29:08 08/04/99
Go up one level in this thread
On August 04, 1999 at 09:19:56, Robert Hyatt wrote: >On August 03, 1999 at 23:13:13, Ricardo Gibert wrote: > >>On August 03, 1999 at 21:54:23, Robert Hyatt wrote: >> >>>On August 03, 1999 at 15:34:54, Ricardo Gibert wrote: >>> >>>>On August 03, 1999 at 14:28:04, Robert Hyatt wrote: >>>> >>>>>On August 03, 1999 at 10:28:25, Ricardo Gibert wrote: >>>>> >>>>>>On August 03, 1999 at 09:00:33, Robert Hyatt wrote: >>>>>> >>>>>>>On August 03, 1999 at 04:45:07, Ricardo Gibert wrote: >>>>>>> >>>>>>>>On August 03, 1999 at 04:32:27, Bruce Moreland wrote: >>>>>>>> >>>>>>>>> >>>>>>>>>On August 02, 1999 at 22:47:14, Ricardo Gibert wrote: >>>>>>>>> >>>>>>>>> >>>>>>>>>>Your post is a little ambiguous. Are you saying Nalimov EGTB is a shortest mate >>>>>>>>>>EGTB for all the 5 man endings? How would the tables be generated? >>>>>>>>>> >>>>>>>>>>I would be surprised if all the endings covered by the Nalimov EGTB are of the >>>>>>>>>>shortest mate variety. I would also be disappointed for the reason indicated. >>>>>>>>>>Some endings (other than KQKR which a computer program can win in about 34 >>>>>>>>>>moves) would be "impossible" to win using such a TB due to the 50 move rule. >>>>>>>>> >>>>>>>>>I would be suprised if the Nalimov tables are *not* distance to mate. The only >>>>>>>>>publicly available distance to conversion tables that I know of are the Thompson >>>>>>>>>tables. >>>>>>>> >>>>>>>>Shortest mate EGTB also has the defect of possibly concluding that an ending is >>>>>>>>drawn due to the 50 move when it is actually winning. By the way, I think this >>>>>>>>issue can be cleared up by noting that "distance to mate" is not necessarily the >>>>>>>>same as "shortest mate". >>>>>>> >>>>>>> >>>>>>> >>>>>>>first, 50 move draw is _not_ included. How could it be? Because you have >>>>>>>_no_ idea what position you will enter the database at... >>>>>>> >>>>>>>and distance to mate _is_ "shortest distance to mate" absolutely... >>>>>>> >>>>>>Then this means the EGTB will prefer a mate in 51 without pawns moves or >>>>>>captures to a mate in 52 with a pawn move or capture before the 50 move rule >>>>>>kicks in. It will draw winning positions. Undesirable and unnecessary. >>>>>>Fortunately rare. >>>>>>> >>>>> >>>>> >>>>>yes... but this is a problem no matter what. Because the tablebase is just >>>>>a file that is indexed by piece location, and it provides mated-in-N, draw, or >>>>>mate-in-N. It has _no_ idea about prior positions and what might have >>>>>transpired before reaching this position. It can't even tell if this position >>>>>is a successor of another position in this file, or if it was reached via a >>>>>capture with a zero 50-move counter. >>>> >>>>prior positions are irrelevant. >>>> >>> >>>you are wrong here. I play move A, then move B (which unmakes move A), >>>then move A again, then move B again, and now I probe the table, and it >>>says if you play move X you win the rook in 4 moves. Unfortunately, >>>a couple of moves before you win the rook, you play move A again and >>>the position is repeated and the game ends as a draw. >> >>The EGTBs hits should be "part" of the eval. A tool. You catch 3 fold reps the >>same way you always do. For example, distance to mate also would have this >>"problem". What difference does it make if you find mate or win of a rook? > >> >>Besides, after you play A the 1st time, you probe and find move X to win the >>rook. No draw. >> > > >this is going in circles. This was _my_ argument. then _you_ pointed out >you were talking about doing a probe _after_ an adjournament. And there, the >problem is going to come up and there is no solution for it. > >If my program plays the whole game, this will _never_ be a problem. If you >give it a position to play after someone else has played a bunch of moves, >then this wil never work properly. > It will be a problem regardless (unless you also provide the game score) of how you do it. "My way" addresses the 50-move problem. > > >>> >>>If you don't have state information in the database, there is _no_ way >>>to probe it and ask about such things.. because it says you can capture >>>a piece in 29 moves, but how many _prior_ positions of yours do you repeat >>>before doing so? >>> >>>This is an old discussion. There are _many_ problems here... >>> >>> >>> >>>>> >>>>>deep mates are going to be a problem in 6 piece files, no doubt about it. It >>>>>would be interesting to see if there are already violations of this in the 5 >>>>>piece files... >>>>> >>>>> >>>>> >>>>>>> >>>>>>> >>>>>>>>> >>>>>>>>>And yes, the tables do suffer from the possible problem that you mentioned, >>>>>>>>>although this should be extremely rare in practice. >>>>>>>>> >>>>>>>>>bruce
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