Author: Robert Hyatt
Date: 06:19:56 08/04/99
Go up one level in this thread
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. >> >>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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