Author: Robert Hyatt
Date: 13:47:46 10/04/98
Go up one level in this thread
On October 04, 1998 at 13:58:04, blass uri wrote: > >On October 04, 1998 at 13:37:09, blass uri wrote: > >> >>On October 04, 1998 at 13:06:30, Robert Hyatt wrote: >> >>>On October 04, 1998 at 11:51:20, blass uri wrote: >>> >>>> >>>>On October 04, 1998 at 10:00:09, Robert Hyatt wrote: >>>> >>>>>On October 04, 1998 at 05:24:42, blass uri wrote: >>>>> >>>>>> >>>>>>On October 03, 1998 at 22:07:23, Robert Hyatt wrote: >>>>>> >>>>>> >It really wouldn't help, because this would reduce the size of the current >>>>>>>tablebases by 1/4, because they use 8 bit values. >>>>>> >>>>>>How can you use 8 bit values >>>>>>only to store the move you may need 6 bits because you may have more than 32 >>>>>>legal moves even only with king and queen. >>>>>> >>>>>>do you mean 8 bits only to store the result and that the tablebases use more >>>>>>than 8 bits for position(8 bits for result and 5 or 6 bits for the move)? >>>>>> >>>>>>you can save space in the harddisk by not storing the result and computing it by >>>>>>playing the right moves against yourself but in this case you are slower. >>>>>> >>>>>>Uri >>>>> >>>>> >>>>> >>>>>there are no "moves" in the database. It is a huge stream of bytes indexed by >>>>>a "Godel" number that is simply a concatenation of the squares each piece sit >>>>>on. IE let's number the squares a1=0... h8=63. put the white knight on a1, >>>>>white king on b1, white bishop on c1 and black king on d1. All we do is take >>>>>the 4 squares and compute b1<<18 + a1<<12 + c1<<6 + d1... which gives us a >>>>>number that indexes into the database, and the value we find there is +Mate in >>>>>N, -Mate in N, or Draw (0). >>>>> >>>>>No moves, no pieces, etc. The pieces (the squares they stand on) form the >>>>>key, the result at that position is how many moves to mate, or else "draw" >>>> >>>>I understand >>>>You can use the exact result of mate in N to compute the move. >>>> >>>>I think that 7 bytes may be enough to store the result if instead of storing >>>>mate in how many moves you store only the number of moves before the next >>>>capture or the next moving of a pawn >>>>because of the 50 moves rule you have only 101 possible results >>>>draw or win in 1-50 moves for you or win in 1-50 moves for the opponent >>>> >>>>Uri >>> >>> >>>I assume you mean "seven bits". But this doesn't tell me anything about how >>>to choose between two moves in the tree, when one is mate in 10 and one is >>>mate in 30. And if I keep choosing mate in 30, I encounter problems, because >>>I can end up drawing by the 50 move rule, since the "distance to conversion" >>>doesn't factor in the moves played *before* this position was reached, only >>>what happens *after* this position was reached... >>> >>>In any case, distance to mate is trivial to use, and never screws up. >> >>theoretically distance to mate may cause problems becuase if one is mate in 70 >>that is practically a draw because of the 50 move rule and the second is mate in >>80 that is not a draw because there is a capture after 40 moves than mate in 80 >>is the right move. > >I understand that the tablebases in the first case may say draw and solve this >problem >> >>I do not understand how distance to the next capture or moving a pawn may cause >>problems because what happened before is not relevant > >I think if you imagine the target is not to do mate as soon as possible but to >do capture that lead to winning or moving a pawn that lead to winning then there >is no problem because the distance to win is always become shorter >and after a capture you have a new game > >Uri the problem in the fritz game that was posted on r.g.c.c several months ago (and I had seen at least one of these OTB vs crafty on ICC also) was that it took the path leading to a "conversion" in 3 moves... but overlooked that the position led to getting mated in *two*moves... >> >>> I can >>>show you cases where fritz lost in drawn positions because it took the move >>>that led to the "most distant conversion" and overlooked a mate in 2 on the >>>board... >> >>I want to see >> >>Uri
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