Author: blass uri
Date: 10:37:09 10/04/98
Go up one level in this thread
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 do not understand how distance to the next capture or moving a pawn may cause problems because what happened before is not relevant > 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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