Author: Dave Gomboc
Date: 11:17:58 05/19/99
Go up one level in this thread
On May 19, 1999 at 11:28:51, KarinsDad wrote: >On May 19, 1999 at 02:40:34, Dave Gomboc wrote: > >>On May 19, 1999 at 01:54:47, KarinsDad wrote: >> >>>Dann, >>> >>>Here is the Shirov Kasparov game I mentioned. I just picked a random game. As >>>can be seen, this game maxed out at 142 bits (if Shirov would have castled, say >>>at move 13, it could have been 150 bits or slightly higher). The two numbers on >>>the left are the number of bits required after each move. The entire advantage >>>of this schema is that most black pieces do not require a color bit until a >>>white piece or pawn is taken. Once this happens, (in this game at move 3 since >>>it was a Sicilian), that condition no longer holds. However, only 2 pawns or one >>>piece have to be taken in the entire game to basically ensure that 160 bits is >>>the maximum, so by move 4 in this game, the chances of it going above 160 bits >>>are negligible. >>> >>>It would be interesting if someone could find a position from a real game that >>>could get to 161 bits or more, but I doubt that will happen. >>> >>>KarinsDad :) >>> >>>125 125 1.e4 c5 >>>126 126 2.Nf3 d6 >>>126 137 3.d4 cxd4 >>>135 136 4.Nxd4 Nf6 >>>137 137 5.Nc3 a6 >>>139 139 6.Be3 Ng4 >>>139 139 7.Bg5 h6 >>>139 139 8.Bh4 g5 >>>139 140 9.Bg3 Bg7 >>>141 141 10.Be2 h5 >>>137 133 11.Bxg4 hxg4 >>>141 142 12.0-0 Nc6 >>>142 138 13.Nf5 Bxc3 >>>134 135 14.bxc3 Qa5 >>>134 134 15.Qxg4 f6 >>>134 132 16.Rab1 Qxc3 >>>132 132 17.Rfd1 Ne5 >>>128 124 18.Bxe5 Qxe5 >>>124 124 19.g3 b5 >>>124 122 20.c4 bxc4 >>>122 122 21.Qf3 c3 >>>122 123 22.Rbc1 Bb7 >>>121 119 23.Qxc3 Bxe4 >>>117 113 24.Nxd6+ exd6 >>>113 109 25.Re1 Qxc3 >>>106 106 26.Rxc3 d5 >>>106 114 27.f3 Kf7 >>>110 110 28.fxe4 Rhe8 >>>110 110 29.Rc7+ Kg6 >>>110 108 30.Rf1 dxe4 >>>110 108 31.Rc6 Rf8 >>>108 108 32.Re6 Rae8 >>>108 108 33.Rfxf6+ Rxf6 >>> 98 98 34.Rxe8 Kf5 >>> 98 98 35.Kf2 Rh6 >>> 98 98 36.Rf8+ Ke5 >>> 98 98 37.Re8+ Kf5 >>> 98 98 38.Rf8+ Ke5 >>> 1/2-1/2 >> >>What a waste of bits! :) The entire game should have been storable in far >>fewer. To know exactly how many, take the number of legal moves from each >>position, multiple them all together to get a big number, P. Find n such that P >>/ 2^n < 0. n = the number of bits you need to store the raw positions (no >>1/2-1/2, player names, etc.) >> >>I didn't do it for this game, but n will likely be in the low hundreds. You are >>using several thousand bits to represent the game. >> >>Dave > >The point of the data structure is to store any position when you DO NOT have an >entire game, but just a position. The illustration above was only being used to >show how difficult it will be in real games to go over the 160 bit limit in the >structure. As can be seen (and, of course, this is only one game), most of the >positions in this game could be represented in 140 bits or less (considerably >less than the 160 bits). Yeah, I know. I guess I was thinking that if you were planning on storing a few of those positions, it would be cheaper to store all of them. :-) >For example, you could use this structure to store a bunch of interesting >positions in a database. The suggested moves after the position would be stored >in a different format. > >Of course you can store a game in much fewer bits! That was not the point of it. >The point of it was whether you could store a position in fewer bits. > >KarinsDad :) Dave
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