Author: KarinsDad
Date: 10:23:33 05/15/99
Go up one level in this thread
On May 15, 1999 at 11:36:18, Andrew Dados wrote: > > Ok.. let's summarize.. Your format ends up with 22 bytes and does not >support all legal positions.. Now let's check way easier schema: >64 bits locations = 8 bytes >32x4 bits piece+color flag =16 bytes >50 move + ep+ castling rights+ side to move = 2 bytes >total gets to 26 but *any* 32 piece position is supported and way easier/faster > to code.. >As usual - trade off.... > > -regards - > Andrew You forgot move by repetition, 2 more bits. So, a total of 27 bytes for your schema. Our schema is harder/slower to code. You are absolutely correct. However, the decompression will not be THAT much slower than the schema you mentioned, so once it is coded and debugged, the main difference is the smaller size. The original post asked for the smallest representation since for the reasons in which you would wish to use this (such as an opening book), you want tight compression, not ease of accessing. The hard disk access is WAY slower than the decompression in memory if you are accessing a lot of hard disk simultaneously. Our schema can support all legal positions in 25 bytes. Our schema can support all legal positions that would every show up in a real game in 22 bytes (and if you were concerned, you could increase it to 23 bytes and never have to worry about it). Our schema can support an opening book where you do not need the 50 move rule in 21 bytes. I doubt our schema is the best, but it comes closer to the original post of the tightest compression possible than the simple schema you mentioned by several bytes. Also, from what I can tell, this problem has been solved before by others to the level at which we did it (i.e. we just reinvented the wheel the exact same way, so we cannot take credit for it). KarinsDad :)
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