Author: David Rasmussen
Date: 01:01:21 02/10/01
Go up one level in this thread
On February 09, 2001 at 19:34:03, Ricardo Gibert wrote: > >So far the conclusions I've come up with are: > >(1) A Key = 0 should be excluded, since positions with a particular piece on a >particular square will produce the same hash signature as the same position >without that piece. This excludes all linear codes, which is obviously a good thing to do, because a linear code would mean that c = a xor b will be a codeword if a and b are codewords. This means that with exactly three xors you could get the codeword zero. With 800 codewords, this means that there are lots of different ways to get 0 which would mean that 0 couldn't possible denote just one position. >(3) Pairs of keys of the form x and ~x, since 2 such pairs will XOR to zero. This criterion can be met by saying that the code should be non-linear. There's nothing wrong with a high hamming distance in general, as long as we have a non-linear code. >(4) Pairs with a close hamming distance to x and ~x should also be excluded. What do you mean by this? Hamming distance is a number, x and ~x are codewords. >(5) A key set with a hamming distance > 21 and < 43 with respect to each other >*and* to zero should satisfy (1)-(4) above can be quickly produced within the >program without having to read in a file with the keys. Just use the same random >number seed. > Sure, but we might be able to do better. >I'm trying to find sources on the net to verify these conclusions, but so far no >luck. What do you think? Search for coding theory.
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.