t***r
发帖数: 3 | 1 In the case sigma={0,1}, one choice can be the subset of all
strings of length n that contain even (or alternatively,
odd) number of 1's. There is no hope of finding a subset
containing more than 2^(n-1) strings that satisfies the
specified condition (just organize all 2^n strings into
pairs, each pair consisting of two strings that differ at
exactly one position. For example, xxxx0 paired with xxx1,
xxx ranges over all combinations. Then each set satisfying
the specified condition may contain a |
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