Mikhail V. Vyugin

C.H.~Bennett, P.~G\'acs, M.~Li, P.M.B.~Vit\'anyi, and W.H.~Zurek

have defined information distance between two strings $x$, $y$

as

$$

d(x,y)=\max\{ K(x|y), K(y|x) \}

$$

where $K(x|y)$ is the conditional Kolmogorov complexity.

It is easy to see that for any string $x$ and any integer $n$

there is a string $y$ ...
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