Combinatorial information distance

Abstract

Let $|A|$ denote the cardinality of a finite set $A$. For any real number $x$ define $t(x)=x$ if $x\geq1$ and 1 otherwise. For any finite sets $A,B$ let $\delta(A,B)$ $=$ $\log_{2}(t(|B\cap\bar{A}||A|))$. We define {This appears as Technical Report # arXiv:0905.2386v4. A shorter version appears in the {Proc. of Mini-Conference on Applied Theoretical Computer Science (MATCOS-10)}, Slovenia, Oct. 13-14, 2010.} a new cobinatorial distance $d(A,B)$ $=$ $\max\{\delta(A,B),\delta(B,A)\} $ which may be applied to measure the distance between binary strings of different lengths. The distance is based on a classical combinatorial notion of information introduced by Kolmogorov.