Binary strings of finite VC dimension

01/16/2021

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by   Hunter R Johnson, et al.

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Any binary string can be associated with a unary predicate P on ℕ. In this paper we investigate subsets named by a predicate P such that the relation P(x+y) has finite VC dimension. This provides a measure of complexity for binary strings with different properties than the standard string complexity function (based on diversity of substrings). We prove that strings of bounded VC dimension are meagre in the topology of the reals, provide simple rules for bounding the VC dimension of a string, and show that the bi-infinite strings of VC dimension d are a non-sofic shift space. Additionally we characterize the irreducible strings of low VC dimension (0,1 and 2), and provide connections to mathematical logic.