Frequency covers for strings

We study a central problem of string processing: the compact representation of a string by its frequently-occurring substrings. In this paper we propose an effective, easily-computed form of quasi-periodicity in strings, the frequency cover; that is, the longest of those repeating substrings u of w, |u| > 1, that occurs the maximum number of times in w. The advantage of this generalization is that it is not only applicable to all strings but also that it is the only generalized notion of cover yet proposed, which can be computed efficiently in linear time and space. We describe a simple data structure called the repeating substring frequency array (