Approximate periodicity in strings

In many application areas (for instance, DNA sequence analysis), it becomes important to compute various kinds of "approximate period" of a given string y. Here we discuss three such approximate periods and the algorithms which compute them: an Abelian generator, a cover, and a seed. Let u be a substring of y. Then u is an Abelian generator of y iff y is a concatenation of substrings which are permutations of u; u is a cover of y iff every …