Recurrent word


In mathematics, a recurrent word or sequence is an infinite word over a finite alphabet in which every factor occurs infinitely many times. An infinite word is recurrent if and only if it is a sesquipower.
A uniformly recurrent word is a recurrent word in which for any given factor X in the sequence, there is some length nX such that X appears in every block of length nX. The terms minimal sequence and almost periodic sequence are also used.

Examples