Uniformly_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.[1][2][3] An infinite word is recurrent if and only if it is a sesquipower.[4][5]
A uniformly recurrent word is a recurrent word in which for any given factor X in the sequence, there is some length nX (often much longer than the length of X) such that X appears in every block of length nX.[1][6][7] The terms minimal sequence[8] and almost periodic sequence (Muchnik, Semenov, Ushakov 2003) are also used.