## Tilings and rotations on the torus: A two-dimensional generalization of Sturmian sequences.(English)Zbl 0970.68124

Summary: We study a two-dimensional generalization of Sturmian sequences corresponding to an approximation of a plane: these sequences are defined on a three-letter alphabet and code a two-dimensional tiling obtained by projecting a discrete plane. We show that these sequences code a $$\mathbb{Z}^2$$-action generated by two rotations on the unit circle. We first deduce a new way of computing the rectangle complexity function. Then we provide an upper bound on the number of frequencies of rectangular factors of given size.

### MSC:

 68R15 Combinatorics on words

### Keywords:

Sturmian sequences
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