Tilings and tiling systems are an abstract concept that arise both as a computational model and as a dynamical system. In this paper, we prove an analog of the theorems of Fagin [11] and Selman and Jones [17] by characterizing sets of periods of tiling systems by complexity classes.

Imbricational crown formation times (ICFTs) estimated from the number of perikymata on tooth surfaces are error-prone because the number of days between adjacent perikymata varies across individuals and species, and is only visible within tooth microstructure. We investigated striae of Retzius (SR) numbers (analogous to perikymata numbers), SR periodicities (days between SR or perikymata), and ...

BACKGROUND Periodic leg movements (PLM) during sleep consist of involuntary periodic movements of the lower extremities. The debated functional relevance of PLM during sleep is based on correlation of clinical parameters with the PLM index (PLMI). However, periodicity in movements may not be reflected best by the PLMI. Here, an approach novel to the field of sleep research is used to reveal int...

This paper is devoted to classical Bott periodicity, its history and more recent extensions in algebraic and Hermitian K-theory. However, it does not aim at completeness. For instance, the variants of Bott periodicity related to bivariant K-theory are described by Cuntz in this handbook. As another example, we don’t emphasize here the relation between motivic homotopy theory and Bott periodicit...

Cappell and Weinberger gave a geometric interpretation of the Siebenmann periodicity phenomena. This near-periodicity on the structure sets of topological manifolds was originally demonstrated in an indirect way from the periodicity of the simply-connected quadratic L-groups, see Nicas and Siebenmann (1977). In particular it was shown for a topological manifold M , dim M ≥ 5, with structure set...