Rectangular p-periodicity and pq-periodicity of a rational difference system

Periodicity in Rectangular Arrays

We discuss several two-dimensional generalizations of the familiar Lyndon-Schützenberger periodicity theorem for words. We consider the notion of primitive array (as one that cannot be expressed as the repetition of smaller arrays). We count the number of m×n arrays that are primitive. Finally, we show that one can test primitivity and compute the primitive root of an array in linear time.

Periodicity in a System of Differential Equations with Finite Delay

The existence and uniqueness of a periodic solution of the system of differential equations d dt x(t) = A(t)x(t − ) are proved. In particular the Krasnoselskii’s fixed point theorem and the contraction mapping principle are used in the analysis. In addition, the notion of fundamental matrix solution coupled with Floquet theory is also employed.  

Pointwise almost periodicity in a generalized shift dynamical system

... 

Two-Dimensional Periodicity in Rectangular Arrays

String matching is rich with a variety of algorithmic tools. In contrast, multidimensional matching has had a rather sparse set of techniques. This paper presents a new algorithmic technique for two-dimensional matching: periodicity analysis. Its strength appears to lie in the fact that it is inherently two-dimensional. Periodicity in strings has been used to solve string matching problems. Mul...

Periodicity and Almost-periodicity