We derive simple linear, inhomogeneous recurrences for the variance of the index by utilising the fact that the generating function for the distribution of the number of positive eigenvalues of a Gaussian unitary ensemble is a τ-function of the fourth Painlevé equation. From this we deduce a simple summation formula, several integral representations and finally an exact hypergeometric function ...

In this paper, sufficient conditions are established for the oscillatory and asymptotic behavior of higher–order half–linear delay difference equation of the form ∆(pn(∆ (xn + qnxτn)) ) + rnx β σn = 0, n ≥ n0, where it is assumed that ∑∞ s=n0 1/p 1/α s < ∞. The main theorem improves some existing results in the literature. An example is provided to demonstrate the effectiveness of the main result.

Necessary and sufficient conditions for the asymptotic stability of a class of difference equations with three parameters are obtained. These conditions are expressed in terms of subsets of the parameter space.

In this paper we put into relation the index of an infinite aperiodic word and its recurrence function. With the use of this relation, we then give a new characterization of Sturmian words. As a byproduct, we give a new proof of theorem of Damanik and Lenz describing the index of a Sturmian word in terms of the continued fraction expansion of its slope.