Nous montrons que le polygone de Newton d’une équation aux $q$-différences linéaire ne dépend que du module aux $q$-différences correspondant. Nous interprétons les résultats classiques de factorisation convergente de Adams-Birkhoff-Guenther en termes d’existence d’une filtration canonique par les pentes. De plus, le gradué associé possède d’excellentes propriétés fonctorielles et tensorielles.

The purpose of these notes is to give a short survey of an interesting connection between partition functions of supersymmetric gauge theories and hypergeometric functions and to present the recent progress in this direction.

This paper aims at discussing asymptotic behaviour of nonoscillatory solutions of the forced fractional difference equations of the form $$\begin{array}{cc}\hfill {\Delta }^{\gamma }u\left(\kappa \right)& +\Theta [\kappa +\gamma ,w(\kappa +\gamma \left)\right]\hfill \\ \hfill =& \Phi (\kappa +\gamma )+{\rm Y}(\kappa +\gamma )w^{\nu }(\kappa +\gamma )+\Psi [\kappa +\gamma ,w(\kappa +\gamma )],\kappa \in {\mathbb{N}}_{1-\gamma },\hfill \\ \hfill u_0=& c_0,\hfill \end{array}$$ where ${\mathbb{N}}_{1-\gamma }=\{1-\gamma ,2-\gamma ,3-\gamma ,\cdots \}$, $0<\gamma \le 1$, ${\Delta }^{\gamma }$ is a Caputo-like fractional difference operator. Three cases are investigated by using some salient features of discrete fractional calculus and mathematical inequalities. Examples are presented to illustrate the validity of the theoretical results.

Some $q$-analysis variants of Hardy type inequalities of the form $${\int }_0^b{\left(x^{\alpha -1}{\int }_0^x{t}^{-\alpha }f\left(t\right){\mathrm{d}}_{q}t\right)}^p{\mathrm{d}}_{q}x\le C{\int }_0^b{f}^p\left(t\right){\mathrm{d}}_{q}t$$ with sharp constant $C$ are proved and discussed. A similar result with the Riemann-Liouville operator involved is also proved. Finally, it is pointed out that by using these techniques we can also obtain some new discrete Hardy and Copson type inequalities in the classical case.

This paper is divided in two parts. In the first part we study a convergent $q$-analog of the divergent Euler series, with $q\in (0,1)$, and we show how the Borel sum of a generic Gevrey formal solution to a differential equation can be uniformly approximated on a convenient sector by a meromorphic solution of a corresponding $q$-difference equation. In the second part, we work under the assumption $q\in (1,+\infty )$. In this case, at least four different $q$-Borel sums of a divergent power series solution of an irregular singular...

We present a version of Opial's inequality for time scales and point out some of its applications to so-called dynamic equations. Such dynamic equations contain both differential equations and difference equations as special cases. Various extensions of our inequality are offered as well.

In this work, necessary and sufficient conditions for the oscillation of solutions of 2-dimensional linear neutral delay difference systems of the form $$\Delta \left[\begin{array}{c}x\left(n\right)+p\left(n\right)x(n-m)\\ y\left(n\right)+p\left(n\right)y(n-m)\end{array}\right]=\left[\begin{array}{cc}a\left(n\right)& b\left(n\right)\\ c\left(n\right)& d\left(n\right)\end{array}\right]\left[\begin{array}{c}x(n-\alpha )\\ y(n-\beta )\end{array}\right]$$ are established, where $m>0$, $\alpha \ge 0$, $\beta \ge 0$ are integers and $a\left(n\right)$, $b\left(n\right)$, $c\left(n\right)$, $d\left(n\right)$, $p\left(n\right)$ are sequences of real numbers.