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In this paper, a relationship between the zeros and critical points of a polynomial *p*(*z*) is established. The relationship is used to prove Sendov’s conjecture in some special cases.

A ﬂuid queueing system in which the ﬂuid ﬂow in to the buffer is regulated by the state of the background queueing process is considered. In this model, the arrival and service rates follow chain sequence rates and are controlled by an exponential timer. The buffer content distribution along with averages are found using continued fraction methodology. Numerical results are illustrated to analyze the trend of the average buffer content for the model under consideration. It is interesting to note that the stationary solution of a ﬂuid queue driven by a queue with chain sequence rates does not exist in the absence of exponential timer.

In this paper, we deﬁne an orthonormal basis for 2-*-inner product space and obtain some useful results. Moreover, we introduce a 2-norm on a dense subset of a 2-***-inner product space. Finally, we obtain a version of the Selberg, Buzano’s and Bessel inequality and its results in an *A*-2-inner product space.

## Abstract

We provide a Maltsev characterization of congruence distributive varieties by showing that a variety 𝓥 is congruence distributive if and only if the congruence identity *k* factors) holds in 𝓥, for some natural number *k*.

## Abstract

Fix 2 < n < ω and let CA_{n} denote the class of cyindric algebras of dimension n. Roughly CA_{n} is the algebraic counterpart of the proof theory of first order logic restricted to the first *n* variables which we denote by L_{n}. The variety RCA_{n} of representable CA_{n}s reflects algebraically the semantics of *L*
_{n}. Members of RCA_{n} are concrete algebras consisting of genuine n-ary relations, with set theoretic operations induced by the nature of relations, such as projections referred to as cylindrifications. Although CA_{n} has a finite equational axiomatization, RCA_{n} is not finitely axiomatizable, and it generally exhibits wild, often unpredictable and unruly behavior. This makes the theory of CA_{n} substantially richer than that of Boolean algebras, just as much as L_{ω,ω} is richer than propositional logic. We show using a so-called blow up and blur construction that several varieties (in fact infinitely many) containing and including the variety RCA_{n} are not atom-canonical. A variety V of Boolean algebras with operators is atom canonical, if whenever **𝔄**
*L*
_{ω,ω}, fails dramatically for *L*
_{n} even if we allow certain generalized models that are only locallly clasfsical. It is also shown that any class K such that _{n} is the class of completely representable CA_{n}s, and S_{c} denotes the operation of forming dense (complete) subalgebras, is not elementary. Finally, we show that any class K such that _{d} denotes the operation of forming dense subalgebra.

## Abstract

Let **𝔄** be a unital Banach algebra and **ℜ** its Jacobson radical. This paper investigates Banach algebras satisfying some chain conditions on closed ideals. In particular, it is shown that a Banach algebra **𝔄** satisfies the descending chain condition on closed left ideals then **𝔄**/**ℜ** is finite dimensional. We also prove that a *C*
^{*}-algebra satisfies the ascending chain condition on left annihilators if and only if it is finite dimensional. Moreover, other auxiliary results are established.

## Abstract

We give two new simple characterizations of the Cauchy distribution by using the Möbius and Mellin transforms. They also yield characterizations of the circular Cauchy distribution and the mixture Cauchy model.

## Abstract

In this paper we present different variants of the well-known Hermite–Hadamard inequality, in a generalized context. We consider general fractional integral operators for *h*-convex and *r*-convex functions.

## Abstract

In this study, a normalized form of regular Coulomb wave function is considered. By using the differential subordinations method due to Miller and Mocanu, we determine some conditions on the parameters such that the normalized regular Coulomb wave function is lemniscate starlike and exponential starlike in the open unit disk, respectively. In additon, by using the relationship between the regular Coulomb wave function and the Bessel function of the first kind we give some conditions for which the classical Bessel function of the first kind is lemniscate and exponential starlike in the unit disk 𝔻.

## Abstract

This survey revisits Jenő Egerváry and Otto Szász’s article of 1928 on trigonometric polynomials and simple structured matrices focussing mainly on the latter topic. In particular, we concentrate on the spectral theory for the first type of the matrices introduced in the article, which are today referred to as *k*-tridiagonal matrices, and then discuss the explosion of interest in them over the last two decades, most of which could have benefitted from the seminal article, had it not been overlooked.