Browse Our Mathematics and Statistics Journals

**Mathematics and statistics journals publish papers on the theory and application of mathematics, statistics, and probability. Most mathematics journals have a broad scope that encompasses most mathematical fields. These commonly include logic and foundations, algebra and number theory, analysis (including differential equations, functional analysis and operator theory), geometry, topology, combinatorics, probability and statistics, numerical analysis and computation theory, mathematical physics, etc.**

# Mathematics and Statistics

*ɣ*and Φ

_{1}be nondecreasing and nonnegative functions defined on [0, ∞), and Φ

_{2}is an

*N*-function,

*u, v*and

*w*are weights. A unified version of weighted weak type inequality of the form

for martingale maximal operators *f*
^{∗} is considered, some necessary and su@cient conditions for it to hold are shown. In addition, we give a complete characterization of three-weight weak type maximal inequality of martingales. Our results generalize some known results on weighted theory of martingale maximal operators.

This paper is concerned with the existence of weak solutions for obstacle problems. By means of the Young measure theory and a theorem of Kinderlehrer and Stampacchia, we obtain the needed result.

During the last decade, a number of explicit results about the distributions of exponential functionals of Brownian motion with drift:

In the present paper, we rely extensively on these results to show the existence of limiting measures as

Although a large number of similar studies have been made for, say, one-dimensional diffusions, the present study, which focuses upon Brownian exponential functionals, appears to be new.

We study the effect on sections of a soluble-by-finite group *G* of finite rank of an almost fixed-point-free automorphism *φ* of *G* of finite order. We also elucidate the structure of *G* if *φ* has order 4 and if *G* is also (torsion-free)-by-finite. The latter extends recent work of Xu, Zhou and Liu.

In this paper, we investigate the uniqueness of algebroid functions in angular domain by the method of conformal mapping. We discuss the relations between the Borel directions and uniquenss with the multiple values of algebroid functions and obtain some results which extend some uniqueness results of meromorphic functions to that of algebroid functions.

The paper provides a detailed study of inequalities of complete moduli of smoothness of functions with transformed Fourier series by moduli of smoothness of initial functions. Upper and lower estimates of the norms and best approximations of the functions with transformed Fourier series by the best approximations of initial functions are also obtained.

Let *N* be a sufficiently large integer. In this paper, it is proved that, with at most *O*(*N*
^{119/270+}
*
^{s}
*) exceptions, all even positive integers up to

*N*can be represented in the form

where *p*
_{1}
*, p*
_{2}
*, p*
_{3}
*, p*
_{4}
*, p*
_{5}
*, p*
_{6} are prime numbers.

This paper is concerned with the existence of solutions to a class of p(x)-Kirchhoff-type equations with Robin boundary data as follows:

Where

The major aim of the note is to give new brief proofs of the results in the paper “The influence of weakly *H* -subgroups on the structure of finite groups” [Studia Scientiarum Mathematicarum Hungarica, 51 (1), 27–40 (2014)].

In this paper we prove and discuss some new (H_{p}, L_{p,∞}) type inequalities of the maximal operators of T means with monotone coefficients with respect to Walsh–Kaczmarz system. It is also proved that these results are the best possible in a special sense. As applications, both some well-known and new results are pointed out. In particular, we apply these results to prove a.e. convergence of such T means.

The sticky polymatroid conjecture states that any two extensions of the polymatroid have an amalgam if and only if the polymatroid has no non-modular pairs of flats. We show that the conjecture holds for polymatroids on five or less elements.

A linear operator on a Hilbert space *S* is shown to be densely defined and closed if and only if

In a more general setup, we can consider relations instead of operators and we prove that in this situation a similar result holds. We give a necessary and sufficient condition for a linear relation to be densely defined and self-adjoint.

Let *X* be a topological space. For any positive integer *n*, we consider the *n*-fold symmetric product of *X*, ℱ*
_{n}
*(

*X*), consisting of all nonempty subsets of

*X*with at most

*n*points; and for a given function

*ƒ*:

*X*→

*X*, we consider the induced functions ℱ

*(*

_{n}*ƒ*): ℱ

*(*

_{n}*X*) → ℱ

*(*

_{n}*X*). Let

*M*be one of the following classes of functions: exact, transitive, ℤ-transitive, ℤ

_{+}-transitive, mixing, weakly mixing, chaotic, turbulent, strongly transitive, totally transitive, orbit-transitive, strictly orbit-transitive, ω-transitive, minimal,

*I N, T T*

_{++}, semi-open and irreducible. In this paper we study the relationship between the following statements:

*ƒ*∈

*M*and ℱ

*(*

_{n}*ƒ*) ∈

*M*.

Infinite matroids have been defined by Reinhard Diestel and coauthors in such a way that this class is (together with the finite matroids) closed under dualization and taking minors. On the other hand, Andreas Dress introduced a theory of matroids with coefficients in a fuzzy ring which is – from a combinatorial point of view – less general, because within this theory every circuit has a finite intersection with every cocircuit. Within the present paper, we extend the theory of matroids with coefficients to more general classes of matroids, if the underlying fuzzy ring has certain properties to be specified.

In many clique search algorithms well coloring of the nodes is employed to find an upper bound of the clique number of the given graph. In an earlier work a non-traditional edge coloring scheme was proposed to get upper bounds that are typically better than the one provided by the well coloring of the nodes. In this paper we will show that the same scheme for well coloring of the edges can be used to find lower bounds for the clique number of the given graph. In order to assess the performance of the procedure we carried out numerical experiments.

This paper solves an enumerative problem which arises naturally in the context of Pascal’s hexagram. We prove that a general Desargues configuration in the plane is associated to *six* conical sextuples via the theorems of Pascal and Kirkman. Moreover, the Galois group associated to this problem is isomorphic to the symmetric group on six letters.

The purpose of this paper is to study the principal fibre bundle (*P*, *M*, *G*, *π*
_{
p
} ) with Lie group *G*, where M admits Lorentzian almost paracontact structure (*Ø*, *ξ*
_{
p
}, η_{
p
}, *g*) satisfying certain condtions on (1, 1) tensor field *J*, indeed possesses an almost product structure on the principal fibre bundle. In the later sections, we have defined trilinear frame bundle and have proved that the trilinear frame bundle is the principal bundle and have proved in Theorem 5.1 that the Jacobian map *π*
^{
*
} is the isomorphism.

Many combinatorial optimization problems can be expressed in terms of zero-one linear programs. For the maximum clique problem the so-called edge reformulation is applied most commonly. Two less frequently used LP equivalents are the independent set and edge covering set reformulations. The number of the constraints (as a function of the number of vertices of the ground graph) is asymptotically quadratic in the edge and the edge covering set LP reformulations and it is exponential in the independent set reformulation, respectively. F. D. Croce and R. Tadei proposed an approach in which the number of the constraints is equal to the number of the vertices. In this paper we are looking for possible tighter variants of these linear programs.

We introduce the directional short-time Fourier transform for which we prove a new Plancherel’s formula. We also prove for this transform several uncertainty principles as Heisenberg inequalities, logarithmic uncertainty principle, Faris–Price uncertainty principles and Donoho–Stark’s uncertainty principles.

We deﬁne the extended beta family of distributions to generalize the beta generator pioneered by Eugene *et al*. [10]. This paper is cited in at least 970 scientiﬁc articles and extends more than ﬁfty well-known distributions. Any continuous distribution can be generalized by means of this family. The proposed family can present greater ﬂexibility to model skewed data. Some of its mathematical properties are investigated and maximum likelihood is adopted to estimate its parameters. Further, for different parameter settings and sample sizes, some simulations are conducted. The superiority of the proposed family is illustrated by means of two real data sets.

We present the sufficient condition for a classical two-class problem from Fisher discriminant analysis has a solution. Actually, the solution was presented up to our knowledge with a necessary condition only. We use an extended Cauchy–Schwarz inequality as a tool.

Let be a Schrödinger operator on the Heisenberg group *V* belongs to the reverse Hölder class

where

and

Where

Based on this inequality and known results for the Lusin area integral *V*, the author establishes the boundedness properties of the operator

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

*is the algebraic counterpart of the proof theory of first order logic restricted to the first*

_{n}*n*variables which we denote by

*L*. The variety RCA

_{n}*of representable CA*

_{n}*s reflects algebraically the semantics of*

_{n}*L*. Members of RCA

_{n}*are concrete algebras consisting of genuine*

_{n}*n*-ary relations, with set theoretic operations induced by the nature of relations, such as projections referred to as cylindrifications. Although CA

*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*

_{n}*L*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

_{ω,ω}*are not atom-canonical. A variety V of Boolean algebras with operators is atom canonical, if whenever*

_{n}*L*, fails dramatically for

_{ω,ω}*L*even if we allow certain generalized models that are only locallly classical. It is also shown that any class K such that Nr

_{n}*CA*

_{n}*∩ CRCA*

_{ω}

_{n}**S**

*Nr*

_{c}*CA*

_{n}

_{n}_{+3}, where CRCA

*is the class of completely representable CA*

_{n}*s, and*

_{n}**S**

*denotes the operation of forming dense (complete) subalgebras, is not elementary. Finally, we show that any class K such that*

_{c}**S**

*RaCA*

_{d}

_{ω}**S**

*RaCA*

_{c}_{5}is not elementary, where

**S**

*denotes the operation of forming dense subalgebra.*

_{d}## 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.

## Abstract

Let *K* = ℚ(*α*) be a number field generated by a complex root *α* of a monic irreducible polynomial *f*(*x*) = *x*
^{24} – *m*, with *m* ≠ 1 is a square free rational integer. In this paper, we prove that if *m* ≡ 2 or 3 (mod 4) and *m* ≢∓1 (mod 9), then the number field *K* is monogenic. If *m* ≡ 1 (mod 4) or *m* ≡ 1 (mod 9), then the number field *K* is not monogenic.

## Abstract

In this study, we investigate suborbital graphs *G*
_{
u,n
} of the normalizer Γ_{
B
} (*N*) of Γ_{0} (*N*) in *PSL*(2, ℝ) for *N* = 2^{
α
}3^{
β
} where *α* = 1, 3, 5, 7, and *β* = 0 or 2. In these cases the normalizer becomes a triangle group and graphs arising from the action of the normalizer contain quadrilateral circuits. In order to obtain graphs, we first define an imprimitive action of Γ_{
B
} (*N*) on *N*) and then obtain some properties of the graphs arising from this action.

## Abstract

*n,m*≥ 2 this paper is devoted to the description of the sets of extreme and exposed points of the closed unit balls of

*n*-linear forms on

*n*-linear forms. First we classify the extreme points of the unit balls of

and

which answers the questions in [31].

## Abstract

Consider the sequence *s* of the signs of the coefficients of a real univariate polynomial *P* of degree *d*. Descartes’ rule of signs gives compatibility conditions between *s* and the pair (*r*
^{+}
*,r*
^{−}), where *r*
^{+} is the number of positive roots and *r*
^{−} the number of negative roots of *P*. It was recently asked if there are other compatibility conditions, and the answer was given in the form of a list of incompatible triples (*s*; *r*
^{+}
*,r*
^{−}) which begins at degree *d* = 4 and is known up to degree 8. In this paper we raise the question of the compatibility conditions for *i*-th derivative of *P*. We prove that up to degree 5, there are no other compatibility conditions than the Descartes conditions, the above recent incompatibilities for each *i*, and the trivial conditions given by Rolle’s theorem.

## Abstract

Let *l,m,r* be fixed positive integers such that 2*l*, 3*lm*, *l > r* and 3 | *r*. In this paper, using the BHV theorem on the existence of primitive divisors of Lehmer numbers, we prove that if min{*rlm*
^{2} − 1*,*(*l* − *r*)*lm*
^{2} + 1} *>* 30, then the equation (*rlm*
^{2} − 1)^{
x
} + ((*l* − *r*)*lm*
^{2} + 1)^{
y
} = (*lm*)^{
z
} has only the positive integer solution (*x,y,z*) = (1*,*1*,*2).

## Abstract

In 1975 C. F. Chen and C. H. Hsiao established a new procedure to solve initial value problems of systems of linear differential equations with constant coefficients by Walsh polynomials approach. However, they did not deal with the analysis of the proposed numerical solution. In a previous article we study this procedure in case of one equation with the techniques that the theory of dyadic harmonic analysis provides us. In this paper we extend these results through the introduction of a new procedure to solve initial value problems of differential equations with not necessarily constant coefficients.

## Abstract

Let *n*. Further, let*p*(*z*) ≡ *z*
^{
n
}
*p*(1*/z*). In this paper we obtain some inequalites in this direction for polynomials that belong to this class and have all their coefficients in any sector of opening *γ*, where 0 *γ < π*. Our results generalize and sharpen several of the known results in this direction, including those of Govil and Vetterlein [3], and Rahman and Tariq [12]. We also present two examples to show that in some cases the bounds obtained by our results can be considerably sharper than the known bounds.

## Abstract

In this paper, we prove that if *X* is a space with a regular *G*
_{
δ
}-diagonal and *X*
^{2} is star Lindelöf then the cardinality of *X* is at most 2^{c}. We also prove that if *X* is a star Lindelöf space with a symmetric *g*-function such that *g*
^{2}(*n, x*): *n* ∈ *ω*} = {*x*} for each *x* ∈ *X* then the cardinality of *X* is at most 2^{c}. Moreover, we prove that if *X* is a star Lindelöf Hausdorff space satisfying *Hψ*(*X*) = *κ* then *e*(*X*) ^{2κ
}; and if *X* is Hausdorff and *we*(*X*) = *Hψ*(*X*) = *κ*subset of a space then *e*(*X*) ^{
κ
}. Finally, we prove that under *V* = *L* if *X* is a first countable DCCC normal space then *X* has countable extent; and under MA+¬CH there is an example of a first countable, DCCC and normal space which is not star countable extent. This gives an answer to the Question 3.10 in *Spaces with property* (*DC*(*ω*
_{1})), *Comment. Math. Univ. Carolin.*, **58(1)** (2017), 131-135.

## Abstract

Fejes Tóth [3] studied approximations of smooth surfaces in three-space by piecewise flat triangular meshes with a given number of vertices on the surface that are optimal with respect to Hausdorff distance. He proves that this Hausdorff distance decreases inversely proportional with the number of vertices of the approximating mesh if the surface is convex. He also claims that this Hausdorff distance is inversely proportional to the *square* of the number of vertices for a specific non-convex surface, namely a one-sheeted hyperboloid of revolution bounded by two congruent circles. We refute this claim, and show that the asymptotic behavior of the Hausdorff distance is linear, that is the same as for convex surfaces.

## Abstract

Let *H*
_{
n
} be the *n*-th harmonic number and let *v*
_{
n
} be its denominator. It is known that *v*
_{
n
} is even for every integer *H*
_{
n
} and prove that for any integer *n*, *v*
_{
n
} = *e*
^{
n(1+o(1))}. In addition, we obtain some results of the logarithmic density of harmonic numbers.

## Abstract

We verify an upper bound of Pach and Tóth from 1997 on the midrange crossing constant. Details of their

## Abstract

Let 0 *< γ*
_{1}
*< γ*
_{2}
*<* ··· ⩽ ··· be the imaginary parts of non-trivial zeros of the Riemann zeta-function. In the paper, we consider the approximation of analytic functions by shifts of the Hurwitz zeta-function *ζ*(*s* + *iγ*
_{
k
}
*h, α*), *h >* 0, with parameter *α* such that the set {log(*m* + *α*): *m* ∈ *γ*
_{
k
}} is applied.

## Abstract

We study certain subgroups of the full group of Hopf algebra automorphisms of twisted tensor biproducts.

## Abstract

In this paper, we obtain generalized weighted Sobolev-Morrey estimates with weights from the Muckenhoupt class *A _{p}
* by establishing boundedness of several important operators in harmonic analysis such as Hardy-Littlewood operators and Calderon-Zygmund singular integral operators in generalized weighted Morrey spaces. As a consequence, a priori estimates for the weak solutions Dirichlet boundary problem uniformly elliptic equations of higher order in generalized weighted Sobolev-Morrey spaces in a smooth bounded domain Ω ⊂ ℝ

*are obtained.*

^{n}## Abstract

Let *X* be a Hilbert *C**-module over a *C**-algebra *B*. In this paper we introduce two classes of operator algebras on the Hilbert *C**-module *X* called operator algebras with property *B* and *X*. Some of our results generalize the previous results. Also we investigate some properties of these classes of operator algebras.

## Abstract

Let *m* ≠ 0, ±1 and *n* ≥ 2 be integers. The ring of algebraic integers of the pure fields of type *n* = 2, 3,4. It is well known that for *n* = 2, an integral basis of the pure quadratic fields can be given parametrically, by using the remainder of the square-free part of m modulo 4. Such characterisation of an integral basis also exists for cubic and quartic pure fields, but for higher degree pure fields there are only results for special cases.

In this paper we explicitly give an integral basis of the field *n*.