Applications of Inequalities and Functional Analysis

A special issue of Mathematics (ISSN 2227-7390). This special issue belongs to the section "Engineering Mathematics".

Deadline for manuscript submissions: closed (31 May 2021) | Viewed by 30054

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Guest Editor
Department of Mathematics and Informatics, Lucian Blaga University of Sibiu, 550012 Sibiu, Romania
Interests: approximation theory; numerical analysis; probability and statistics
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The study of inequalities itself is a vast subject which has a huge number of applications in mathematics, physics, and engineering. Strong connections of this theory have been revealed with other fields such as functional analysis, approximation theory, probability theory and information theory. The impact of this field will grow even more in the future because of its impact in applied mathematics.

The aim of this themed issue is to report recent research results on inequalities and their applications in approximation theory and functional analysis, carry out interactions among researchers, discuss important research problems and directions, and promote these methods in various research areas. We would like to invite new findings on the areas cited above, or nearby.

Topics Covered:

Functional Analysis;
Inequalities;
Approximation theory;
Numerical analysis;
Information theory.

Prof. Ana-Maria Acu
Guest Editor

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Published Papers (15 papers)

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Research

17 pages, 4724 KiB  
Article
Nonlinear Mixed Convective Flow over a Moving Yawed Cylinder Driven by Buoyancy
by Prabhugouda M. Patil, Hadapad F. Shankar and Mikhail A. Sheremet
Mathematics 2021, 9(11), 1275; https://doi.org/10.3390/math9111275 - 01 Jun 2021
Cited by 16 | Viewed by 2349
Abstract
The fluid flow over a yawed cylinder is useful in understanding practical significance for undersea applications, for example, managing transference and/or separation of the boundary layer above submerged blocks and in suppressing recirculating bubbles. The present analysis examines nonlinear mixed convection flow past [...] Read more.
The fluid flow over a yawed cylinder is useful in understanding practical significance for undersea applications, for example, managing transference and/or separation of the boundary layer above submerged blocks and in suppressing recirculating bubbles. The present analysis examines nonlinear mixed convection flow past a moving yawed cylinder with diffusion of liquid hydrogen. The coupled nonlinear control relations and the border restrictions pertinent to the present flow problem are nondimensionalized by using nonsimilar reduction. Further, implicit finite difference schemes and Quasilinearization methods are employed to solve the nondimensional governing equations. Impact of several nondimensional parameters of the analysis on the dimensionless velocity, temperature and species concentration patterns and also on Nusselt number, Sherwood number and friction parameter defined at the cylinder shell is analyzed through numerical results presented in various graphs. Velocity profiles can be enhanced, and the coefficients of friction at the surface can be reduced, for increasing values of velocity ratio parameters along chordwise as well as spanwise directions. Species concentration profile is reduced, while the Sherwood number is enhanced, for growth of the Schmidt number and yaw angles. Furthermore, for an increasing value of yaw angle, skin-friction coefficient in chordwise direction diminishes in opposing buoyancy flow case, whereas the results exhibit the opposite trend in assisting buoyancy flow case. Moreover, very importantly, for increasing magnitude of nonlinear convection characteristic, the liquid velocity and surface friction enhance in spanwise direction. Further, for increasing magnitude of combined convection characteristics, velocity profiles and coefficient of friction at the surface enhance in both spanwise and chordwise directions. Moreover, we have observed that there is no deviation for zero yaw angle in Nusselt number and Sherwood number. Full article
(This article belongs to the Special Issue Applications of Inequalities and Functional Analysis)
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10 pages, 247 KiB  
Article
A New Algebraic Inequality and Some Applications in Submanifold Theory
by Ion Mihai and Radu-Ioan Mihai
Mathematics 2021, 9(11), 1175; https://doi.org/10.3390/math9111175 - 23 May 2021
Cited by 2 | Viewed by 1237
Abstract
We give a simple proof of the Chen inequality involving the Chen invariant δ(k) of submanifolds in Riemannian space forms. We derive Chen’s first inequality and the Chen–Ricci inequality. Additionally, we establish a corresponding inequality for statistical submanifolds. Full article
(This article belongs to the Special Issue Applications of Inequalities and Functional Analysis)
18 pages, 381 KiB  
Article
Inequalities for Information Potentials and Entropies
by Ana Maria Acu, Alexandra Măduţa, Diana Otrocol and Ioan Raşa
Mathematics 2020, 8(11), 2056; https://doi.org/10.3390/math8112056 - 18 Nov 2020
Cited by 2 | Viewed by 1425
Abstract
We consider a probability distribution p0(x),p1(x), depending on a real parameter x. The associated information potential is [...] Read more.
We consider a probability distribution p0(x),p1(x), depending on a real parameter x. The associated information potential is S(x):=kpk2(x). The Rényi entropy and the Tsallis entropy of order 2 can be expressed as R(x)=logS(x) and T(x)=1S(x). We establish recurrence relations, inequalities and bounds for S(x), which lead immediately to similar relations, inequalities and bounds for the two entropies. We show that some sequences Rn(x)n0 and Tn(x)n0, associated with sequences of classical positive linear operators, are concave and increasing. Two conjectures are formulated involving the information potentials associated with the Durrmeyer density of probability, respectively the Bleimann–Butzer–Hahn probability distribution. Full article
(This article belongs to the Special Issue Applications of Inequalities and Functional Analysis)
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11 pages, 320 KiB  
Article
On an Inequality for Legendre Polynomials
by Florin Sofonea and Ioan Ţincu
Mathematics 2020, 8(11), 2044; https://doi.org/10.3390/math8112044 - 17 Nov 2020
Cited by 2 | Viewed by 1883
Abstract
This paper is concerned with the orthogonal polynomials. Upper and lower bounds of Legendre polynomials are obtained. Furthermore, entropies associated with discrete probability distributions is a topic considered in this paper. Bounds of the entropies which improve some previously known results are obtained [...] Read more.
This paper is concerned with the orthogonal polynomials. Upper and lower bounds of Legendre polynomials are obtained. Furthermore, entropies associated with discrete probability distributions is a topic considered in this paper. Bounds of the entropies which improve some previously known results are obtained in terms of inequalities. In order to illustrate the results obtained in this paper and to compare them with other results from the literature some graphs are provided. Full article
(This article belongs to the Special Issue Applications of Inequalities and Functional Analysis)
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21 pages, 1901 KiB  
Article
Bijective Mapping Analysis to Extend the Theory of Functional Connections to Non-Rectangular 2-Dimensional Domains
by Daniele Mortari and David Arnas
Mathematics 2020, 8(9), 1593; https://doi.org/10.3390/math8091593 - 16 Sep 2020
Cited by 7 | Viewed by 2711
Abstract
This work presents an initial analysis of using bijective mappings to extend the Theory of Functional Connections to non-rectangular two-dimensional domains. Specifically, this manuscript proposes three different mappings techniques: (a) complex mapping, (b) the projection mapping, and (c) polynomial mapping. In that respect, [...] Read more.
This work presents an initial analysis of using bijective mappings to extend the Theory of Functional Connections to non-rectangular two-dimensional domains. Specifically, this manuscript proposes three different mappings techniques: (a) complex mapping, (b) the projection mapping, and (c) polynomial mapping. In that respect, an accurate least-squares approximated inverse mapping is also developed for those mappings with no closed-form inverse. Advantages and disadvantages of using these mappings are highlighted and a few examples are provided. Additionally, the paper shows how to replace boundary constraints expressed in terms of a piece-wise sequence of functions with a single function, which is compatible and required by the Theory of Functional Connections already developed for rectangular domains. Full article
(This article belongs to the Special Issue Applications of Inequalities and Functional Analysis)
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10 pages, 220 KiB  
Article
Simpson’s Rule and Hermite–Hadamard Inequality for Non-Convex Functions
by Slavko Simić and Bandar Bin-Mohsin
Mathematics 2020, 8(8), 1248; https://doi.org/10.3390/math8081248 - 31 Jul 2020
Cited by 3 | Viewed by 1532
Abstract
In this article we give a variant of the Hermite–Hadamard integral inequality for twice differentiable functions. It represents an improvement of this inequality in the case of convex/concave functions. Sharp two-sided inequalities for Simpson’s rule are also proven along with several extensions. Full article
(This article belongs to the Special Issue Applications of Inequalities and Functional Analysis)
9 pages, 251 KiB  
Article
Some Properties of Extended Euler’s Function and Extended Dedekind’s Function
by Nicuşor Minculete and Diana Savin
Mathematics 2020, 8(8), 1222; https://doi.org/10.3390/math8081222 - 25 Jul 2020
Cited by 2 | Viewed by 1842
Abstract
In this paper, we find some properties of Euler’s function and Dedekind’s function. We also generalize these results, from an algebraic point of view, for extended Euler’s function and extended Dedekind’s function, in algebraic number fields. Additionally, some known inequalities involving Euler’s function [...] Read more.
In this paper, we find some properties of Euler’s function and Dedekind’s function. We also generalize these results, from an algebraic point of view, for extended Euler’s function and extended Dedekind’s function, in algebraic number fields. Additionally, some known inequalities involving Euler’s function and Dedekind’s function, we generalize them for extended Euler’s function and extended Dedekind’s function, working in a ring of integers of algebraic number fields. Full article
(This article belongs to the Special Issue Applications of Inequalities and Functional Analysis)
14 pages, 255 KiB  
Article
A New Extension of Hardy-Hilbert’s Inequality Containing Kernel of Double Power Functions
by Bicheng Yang, Shanhe Wu and Qiang Chen
Mathematics 2020, 8(6), 894; https://doi.org/10.3390/math8060894 - 02 Jun 2020
Cited by 14 | Viewed by 1432
Abstract
In this paper, we provide a new extension of Hardy-Hilbert’s inequality with the kernel consisting of double power functions and derive its equivalent forms. The obtained inequalities are then further discussed regarding the equivalent statements of the best possible constant factor related to [...] Read more.
In this paper, we provide a new extension of Hardy-Hilbert’s inequality with the kernel consisting of double power functions and derive its equivalent forms. The obtained inequalities are then further discussed regarding the equivalent statements of the best possible constant factor related to several parameters. The operator expressions of the extended Hardy-Hilbert’s inequality are also considered. Full article
(This article belongs to the Special Issue Applications of Inequalities and Functional Analysis)
12 pages, 268 KiB  
Article
Convergence of Generalized Lupaş-Durrmeyer Operators
by Mohd Qasim, Mohammad Mursaleen, Asif Khan and Zaheer Abbas
Mathematics 2020, 8(5), 852; https://doi.org/10.3390/math8050852 - 24 May 2020
Cited by 1 | Viewed by 2379
Abstract
The main aim of this paper is to establish summation-integral type generalized Lupaş operators with weights of Beta basis functions which depends on μ having some properties. Primarily, for these new operators, we calculate moments and central moments, weighted approximation is discussed. Further, [...] Read more.
The main aim of this paper is to establish summation-integral type generalized Lupaş operators with weights of Beta basis functions which depends on μ having some properties. Primarily, for these new operators, we calculate moments and central moments, weighted approximation is discussed. Further, Voronovskaya type asymptotic theorem is proved. Finally, quantitative estimates for the local approximation is taken into consideration. Full article
(This article belongs to the Special Issue Applications of Inequalities and Functional Analysis)
12 pages, 282 KiB  
Article
Estimates for the Differences of Certain Positive Linear Operators
by Ana Maria Acu, Sever Hodiş and Ioan Rașa
Mathematics 2020, 8(5), 798; https://doi.org/10.3390/math8050798 - 14 May 2020
Cited by 9 | Viewed by 1682
Abstract
The present paper deals with estimates for differences of certain positive linear operators defined on bounded or unbounded intervals. Our approach involves Baskakov type operators, the kth order Kantorovich modification of the Baskakov operators, the discrete operators associated with Baskakov operators, Meyer–König [...] Read more.
The present paper deals with estimates for differences of certain positive linear operators defined on bounded or unbounded intervals. Our approach involves Baskakov type operators, the kth order Kantorovich modification of the Baskakov operators, the discrete operators associated with Baskakov operators, Meyer–König and Zeller operators and Bleimann–Butzer–Hahn operators. Furthermore, the estimates in quantitative form of the differences of Baskakov operators and their derivatives in terms of first modulus of continuity are obtained. Full article
(This article belongs to the Special Issue Applications of Inequalities and Functional Analysis)
7 pages, 248 KiB  
Communication
Absolute Continuity of Fuzzy Measures and Convergence of Sequence of Measurable Functions
by Jun Li
Mathematics 2020, 8(5), 726; https://doi.org/10.3390/math8050726 - 05 May 2020
Viewed by 1629
Abstract
In this note, the convergence of the sum of two convergent sequences of measurable functions is studied by means of two types of absolute continuity of fuzzy measures, i.e., strong absolute continuity of Type I, and Type VI. The discussions of convergence a.e. [...] Read more.
In this note, the convergence of the sum of two convergent sequences of measurable functions is studied by means of two types of absolute continuity of fuzzy measures, i.e., strong absolute continuity of Type I, and Type VI. The discussions of convergence a.e. and convergence in measure are done in the general framework relating to a pair of monotone measures, and general results are shown. The previous related results are generalized. Full article
(This article belongs to the Special Issue Applications of Inequalities and Functional Analysis)
13 pages, 322 KiB  
Article
Inertial Krasnoselskii–Mann Method in Banach Spaces
by Yekini Shehu and Aviv Gibali
Mathematics 2020, 8(4), 638; https://doi.org/10.3390/math8040638 - 21 Apr 2020
Cited by 6 | Viewed by 2437
Abstract
In this paper, we give a general inertial Krasnoselskii–Mann algorithm for solving inclusion problems in Banach Spaces. First, we establish a weak convergence in real uniformly convex and q-uniformly smooth Banach spaces for finding fixed points of nonexpansive mappings. Then, a strong [...] Read more.
In this paper, we give a general inertial Krasnoselskii–Mann algorithm for solving inclusion problems in Banach Spaces. First, we establish a weak convergence in real uniformly convex and q-uniformly smooth Banach spaces for finding fixed points of nonexpansive mappings. Then, a strong convergence is obtained for the inertial generalized forward-backward splitting method for the inclusion. Our results extend many recent and related results obtained in real Hilbert spaces. Full article
(This article belongs to the Special Issue Applications of Inequalities and Functional Analysis)
12 pages, 267 KiB  
Article
About Aczél Inequality and Some Bounds for Several Statistical Indicators
by Augusta Raţiu and Nicuşor Minculete
Mathematics 2020, 8(4), 574; https://doi.org/10.3390/math8040574 - 13 Apr 2020
Cited by 1 | Viewed by 1708
Abstract
In this paper, we will study a refinement of the Cauchy–Buniakowski–Schwarz inequality and a refinement of the Aczél inequality by the technique of the monotony of a sequence. In the final part, we present some properties of bounds of several statistical indicators of [...] Read more.
In this paper, we will study a refinement of the Cauchy–Buniakowski–Schwarz inequality and a refinement of the Aczél inequality by the technique of the monotony of a sequence. In the final part, we present some properties of bounds of several statistical indicators of variation. Full article
(This article belongs to the Special Issue Applications of Inequalities and Functional Analysis)
17 pages, 320 KiB  
Article
Generalized Integral Transforms via the Series Expressions
by Hyun Soo Chung
Mathematics 2020, 8(4), 539; https://doi.org/10.3390/math8040539 - 06 Apr 2020
Cited by 7 | Viewed by 1632
Abstract
From the change of variable formula on the Wiener space, we calculate various integral transforms for functionals on the Wiener space. However, not all functionals can be obtained by using this formula. In the process of calculating the integral transform introduced by Lee, [...] Read more.
From the change of variable formula on the Wiener space, we calculate various integral transforms for functionals on the Wiener space. However, not all functionals can be obtained by using this formula. In the process of calculating the integral transform introduced by Lee, this formula is also used, but it is also not possible to calculate for all the functionals. In this paper, we define a generalized integral transform. We then introduce a new method to evaluate the generalized integral transform for functionals using series expressions. Our method can be used to evaluate various functionals that cannot be calculated by conventional methods. Full article
(This article belongs to the Special Issue Applications of Inequalities and Functional Analysis)
14 pages, 286 KiB  
Article
Short Remarks on Complete Monotonicity of Some Functions
by Ladislav Matejíčka
Mathematics 2020, 8(4), 537; https://doi.org/10.3390/math8040537 - 05 Apr 2020
Cited by 2 | Viewed by 2181
Abstract
In this paper, we show that the functions x m | β ( m ) ( x ) | are not completely monotonic on ( 0 , ) for all m N , where β ( x ) is the Nielsen’s [...] Read more.
In this paper, we show that the functions x m | β ( m ) ( x ) | are not completely monotonic on ( 0 , ) for all m N , where β ( x ) is the Nielsen’s β -function and we prove the functions x m 1 | β ( m ) ( x ) | and x m 1 | ψ ( m ) ( x ) | are completely monotonic on ( 0 , ) for all m N , m > 2 , where ψ ( x ) denotes the logarithmic derivative of Euler’s gamma function. Full article
(This article belongs to the Special Issue Applications of Inequalities and Functional Analysis)
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