11 results
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2. A generalization of Bohr–Mollerup's theorem for higher order convex functions: a tutorial.
- Author
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Marichal, Jean-Luc and Zenaïdi, Naïm
- Subjects
- *
CONVEX functions , *GAMMA functions , *DIFFERENCE operators , *GENERALIZATION , *FUNCTIONAL equations , *OPEN access publishing - Abstract
In its additive version, Bohr–Mollerup's remarkable theorem states that the unique (up to an additive constant) convex solution f(x) to the equation Δ f (x) = ln x on the open half-line (0 , ∞) is the log-gamma function f (x) = ln Γ (x) , where Δ denotes the classical difference operator and Γ (x) denotes the Euler gamma function. In a recently published open access book, the authors provided and illustrated a far-reaching generalization of Bohr–Mollerup's theorem by considering the functional equation Δ f (x) = g (x) , where g can be chosen from a wide and rich class of functions that have convexity or concavity properties of any order. They also showed that the solutions f(x) arising from this generalization satisfy counterparts of many properties of the log-gamma function (or equivalently, the gamma function), including analogues of Bohr–Mollerup's theorem itself, Burnside's formula, Euler's infinite product, Euler's reflection formula, Gauss' limit, Gauss' multiplication formula, Gautschi's inequality, Legendre's duplication formula, Raabe's formula, Stirling's formula, Wallis's product formula, Weierstrass' infinite product, and Wendel's inequality for the gamma function. In this paper, we review the main results of this new and intriguing theory and provide an illustrative application. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
3. Generalized Vincze's functional equations on any group in connection with the maximum functional equation.
- Author
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Sarfraz, Muhammad, Jiang, Zhou, Liu, Qi, and Li, Yongjin
- Subjects
- *
QUADRATIC equations , *FUNCTIONAL equations , *GENERALIZATION - Abstract
In this research paper, we investigate a generalization of Vincze's type functional equations involving several (up to four) unknown functions in connection with the maximum functional equation as max { ψ (x y) , ψ (x y - 1) } = ψ (x) η (y) + ψ (y) , max { ψ (x y) , ψ (x y - 1) } = ψ (x) η (y) + χ (y) , max { ψ (x y) , ψ (x y - 1) } = ϕ (x) η (y) , max { ψ (x y) , ψ (x y - 1) } = ϕ (x) η (y) + χ (y) , where G is an arbitrary group, x , y ∈ G , and ψ , η , χ , ϕ : G → R are unknown functions. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
4. Vector valued invariant means, complementability and almost constrained subspaces.
- Author
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Łukasik, Radosław
- Subjects
- *
BANACH spaces , *GENERALIZATION - Abstract
In this paper we will study a connection between some generalization of AC-subspaces, vector valued invariant λ -means and λ -complementability. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
5. Randomly r-orthogonal factorizations in bipartite graphs.
- Author
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Yuan, Yuan and Hao, Rong-Xia
- Subjects
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FACTORIZATION , *BIPARTITE graphs , *GENERALIZATION - Abstract
Let G be a graph with vertex set V(G) and edge set E(G), and let f be an integer-valued function defined on V(G). It is proved in this paper that every bipartite (0 , m f - m + 1) -graph has a (0, f)-factorization randomly r-orthogonal to n vertex-disjoint mr-subgraphs of G, which is a generalization of the known result with n = 1 given by Zhou and Wu. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
6. Graph Lipscomb's space is a generalized Hutchinson–Barnsley fractal.
- Author
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Miculescu, Radu and Mihail, Alexandru
- Subjects
- *
GENERALIZED spaces , *METRIC spaces , *SET theory , *FRACTAL dimensions , *FRACTALS , *GENERALIZATION - Abstract
Being a universal space for weight A ≥ ℵ 0 metric spaces Lipscomb's space J A has a central role in topological dimension theory. There exists a strong connection between topological dimension theory and fractal set theory since on the one hand, some classical fractals play the role of universal spaces and on the other hand the universal space J A is a generalized Hutchinson–Barnsley fractal (i.e. the attractor of a possibly infinite iterated function system). In this paper we introduce a generalization of J A , namely the concept of graph Lipscomb's space J A G associated with a graph G on the set A, and we prove that its imbedded version in l 2 (A ′) , where A ′ = A \ { z } , z being a fixed element of the set A having at least two elements, is a generalized Hutchinson–Barnsley fractal. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
7. Multivariable generalizations of bivariate means via invariance.
- Author
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Pasteczka, Paweł
- Subjects
- *
FUNCTIONAL equations , *GENERALIZATION , *MATHEMATICS - Abstract
For a given
p -variable mean M:Ip→I\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$M :I^p \rightarrow I$$\end{document} (I is a subinterval of R\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$${\mathbb {R}}$$\end{document}), following (Horwitz in J Math Anal Appl 270(2):499–518, 2002) and (Lawson and Lim in Colloq Math 113(2):191–221, 2008), we can define (under certain assumptions) its (p+1)\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$(p+1)$$\end{document}-variable β\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$\beta $$\end{document}-invariant extension as the unique solution K:Ip+1→I\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$K :I^{p+1} \rightarrow I$$\end{document} of the functional equation K(M(x2,⋯,xp+1),M(x1,x3,⋯,xp+1),⋯,M(x1,⋯,xp))=K(x1,⋯,xp+1),for allx1,⋯,xp+1∈I\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$\begin{aligned}&K\big (M(x_2,\dots ,x_{p+1}),M(x_1,x_3,\dots ,x_{p+1}),\dots ,M(x_1,\dots ,x_p)\big )\\&\quad =K(x_1,\dots ,x_{p+1}), \text { for all }x_1,\dots ,x_{p+1} \in I \end{aligned}$$\end{document}in the family of means. Applying this procedure iteratively we can obtain a mean which is defined for vectors of arbitrary lengths starting from the bivariate one. The aim of this paper is to study the properties of such extensions. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
8. On a new class of dynamic Hardy-type inequalities and some related generalizations.
- Author
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Saker, S. H., Osman, M. M., and Anderson, Douglas R.
- Subjects
- *
GENERALIZATION , *INTEGRAL inequalities - Abstract
In this paper, we establish a new class of dynamic inequalities of Hardy's type which generalize and improve some recent results given in the literature. More precisely, we prove some new Hardy-type inequalities involving many functions on time scales. Some new discrete inequalities are deduced in seeking applications. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
9. Row-summable matrices with application to generalization of Schröder's and Abel's functional equations.
- Author
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Eshkaftaki, Ali Bayati
- Subjects
- *
GENERALIZATION , *MATRICES (Mathematics) , *OPERATOR theory - Abstract
In this paper, the author discusses a generalization of Schröder's and Abel's functional equation of the form ∑ n α n (x) f (u n (x)) = g (x). In fact, using the theory of operators and infinite matrices, we show under certain conditions this equation has only a unique bounded solution f : X → R. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
10. Conditional distributivity for semi-t-operators over uninorms.
- Author
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Wang, Wei and Qin, Feng
- Subjects
- *
UTILITY theory , *CONDITIONAL expectations , *GENERALIZATION , *AGGREGATION operators - Abstract
The conditional distributivity between two different aggregation operators, which has received wide attention from the researchers, is vital for many fields, for example, utility theory, integration theory and so on. In some existing generalization, the restrictive but not completely justified condition that the values of the inner operator are less than 1. However, for a more general and reasonable setting, the values of the inner operator should be strictly bounded between 0 and 1. Therefore, the aim of this paper is to introduce and fully characterize this kind of conditional distributivity of a semi-t-operator over a uninorm. In comparison with the corresponding results obtained, there are many new solutions. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
11. Generalization of Heron's and Brahmagupta's equalities to any cyclic polygon.
- Author
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Dulio, Paolo and Laeng, Enrico
- Subjects
- *
SYMMETRIC functions , *HERONS , *GENERALIZATION , *POLYGONS , *SYMMETRY , *QUADRILATERALS - Abstract
It is well known that Heron's equality provides an explicit formula for the area of a triangle, as a symmetric function of the lengths of its edges. It has been extended by Brahmagupta to quadrilaterals inscribed in a circle (cyclic quadrilaterals). A natural problem is trying to further generalize the result to cyclic polygons with a larger number of edges. Surprisingly, this has proved to be far from simple, and no explicit solutions exist for cyclic polygons having n > 4 edges. In this paper we investigate such a problem by following a new and elementary approach, based on the idea that the simple geometry underlying Heron's and Brahmagupta's equalities hides the real players of the game. In details, we propose to focus on the dissection of the edges determined by the incircles of a suitable triangulation of the cyclic polygon, showing that this approach leads to an explicit formula for the area as a symmetric function of the lengths of these segments. We also show that such a symmetry can be rediscovered in Heron's and Brahmagupta's results, which consequently represent special cases of the provided general equality. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
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