arXiv subjects

Eder Kikianty

Publications and source records attributed to Eder Kikianty.

9 recordsLinked to original sources

arXiv2026

The sup-inf-completion of a Dedekind complete vector lattice

We introduce the sup-inf-completion of a Dedekind complete vector lattice, an essentially unique extension in which every nonempty subset has both a supremum and an infimum. Since this completion is not a cone, we develop the more general framework of lattice stars, which provides the natural setting for its construction. We establish the fundamental properties of the sup-inf-completion, including a universal property, a representation theorem, and a characterization of its bands and band projections. As an application, we extend the Riemann integral on Dedekind complete $f$-algebras to Type I and Type II improper integrals. We conclude by showing that power series on universally complete vector lattices may be integrated term-by-term.

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arXiv2026

The Riemann integral on Dedekind complete $f$-algebras

In this paper we develop a theory of integration for locally band preserving functions, introduced by Ercan and Wickstead, on Dedekind complete $f$-algebras. Specifically, we construct Darboux and Riemann integrals and show that they are equal. We then connect the theory of integrable functions to the theory of order differentiable functions, introduced by the third and fourth authors, by proving a Fundamental Theorem of Calculus. Furthermore, we show that a Mean Value Theorem for Integrals holds and that we can integrate by parts and substitutions.

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arXiv2025

Classical theorems from analysis for locally band preserving functions on Dedekind complete $Φ$-algebras

In this paper we explore the concept of locally band preserving functions, introduced by Ercan and Wickstead, on Dedekind complete $Φ$-algebras. Specifically, we show that all super order differentiable functions are locally band preserving. Furthermore, some foun- dational results from classical analysis are proved in this setting, such as the Intermediate Value Theorem, the Extreme Value Theorem, and the Mean Value Theorem. Moreover, we show that these generalisations can fail for functions that are not locally band pre- serving. With the goal in mind to further develop the theory of complex differentiation in Dedekind complete complex $Φ$-algebras, a complex version of the Mean Value Theorem is also provided.

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arXiv2025

L-functional analysis

Inspired by the theories of Kaplansky-Hilbert modules and probability theory in vector lattices, we generalise functional analysis by replacing the scalars $\mathbb{R}$ or $\mathbb{C}$ by a real or complex Dedekind complete unital $f$-algebra $\mathbb{L}$; such an algebra can be represented as a suitable space of continuous functions. We set up the basic theory of $\mathbb{L}$-normed and $\mathbb{L}$-Banach spaces and bounded operators between them, we discuss the $\mathbb{L}$-valued analogues of the classical $\ell^p$-spaces, and we prove the analogue of the Hahn-Banach theorem. We also discuss the basics of the theory of $\mathbb{L}$-Hilbert spaces, including projections onto convex subsets, the Riesz Representation theorem, and representing $\mathbb{L}$-Hilbert spaces as a direct sum of $\ell^2$-spaces.

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arXiv2023

On compact packings of Euclidean space with spheres of finitely many sizes

For $d\in\mathbb{N}$, a compact sphere packing of Euclidean space $\mathbb{R}^{d}$ is a set of spheres in $\mathbb{R}^{d}$ with disjoint interiors so that the contact hypergraph of the packing is the vertex scheme of a homogeneous simplicial $d$-complex that covers all of $\mathbb{R}^{d}$. We are motivated by the question: For $d,n\in\mathbb{N}$ with $d,n\geq2$, how many configurations of numbers $0<r_{0}<r_{1}<\ldots<r_{n-1}=1$ can occur as the radii of spheres in a compact sphere packing of $\mathbb{R}^{d}$ wherein there occur exactly $n$ sizes of sphere? We introduce what we call `heteroperturbative sets' of labeled triangulations of unit spheres and we discuss the existence of non-trivial examples of heteroperturbative sets. For a fixed heteroperturbative set, we discuss how a compact sphere packing may be associated to the heteroperturbative set or not. We proceed to show, for $d,n\in\mathbb{N}$ with $d,n\geq2$ and for a fixed heteroperturbative set, that the collection of all configurations of $n$ distinct positive numbers that can occur as the radii of spheres in a compact packing is finite, when taken over all compact sphere packings of $\mathbb{R}^{d}$ which have exactly $n$ sizes of sphere and which are associated to the fixed heteroperturbative set.

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arXiv2023

Angular equivalence of normed spaces

Angular equivalence is introduced and shown to be an equivalence relation among the norms on a fixed real vector space. It is a finer notion than the usual (topological) notion of norm equivalence. Angularly equivalent norms share certain geometric properties: A norm that is angularly equivalent to a uniformly convex norm is itself uniformly convex. The same is true for strict convexity. Extreme points of the unit balls of angularly equivalent norms occur on the same rays, and if one unit ball is a polyhedron so is the other. Among norms arising from inner products, two norms are angularly equivalent if and only if they are topological equivalent. But, unlike topological equivalence, angular equivalence is able to distinguish between different norms on a finite-dimensional space. In particular, no two $\ell^p$ norms on $\mathbb R^n$ are angularly equivalent.

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arXiv2022

Further results on angular equivalence of norms

Angular equivalence of norms is introduced by Kikianty and Sinnamon (2017) and is a stronger notion than the usual topological equivalence. Given two angularly equivalent norms, if one norm has a certain geometrical property, e.g. uniform convexity, then the other norm also possesses such a property. In this paper, we show further results in this direction, namely angular equivalent norms share the property of uniform non-squareness, and that angular equivalence preserves the exposed points of the unit ball. A discussion on the (equivalence of the) dual norms of angularly equivalent norms is also given, giving a partial answer to an open problem as stated in the paper by Kikianty and Sinnamon (2017).

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arXiv2019

Three geometric constants for Morrey spaces

In this paper we calculate three geometric constants, namely the von Neumann-Jordan constant, the James constant, and the Dunkl-Williams constant, for Morrey spaces and discrete Morrey spaces. These constants measure uniformly nonsquareness of the associated spaces. We obtain that the three constants are the same as those for $L^1$ and $L^\infty$ spaces.

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arXiv2017

Discrete Morrey spaces and their generalizations

We discuss discrete Morrey spaces and their generalizations, and we prove necessary and sufficient conditions for the inclusion property among these spaces through an estimate for the characteristic sequences.

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