Results 41 to 50 of about 513,304 (193)

A Version of the Hahn-Banach Theorem for R-Vector Spaces [PDF]

Sahand Communications in Mathematical Analysis
Recently, $R$-metric spaces have been introduced to generalized metric spaces. This extension is based on the construction of a new universe with interesting properties.
Azadeh Alijani, Zohreh Heydarpour, Maryam Naderi Parizi   +2 more
doaj   +1 more source

Inverse problems for semilinear elliptic PDE with a general nonlinearity a(x,u)$a(x,u)$

Transactions of the London Mathematical Society, Volume 13, Issue 1, December 2026.
Abstract This article studies the inverse problem of recovering a nonlinearity in an elliptic equation Δu+a(x,u)=0$\Delta u + a(x,u) = 0$ from boundary measurements of solutions. Previous results based on first‐order linearization achieve this under a sign condition on ∂ua(x,u)$\partial _u a(x,u)$, and results based on higher order linearization ...
David Johansson, Janne Nurminen, Mikko Salo   +2 more
wiley   +1 more source

A Theorem of Rolewicz's Type for Measurable Evolution Families in Banach Spaces [PDF]

, 2001
Let $varphi$ be a positive and non-decreasing function defined on the real half-line and ${mathcal U}$ be a strongly measurable, exponentially bounded evolution family of bounded linear operators acting on a Banach space and satisfing a certain ...
Constantin Buse, Sever S. Dragomir, Dragomir, Sever S, Buşe, Constantin   +3 more
core  

Frank separation of two convex sets and Hahn-Banach theorem [PDF]

, 1977
First we give some elementary properties of the core of a subset relative to a linear subspace. Then we prove a theorem on the frank separation of two convex sets.
Vangeldère, J
core   +1 more source

On the Existence of Solutions of Dynamic Equations on Time Scales in Banach Spaces

Mathematical Methods in the Applied Sciences, Volume 49, Issue 13, Page 15358-15384, 15 September 2026.
ABSTRACT In this paper we address the question of solvability of dynamic equations on time scales in Banach spaces. In particular, our main theorem extends the result for classical differential equations in Banach spaces of Banaś and Goebel established in [5], to an arbitrary time scale.
Dušan Oberta
wiley   +1 more source

The Hahn-Banach theorem for the normed spaces [PDF]

, 2013
It is intended, in this chapter, to present the Hahn-Banach theorem in its version for the normed spaces. This result is particularly important in optimization problems because of the separation theorems consequences of ...
Ferreira, Manuel Alberto M.
core   +1 more source

Transversal functional analysis [PDF]

Mathematica Moravica, 2014
This paper provides an introduction to the ideas and methods of transversal functional analysis based on the transversal sets theory. A unifying concept that lies at the heart of transversal functional analysis is that of a transversal normed linear ...
Tasković Milan R.
doaj  

Amenability Constants for Unconditional Sums of Banach Algebras

Mathematische Nachrichten, Volume 299, Issue 9, Page 2472-2494, September 2026.
ABSTRACT We study Johnson amenability for unconditional direct sums of Banach algebras. Given a family (Ai)i∈I$(A_i)_{i\in I}$ of Banach algebras and a Banach sequence lattice E$E$ on I$I$, the E$E$‐sum ⨁i∈IAiE${\bigl (\bigoplus _{i\in I} A_i\bigr)}_{\!E}$ carries a natural Banach algebra structure via coordinatewise multiplication.
Tomasz Kania, Jerzy Ka̧kol
wiley   +1 more source

Null projections and noncommutative function theory in operator algebras

Journal of the London Mathematical Society, Volume 114, Issue 1, July 2026.
Abstract We study projections in the bidual of a C∗$\mathrm{C}^*$‐algebra B$B$ that are null with respect to a subalgebra A$A$, that is, projections p∈B∗∗$p\in B^{**}$ satisfying |φ|(p)=0$|\varphi |(p)=0$ for every φ∈B∗$\varphi \in B^*$ annihilating A$A$. In the separable case, A$A$‐null projections are precisely the peak projections in the bidual of A$
David P. Blecher, Raphaël Clouâtre
wiley   +1 more source

KKM implies Hahn-Banach

Results in Nonlinear Analysis, 2019
Our title means that the Knaster-Kuratowski Mazurkiewicz theorem in 1929 implies the Hahn-Banach theorem. This theorem originated from Hahn in 1926 and Banach in 1929 is of basic importance in the analysis of problems concerning the existence of ...
Sehie Park
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