Nonlinear Fenchel Conjugates

Fuente: arXiv
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Hauptverfasser: Schiela, Anton, Herzog, Roland, Bergmann, Ronny
Format: Preprint
Veröffentlicht: 2024
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author Schiela, Anton
Herzog, Roland
Bergmann, Ronny
author_facet Schiela, Anton
Herzog, Roland
Bergmann, Ronny
contents The classical concept of Fenchel conjugation is tailored to extended real-valued functions defined on linear spaces. In this paper we generalize this concept to functions defined on arbitrary sets that do not necessarily bear any structure at all. This generalization is obtained by replacing linear test functions by general nonlinear ones. Thus, we refer to it as nonlinear Fenchel conjugation. We investigate elementary properties including the Fenchel-Moreau biconjugation theorem. Whenever the domain exhibits additional structure, the restriction to a suitable subset of test functions allows further results to be derived. For example, on smooth manifolds, the restriction to smooth test functions allows us to state the Fenchel-Young theorem for the viscosity Fréchet subdifferential. On Lie groups, the restriction to real-valued group homomorphisms relates nonlinear Fenchel conjugation to infimal convolution and yields a notion of convexity.
format Preprint
id arxiv_https___arxiv_org_abs_2409_04492
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Nonlinear Fenchel Conjugates
Schiela, Anton
Herzog, Roland
Bergmann, Ronny
Functional Analysis
Differential Geometry
Optimization and Control
The classical concept of Fenchel conjugation is tailored to extended real-valued functions defined on linear spaces. In this paper we generalize this concept to functions defined on arbitrary sets that do not necessarily bear any structure at all. This generalization is obtained by replacing linear test functions by general nonlinear ones. Thus, we refer to it as nonlinear Fenchel conjugation. We investigate elementary properties including the Fenchel-Moreau biconjugation theorem. Whenever the domain exhibits additional structure, the restriction to a suitable subset of test functions allows further results to be derived. For example, on smooth manifolds, the restriction to smooth test functions allows us to state the Fenchel-Young theorem for the viscosity Fréchet subdifferential. On Lie groups, the restriction to real-valued group homomorphisms relates nonlinear Fenchel conjugation to infimal convolution and yields a notion of convexity.
title Nonlinear Fenchel Conjugates
topic Functional Analysis
Differential Geometry
Optimization and Control
url https://arxiv.org/abs/2409.04492