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Main Author: Lovász, László
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2504.18873
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author Lovász, László
author_facet Lovász, László
contents In a seminal paper, Choquet introduced an integral formula to extend a monotone increasing setfunction on a sigma-algebra to a (nonlinear) functional on bounded measurable functions. The most important special case is when the setfunction is submodular; then this functional is convex (and vice versa). In the finite case, an analogous extension was introduced by this author; this is a rather special case, but no monotonicity was assumed. In this note we show that Choquet's integral formula can be applied to all submodular setfunctions, and the resulting functional is still convex. We extend the construction to submodular setfunctions defined on a set-algebra (rather than a sigma-algebra). The main property of submodular setfunctions used in the proof is that they have bounded variation. As a generalization of the convexity of the extension, we show that (under smoothness conditions) a ``lopsided'' version of Fubini's Theorem holds.
format Preprint
id arxiv_https___arxiv_org_abs_2504_18873
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Choquet extension of non-monotone submodular setfunctions
Lovász, László
Combinatorics
05C63, 05B35, 28E99, 52B40
In a seminal paper, Choquet introduced an integral formula to extend a monotone increasing setfunction on a sigma-algebra to a (nonlinear) functional on bounded measurable functions. The most important special case is when the setfunction is submodular; then this functional is convex (and vice versa). In the finite case, an analogous extension was introduced by this author; this is a rather special case, but no monotonicity was assumed. In this note we show that Choquet's integral formula can be applied to all submodular setfunctions, and the resulting functional is still convex. We extend the construction to submodular setfunctions defined on a set-algebra (rather than a sigma-algebra). The main property of submodular setfunctions used in the proof is that they have bounded variation. As a generalization of the convexity of the extension, we show that (under smoothness conditions) a ``lopsided'' version of Fubini's Theorem holds.
title Choquet extension of non-monotone submodular setfunctions
topic Combinatorics
05C63, 05B35, 28E99, 52B40
url https://arxiv.org/abs/2504.18873