Published Paper

Inserted: 12 jul 2025
Last Updated: 16 oct 2026

Journal: Communications in Contemporary Mathematics
Year: 2026
Doi: 10.1142/S0219199726500719

Abstract:

In this paper, we study the connection between cyclic quasi-monotonicity and quasi-convexity, focusing on whether every cyclically quasi-monotone (possibly multi-valued) map is included in the normal cone operator of a quasi-convex function, in analogy with Rockafellar's theorem for convex functions. We provide a positive answer for locally Lipschitz, non-vanishing maps in any dimension, as well as for general multi-maps in dimension $1$. We further discuss connections to revealed preference theory in economics and to $L^\infty$ optimal transport. Finally, we present explicit constructions and examples, highlighting the main challenges that arise in the general case.

Keywords: Optimal transport, convex analysis, quasi-monotonicity, quasi-convexity, $L^\infty$ optimal transport, revealed preference, Rockafellar theorem

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