Monotone semiflows with respect to high-rank cones on a Banach space

TL;DR

This paper studies the structure of semiflows in Banach spaces with high-rank cone monotonicity, revealing their limit set behaviors and extending classical results to nonsmooth, infinite-dimensional systems.

Contribution

It introduces a framework for analyzing semiflows with high-rank cone monotonicity, including a Poincaré-Bendixson theorem for rank 2, applicable to nonsmooth and infinite-dimensional systems.

Findings

Limit sets are either ordered, contain only equilibria, or have a homoclinic property.

Ordered limit sets are topologically conjugate to flows on finite-dimensional spaces.

Established a Poincaré-Bendixson type theorem for rank 2 systems.

Abstract

We consider semiflows in general Banach spaces motivated by monotone cyclic feedback systems or differential equations with integer-valued Lyapunov functionals. These semiflows enjoy strong monotonicity properties with respect to cones of high ranks, which imply order-related structures on the $\omega$-limit sets of precompact semi-orbits. We show that for a pseudo-ordered precompact semi-orbit the $\omega$-limit set $\Omega$ is either ordered, or is contained in the set of equilibria, or possesses a certain ordered homoclinic property. In particular, we show that if $\Omega$ contains no equilibrium, then $\Omega$ itself is ordered and hence the dynamics of the semiflow on $\Omega$ is topologically conjugate to a compact flow on $\mathbb{R}^k$ with $k$ being the rank. We also establish a Poincar\'{e}-Bendixson type Theorem in the case where $k=2$. All our results are established without the smoothness condition on the semiflow, allowing applications to such cellular or physiological feedback systems with piecewise linear vector fields and to such infinite dimensional systems where the $C^1$-Closing Lemma or smooth manifold theory has not been developed.