On sufficient conditions for mixed monotonicity

TL;DR

This paper clarifies the definitions of mixed monotone systems, introduces two broad sufficient conditions for mixed monotonicity in Euclidean spaces, and discusses their computational advantages, highlighting the property's generic nature.

Contribution

It provides a unified clarification of mixed monotone system definitions and introduces more general sufficient conditions, enhancing verification methods.

Findings

Sufficient conditions are more general than existing ones.

Mixed monotonicity is shown to be a very generic property.

Discussion on computational usefulness of the conditions.

Abstract

Mixed monotone systems form an important class of nonlinear systems that have recently received attention in the abstraction-based control design area. Slightly different definitions exist in the literature, and it remains a challenge to verify mixed monotonicity of a system in general. In this paper, we first clarify the relation between different existing definitions of mixed monotone systems, and then give two sufficient conditions for mixed monotone functions defined on Euclidean space. These sufficient conditions are more general than the ones from the existing control literature, and they suggest that mixed monotonicity is a very generic property. Some discussions are provided on the computational usefulness of the proposed sufficient conditions.