Comparison of spectral radii and Collatz-Wielandt numbers for homogeneous maps, and other applications of the monotone companion norm on ordered normed vector spaces

TL;DR

This paper investigates the properties of the monotone companion norm in ordered normed vector spaces, compares spectral radii and Collatz-Wielandt numbers, and applies these concepts to integral equations and nonlinear positive maps.

Contribution

It introduces and analyzes the monotone companion norm and half-norm, providing new comparison principles and conditions for spectral properties in ordered spaces.

Findings

Comparison principles for solutions of integral equations

Conditions for point-dissipativity of nonlinear maps

Bounds and comparisons of spectral radii and Collatz-Wielandt numbers

Abstract

It is well known that an ordered normed vector space $X$ with normal cone $X_+$ has an order-preserving norm that is equivalent to the original norm. Such an equivalent order-preserving norm is given by \begin{equation} \sharp x \sharp = \max \{ d(x, X_+), d(x, - X_+)\}, \qquad x \in X. \end{equation} This paper explores the properties of this norm and of the half-norm $\psi(x) = d(x,-X_+)$ independently of whether or not the cone is normal. We use $\psi$ to derive comparison principles for the solutions of abstract integral equations, derive conditions for point-dissipativity of nonlinear positive maps, compare Collatz-Wielandt numbers, bounds, and order spectral radii for bounded homogeneous maps and give conditions for a local upper Collatz-Wielandt radius to have a lower positive eigenvector.