Order intervals of selfadjoint linear operators and nonlinear homeomorphisms
Order intervals of selfadjoint linear operators and nonlinear homeomorphisms
In this paper, we prove an invertibility criterion for order intervals of self-adjoint linear operators.We then use this to improve and clarify a good deal of recent work (see Bates [2], Bates and Castro [3] and Mawhin [12] for example) on homeomorphism theorems of Ahmad-Lazer type.In particular, we prove a …