Books by Seppo Heikkila

This unified, comprehensive treatment of an order-theoretic fixed point theory in partially ordered sets shows its various useful interactions with topological structures. Covering the preliminaries before moving to more advanced topics makes it approachable.

Features a theoretical framework to model phenomena with discontinuous changes. This book presents a generalized monotone iterative method in terms of upper and lower solutions appropriate for the study of discontinuous nonlinear differential equations. It also applies this method to derive suitable fixed point theorems in ordered abstract spaces.