Work

Two Abstract Methods of Lower and Upper Solutions with Applications

Year: 2026

Type: article

Abstract: In this paper, we present two abstract methods for constructing a lower and an upper solution for a fixed point equation. The first method applies when the nonlinear operator is a composition of a linear and a nonlinear mapping, while the second method applies when the nonlinear operator satisfies an inequality of Harnack type. An application is provided for each method.

Source: Results in Mathematics

DOI: 10.1007/s00025-026-02631-6

Author: Andrei Stan

Institutions: Babeș-Bolyai University, Tiberiu Popoviciu Institute of Numerical Analysis

Language: English

Topic: Fixed Point Theorems Analysis

Subfield: Geometry and Topology

Field: Mathematics

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $3,090

OpenAlex ID: W7137919902