Pollanem, Marco

With wide applications in many fields such as engineering, physics, chemistry, biology and social sciences, semi-linear equations have attracted great interests of researchers from various areas. In the study of existence of solutions for such class of equations, a general and commonly applied method is the compression cone method for fixed-point index. The main idea is to construct a cone in an ordered Banach space based on the linear part so that the nonlinear part can be examined in a relatively smaller region.

In this thesis, a new class of cone is proposed as a generalization to previous work. The construction of the cone is based on properties of both the linear and nonlinear part of the equation. As a result, the method is shown to be more adaptable in applications. We prove new results for both semi-linear integral equations and algebraic systems.

Applications are illustrated by examples. Limitations of such new method are also discussed.

Keywords: Algebraic systems; compression cone method; differential equations; existence of solutions; fixed point index; integral equations; semi-linear equations.

Author Keywords: algebraic systems, differential equations, existence of solutions, fixed point index, integral equations, semi-linear equations