Properness and topological degree for general elliptic operators
The authors study elliptic operators in Hölder spaces: the Fredholm property for linear operators, properness and topological degree for nonlinear operators. The construction of the degree uses both the Fredholm property and the properness. Moreover, they also discuss the main ideas underlying normal solvability, properness and topological degree for general elliptic operators in the Douglis-Nirenberg sense.
scientific article; zbMATH DE number 1883743