Inhalt

and summary.- Multiplication theorems and square theorems; Bourlet operators.- Substitution operators. The Schröder equation.- Continuous iteration. Commuting substitution operators.- Relations beiween Bourlet operators of the specific form.- Superposition of substitution operators.- Integral operators: Remarks and definitions.- The theorems of Weyl and von Neumann on hermitean Carleman operators.- Recent results on Carleman operators.- Strong Carleman operators.- Convergence theorems.- Transformation of strong Kernels.- Operators of locally bounded range.- Concluding remakrs. Open questions.