One service mathematics has rendered the "Et moi, "'f si favait su comment en revenir. je n 'y serais point alleC human raoe. It hat put common sense back where it belongs. on the topmost shelf next Jules Verne to the dusty canister labelled 'discarded non· The series is divergent; therefore we may be smse'. Eric T. Bell able to do something with it. O. H eaviside Mathematics is a tool for thought. A highly necessary tool in a world where both feedback and non linearities abound. Similarly, all kinds of parts of mathematics serve as tools for other parts and for other sciences. Applying a simple rewriting rule to the quote on the right above one finds such statements as: 'One service topology has rendered mathematical physics .. .'; 'One service logic has rendered com puter science .. .'; 'One service category theory has rendered mathematics .. .'. All arguably true. And all statements obtainable this way form part of the raison d'elre of this series.

Inhalt

1. Some information from the theory of linear operators.- 2. Boundary values of solutions of homogeneous operator differential equations.- 3. Extensions of symmetric operators.- 4. Boundary value problems for a second-order elliptic-type operator differential equation.- 5. Boundary values of solutions of differential equations in a Banach space.- Bibliographical Comments.- References.