
In the modern theory of boundary value problems the following ap- proach to investigation is agreed upon (we call it the functional approach): some functional spaces are chosen; the statements of boundary value prob- the basis of these spaces; and the solvability of lems are...

In the modern theory of boundary value problems the following ap- proach to investigation is agreed upon (we call it the functional approach): some functional spaces are chosen; the statements of boundary value prob- the basis of these spaces; and the solvability of lems are...