On the operators with partial integrals in the function spaces of two variables

A. S. Kalitvin ; V. A. Kalitvin

Taurida Journal of Computer Science Theory and Mathematics, no. 3 (2017), pp. 17-27

Résumé

Linear operators with partial integrals are studied. Using Banach's closed graph theorem, a general theorem on the continuity acting from a space $X$ to a space $Y$ of linear operator $K$ with partial integrals is proved. Here $X$ and $Y$ are complete metric spaces of measurable functions with a shift-invariant metric, and the space $X$ contains, together with each function, its modulus. With the application of this theorem, the continuity acting of the operator $K$ in various function spaces is established. The conditions of this theorem are not satisfied by spaces of continuously differentiable functions. In this connection, a theorem on continuity acting of the operator $K$ in spaces of continuously differentiable functions is established. The conditions for continuity acting of the operator $K$ from the spaces of continuously differentiable functions to various classes of function spaces are obtained. The continuity of the operator $K$ defined on the space $BV$ of bounded variation functions of two variables is proved, and the acting conditions for this operator in the space $BV$ of functions defined on a finite rectangle are established.

Détail

Keywords: linear operators with partial integrals, Banach's closed graph theorem, acting and continuity of the operators, function spaces, the space BV of bounded variation functions, conditions for the action in BV.