Special auxiliary tools

Abstract

In evolution problems, one scalar variable, denoted by t and having a meaning of time, takes a special role, which is also reflected by mathematical analysis. In particular, here we first present a few useful assertions about spaces of abstract functions on a “time” interval I := [0, T ], introduced already in Section 1.5, but now possessing additionally derivatives with respect to time. Always, T will denote a fixed finite time horizon.