The first two chapters of this book are devoted to convexity in the
classical sense, for functions of one and several real variables
respectively. This gives a background for the study in the following
chapters of related notions which occur in the theory of linear partial
differential equations and complex analysis such as (pluri-)subharmonic
functions, pseudoconvex sets, and sets which are convex for supports or
singular supports with respect to a differential operator. In addition,
the convexity conditions which are relevant for local or global
existence of holomorphic differential equations are discussed, leading
up to Trépreau's theorem on sufficiency of condition (capital Greek
letter Psi) for microlocal solvability in the analytic category.