Conditional Analysis on R^d

Abstract

This paper provides versions of classical results from linear algebra, real analysis and convex analysis in a free module of finite rank over the ring L0 of measurable functions on a σ-finite measure space. We study the question whether a submodule is finitely generated and introduce the more general concepts of L0-affine sets, L0-convex sets, L0-convex cones, L0-hyperplanes and L0-halfspaces. We investigate orthogonal complements, orthogonal decompositions and the existence of orthonormal bases. We also study L0-linear, L0-affine, L0-convex and L0-sublinear functions and introduce notions of continuity, differentiability, directional derivatives and subgradients. We use a conditional version of the Bolzano–Weierstrass theorem to show that conditional Cauchy sequences converge and give conditions under which conditional optimization problems have optimal solutions. We prove results on the separation of L0-convex sets by L0-hyperplanes and study L0-convex conjugate functions. We provide a result on the existence of L0-subgradients of L0-convex functions, prove a conditional version of the Fenchel–Moreau theorem and study conditional inf-convolutions.