Small sets in convex geometry and formal independence over ZFC

Small Sets in Convex Geometry and Formal Independence over Zfc

To each closed subset S of a finite dimensional Euclidean space corresponds a σ-ideal of sets J (S) which is σ-generated over S by the convex subsets of S. The set-theoretic properties of this ideal hold geometric information about the set. We discuss the relation of reducibility between convexity ideals and the connections between convexity ideals to other types of ideals, such as the ideals w...

Independence Concepts for Convex Sets of Probabilities

In this paper we study different concepts of independence for convex sets of probabilities. There will be two basic ideas for independ­ ence. The first is irrelevance. Two variables are independent when a change on the know­ ledge about one variable does not affect the other. The second one is factorization. Two variables are independent when the joint con­ vex set of probabilities can be decom...

Functionally closed sets and functionally convex sets in real Banach spaces

‎Let $X$ be a real normed  space, then  $C(subseteq X)$  is  functionally  convex  (briefly, $F$-convex), if  $T(C)subseteq Bbb R $ is  convex for all bounded linear transformations $Tin B(X,R)$; and $K(subseteq X)$  is  functionally   closed (briefly, $F$-closed), if  $T(K)subseteq Bbb R $ is  closed  for all bounded linear transformations $Tin B(X,R)$. We improve the    Krein-Milman theorem  ...

Small Convex Quadrangulations of Point Sets

Differentiability of convex functions outside small sets

Small sets. We are going to present some results of the following type: under a suitable assumption on a normed space X, each continuous convex function, defined on an open convex set A ⊂ X, is (Gâteaux or Fréchet) differentiable outside a set which is in some sense small. It is natural to ask that a nonempty family S ⊂ 2X whose elements are considered “small sets” satisfy the following conditi...