Sections of convex bodies and splitting problem for selections

Let F1 :X → Y1 and F2 :X → Y2 be any convex-valued lower semicontinuous mappings and let L:Y1 ⊕Y2→Y be any linear surjection. The splitting problem is the problem of representation of any continuous selection f of the composite mapping L(F1;F2) in the form f = L(f1;f2), where f1 and f2 are some continuous selections of F1 and F2, respectively. We prove that the splitting problem always admits an approximate solution with fi being an ε-selection (Theorem 2.1). We also propose a special case of finding exact splittings, whose occurrence is stable with respect to continuous variations of the data (Theorem 3.1) and we show that, in general, exact splittings do not exist even for the finite-dimensional range. © 2007 Elsevier Inc. All rights reserved