Approximations by differences of lower semicontinuous functions

Abstract

A classical theorem of W.Sierpi\'nski, S. Mazurkiewicz and S.Kempisty
says that the class of all differences of lower semicontinuous functions is
uniformly dense in the space of all Baire--one functions.  We show a
generalization of this result to a more general situations and derive an
abstract theorem in the case of a binormal topological space.