Induced mappings of homology decompositions

Abstract

We give conditions for a map of spaces to induce maps of the homology decompositions of the spaces which are compatible with the homology sections and dual Postnikov invariants. Several applications of this result are obtained. We show how the homotopy type of the (n + 1)st homology section depends on the homotopy type of the nth homology section and the (n+ 1)st homology group. We prove that all homology sections of a co-H-space are coH-spaces, all n-equivalences of the homology decomposition are co-H-maps and, under certain restrictions, all dual Postnikov invariants are co-H-maps. We give a new proof of a result of Berstein and Hilton which gives conditions for a co-H-space to be a suspension.