Single loop space decompositions

The method of single loop space decompositions, in which CIX is factored into minimal factors, is an important one for understanding the unstable homotopy of many simply-connected spaces X. This paper begins with a survey of the major known theorems along these lines. We then give a necessary and sufficient condition for QX to be decomposable as a product of spaces belonging to a certain list. We conclude with a nontrivial instance of an application of this condition. 1. Background and summary of the major known decomposition theorems In this introduction we provide a summary of the major known theorems of a general nature regarding single loop space decompositions. The original loop space decomposition was discovered by Hilton (H) in 1955 by building upon work of George Whitehead; it was later generalized by Milnor. Theorem 1 (Hilton). Let W be a simply-connected finite type wedge of spheres, i.e., W = V/S1"'. ni>2, and «, —> oo if the index set is infinite. Then