In topology, a branch of mathematics, given a topological monoid X up to homotopy (in a nice way), an infinite loop space machine produces a group completion of X together with infinite loop space structure. For example, one can take X to be the classifying space of a symmetric monoidal category S; that is,
X=BS
BS\toK(S)
K(S)
In 1977 Robert Thomason proved theequivalence of all infinite loop space machines[1] (he was just 25 years old at the moment.) He published this result next year in a joint paper with John Peter May.