Infinite loop space machine

In topology, a branch of mathematics, given a topological monoid X up to homotopy, 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,. Then the machine produces the group completion. The space may be described by the K-theory spectrum of S.
In 1977 Robert Thomason proved the
equivalence of all infinite loop space machines. He published this result next year in a joint paper with John Peter May.