The compact objectsin ∞Grpd are the retracts of finite homotopy types (finite CW-complexes). Not every such retract is itself a finite homotopy type; the vanishing of Wall’s finiteness obstruction is a necessary and sufficient condition for this to happen.
C. T. C. Wall, Finiteness conditions for CW-complexes I pdf
C. T. C. Wall, Finiteness conditions for CW-complexes II pdf
Last revised on March 16, 2015 at 19:58:15. See the history of this page for a list of all contributions to it.