A T3 Cauchy space which has a
regular completion is shown to have a T3 completion, but an example shows that
such Cauchy spaces need not have strict T3 completions. Various conditions are
found for the existence of T3 completions and strict T3 completions; for
instance, every Cauchy-separated, locally compact, T3 Cauchy space has a T3
completion. Convergence spaces and topological spaces which have a coarsest
compatible Cauchy structure with a strict T3 completion are characterized, as
are those spaces for which every compatible T3 Cauchy structure has a T3
completion.