We introduce and study
proper homotopy invariants of the Lusternik-Schnirelmann type, p-cat(−), p-Cat(−),
and cat 𝜀(−) in the category of T2-locally compact spaces and proper maps. As an
application, ℝn(n≠3) is characterized as (i) the unique open manifold X with
p-Cat(X) = 2, or (ii) the unique open manifold with one strong end and
p-cat(x) = 2.