Compactifications, Hartman functions and (weak) almost periodicity
We investigate Hartman functions on a topological group G. Recall that (ι,C) is a group compactification of G if C is a compact group, ι: G → C is a continuous group homomorphism and ι(G) ⊆ C is dense. A bounded function f: G → ℂ is a Hartman function if there exists a group compactification (ι,C) and F: C → ℂ such that f = F∘ι and F is Riemann integrable, i.e. the set of discontinuities of F is a null set with respect to the Haar measure. In particular, we determine how large a compactification...