On the density of the space of continuous and uniformly continuous functions

摘要

For X a metrizable space and (Y, ρ) a metric space, with Y pathwise connected, we compute the density of (C(X, (Y, ρ)), σ)—the space of all continuous functions from X to (Y, ρ), endowed with the supremum metric σ. Also, for (X, d) a metric space and (Y, ‖ · ‖) a normed space, we compute the density of (UC((X, d), (Y, ρ)), σ) (the space of all uniformly continuous functions from (X, d) to (Y, ρ), where ρ is the metric induced on Y by ‖ · ‖). We also prove that the latter result extends only partially to the case where (Y, ρ) is an arbitrary pathwise connected metric space. To carry such an investigation out, the notions of generalized compact and generalized totally bounded metric space, introduced by the author and A. Barbati in a former paper, turn out to play a crucial role. Moreover, we show that the first-mentioned concept provides a precise characterization of those metrizable spaces which attain their extent.