Metric characterizations of dimension for separable metric spaces

Separable Fuzzy Metric Spaces

Many authors have introduced the concept of fuzzy metric spaces in different ways.In this paper, we get a special structure for some separable fuzzy metric and M-fuzzy metric spaces, where the metric space has been introduced by George and Veermani.

Characterizations of Compactness for Metric Spaces

Characterizations of Compactness for Metric Spaces

Definition. Let X be a metric space with metric d. (a) A collection {G α } α∈A of open sets is called an open cover of X if every x ∈ X belongs to at least one of the G α , α ∈ A. An open cover is finite if the index set A is finite. (b) X is compact if every open cover of X contains a finite subcover. Definition. Let X be a metric space with metric d and let A ⊂ X. We say that A is a compact s...

Characterizations of Sobolev Inequalities on Metric Spaces

We present isocapacitary characterizations of Sobolev inequalities in very general metric measure spaces.

Isometry Groups of Separable Metric Spaces

We show that every locally compact Polish group is isomorphic to the isometry group of a proper separable metric space. This answers a question of Gao and Kechris. We also analyze the natural action of the isometry group of a separable ultrametric space on the space. This leads us to a structure theorem representing an arbitrary separable ultrametric space as a bundle with an ultrametric base a...