Uniform property


In the mathematical field of topology a uniform property or uniform invariant is a property of a uniform space that is invariant under uniform isomorphisms.
Since uniform spaces come as topological spaces and uniform isomorphisms are homeomorphisms, every topological property of a uniform space is also a uniform property. This article is concerned with uniform properties that are not topological properties.

Uniform properties

Separated. A uniform space X is separated if the intersection of all entourages is equal to the diagonal in X × X. This is actually just a topological property, and equivalent to the condition that the underlying topological space is Hausdorff.Complete. A uniform space X is complete if every Cauchy net in X converges.Totally bounded. A uniform space X is totally bounded if for each entourage E ⊂ X × X there is a finite cover of X such that Ui × Ui is contained in E for all i. Equivalently, X is totally bounded if for each entourage E there exists a finite subset of X such that X is the union of all E. In terms of uniform covers, X is totally bounded if every uniform cover has a finite subcover.Compact. A uniform space is compact if it is complete and totally bounded. Despite the definition given here, compactness is a topological property and so admits a purely topological description.Uniformly connected. A uniform space X is uniformly connected if every uniformly continuous function from X to a discrete uniform space is constant.Uniformly disconnected. A uniform space X is uniformly disconnected if it is not uniformly connected.