Since 'X' is separable, let be a countable dense subset.

Let be a countable collection of open dense subsets.

It should be noticed that this terminology is different from the notion of a dense subset in general topology.

It also has a countable dense subset, namely the set of rational numbers.

In a topological space, every constructible set contains a dense open subset of its closure.

In g they form an open and dense subset.

To make this more formal, one has to explain that T is bounded only on a dense subset and can be completed.

A space is separable if it has a countable dense subset.

In mathematical analysis, the rational numbers form a dense subset of the real numbers.

In this way, arbitrarily dense subsets of the group can be found.