Assertion: set's number | /r/HasAspect | rational number
Facets:
value: as a countable dense subset
type: OTHER
Source sentences:
text: — for instance, the rational numbers are a dense subset of the real numbers because every real number either is a rational number or has a rational number arbitrarily close to it (see Diophantine approximation).
text: The real numbers with the usual topology have the rational numbers as a countable dense subset which shows that the cardinality of a dense subset of a topological space may be strictly smaller than the cardinality of the space itself.