sln(r)

2.14.18. The structure of open sets in R. Any nonempty open subset of R can be written as a finit...

In mathematics, open sets are a generalization of open intervals in the real line. In a metric sp...

Let U be an open set in R. Then U is a countable union of disjoint intervals. This question has p...

Open sets are among the most important subsets of R. A collection of open sets is called a topolo...