2002, D. A. Vladimirov, Boolean Algebras in Analysis, page 133:
Theorem 3. 1) Every two disjoint closed sets in a totally disconnected compact space are separated by disjoint clopen sets. 2) Every algebra of clopen sets which separates the points of a totally disconnected compact space contains all clopen sets.
参考
Interval (mathematics) § Definitions and terminology on WikipediaWikipedia ; the half-open interval defined there is not to be confused with the clopen set.
名詞
clopen (pluralclopens)
A pair of work shifts in which a worker works a closing shift one day and then works an opening shift the following day.
James is on vacation, so I've got to do a clopen this weekend to cover his shifts.