Assertion: ring's set | /r/HasProperty | closed under union
Facets:
Source sentences:
text: The open sets and closed sets of any topological space are closed under both unions and intersections.
text: The open sets and closed sets of any topological space are closed under both unions and intersections.
text: If T is any transformation defined on a space, then the sets that are mapped into themselves by T are closed under both unions and intersections.