one-point compactification

{\displaystyle \mathbb {Q} } 的單點緊化（英语：one-point compactification）是緊空間，從而在意義1及2下是局部緊，但在意義3下則不然。 任何無窮集上的特定點拓撲（英语：particular point topology）在意義1及3下是局部緊，但在意義2下則不

need to be compactified on a Calabi–Yau manifold. (In string theory, compactification is a generalization of Kaluza–Klein theory, which was first proposed