e/Double (manifold)

Information
has gloss	eng: In the subject of manifold theory in mathematics, if M is a manifold with boundary, its double is obtained by gluing two copies of M together along their common boundary. Precisely, the double is M \times \0,1\} / \sim where (x,0) \sim (x,1) for all x \in \partial M.
lexicalization	eng: double
instance of	(noun) a set of points such as those of a closed surface or an analogue in three or more dimensions manifold