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Strøm's theorem

Strøm’s theorem

Let (X,A)(X,A) and (Y,B)(Y,B) be NDR-pairs. Their product in the category of topological pairs

(X×Y,X×BA×Y) (X\times Y,X\times B\cup A\times Y)

is also an NDR-pair.

Last revised on December 3, 2009 at 23:12:57. See the history of this page for a list of all contributions to it.