chapter  17
8 Pages

Mayer-Vietoris Sequence

WithMarvin J. Greenberg, John R. Harper

We now consider triads (X, X 1, X 2), ordered triples of spaces such that X 1 and X 2 are subspaces of X. We have inclusion maps k 1 : ( X 2 , X 1 ∩ X 2 ) → ( X 1 ∪ X 2 , X 1 ) , k 2 : ( X 1 , X 1 ∩ X 2 ) → ( X 1 ∪ X 2 , X 2 )