Excisive triad

In topology, a branch of mathematics, an excisive triad is a triple $(X; A, B)$ of topological spaces such that A, B are subspaces of X and X is the union of the interior of A and the interior of B.^[1] Note B is not required to be a subspace of A.

See also

• Homotopy excision theorem

Notes

1. May, Ch 10. Section 7.

References

• J. P. May, A concise course in algebraic topology
• Munkres, James; Topology, Prentice Hall; 2nd edition (December 28, 1999). ISBN 0-13-181629-2.