Boundary Map
The map H_n(X,A)->H_(n-1)(A) appearing in the long exact sequence of a pair axiom.
See also
Long Exact Sequence of a Pair AxiomExplore with Wolfram|Alpha
WolframAlpha
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Cite this as:
Weisstein, Eric W. "Boundary Map." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/BoundaryMap.html