One of the Eilenberg-Steenrod axioms. It states that, for every pair , there is a natural long exact sequence
where the map is induced by the inclusion map and is induced by the inclusion map . The map is called the boundary map.
One of the Eilenberg-Steenrod axioms. It states that, for every pair , there is a natural long exact sequence
where the map is induced by the inclusion map and is induced by the inclusion map . The map is called the boundary map.
Weisstein, Eric W. "Long Exact Sequence of a Pair Axiom." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/LongExactSequenceofaPairAxiom.html