Lefschetz duality

In mathematics, Lefschetz duality is a version of Poincaré duality in geometric topology, applying to a manifold with boundary. Such a formulation was introduced by Solomon Lefschetz in the 1920s, at the same time introducing relative homology, for application to the Lefschetz fixed-point theorem [Biographical Memoirs By National Research Council Staff (1992), p. 297.] . There are now numerous formulations of Lefschetz duality or Poincaré-Lefschetz duality, or Alexander-Lefschetz duality.

Formulations

Let "M" be an orientable closed manifold of dimension "n", with boundary "N", and let "z" be the fundamental class of "M". Then cap product with "z" induces a pairing of the (co)homology groups of "M" and the relative (co)homology of the pair ("M", "N"); and this gives rise to isomorphisms of "H"^"k"("M", "N") with "H"_{"n - k"}("M"), and of "H"_"k"("M", "N") with "H"^{"n - k"}("M") [James W. Vick, "Homology Theory: An Introduction to Algebraic Topology" (1994), p. 171.] .

Here "N" can in fact be empty, so Poincaré duality appears as a special case of Lefschetz duality.

There is a version for triples. Let "A" and "B" denote two subspaces of the boundary "N", themselves compact orientable manifolds with common boundary "Z", which is the intersection of "A" and "B". Then there is an isomorphism :$D\_M:\; H^p(M,A,Z)\; o\; H\_\{n-p\}(M,B,Z).$

Notes

External links

*http://eom.springer.de/P/p073020.htm