Poincaré Duality
The Betti numbers of a compact orientable n-manifold satisfy the relation
| b_i=b_(n-i). |
See also
Betti Number, Homology IntersectionCite this as:
Weisstein, Eric W. "Poincaré Duality." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/PoincareDuality.html