De Rham invariant
In geometric topology, the de Rham invariant is a mod 2 invariant of a -dimensional manifold, that is, an element of – either 0 or 1. It can be thought of as the simply-connected symmetric L-group and thus analogous to the other invariants from L-theory: the signature, a 4k-dimensional invariant, and the Kervaire invariant, a -dimensional quadratic invariant
It is named for Swiss mathematician Georges de Rham, and used in surgery theory.Definition
The de Rham invariant of a -dimensional manifold can be defined in various equivalent ways:
