Involutory Hopf group-coalgebras and flat bundles over 3-manifolds
Volume 188 / 2005
Fundamenta Mathematicae 188 (2005), 241-270
MSC: 57M27, 16W30.
DOI: 10.4064/fm188-0-11
Abstract
Given a group $\pi$, we use involutory Hopf $\pi$-coalgebras to define a scalar invariant of flat $\pi$-bundles over 3-manifolds. When $\pi=1$, this invariant equals the one for 3-manifolds constructed by Kuperberg from involutory Hopf algebras. We give examples which show that this invariant is non-trivial.
