The Euler-Poincaré-Hopf theorem for flat connections in some transitive Lie algebroids

Kubarski, Jan

Czechoslovak Mathematical Journal, Tome 56 (2006) no. 2, pp. 359-376.

Résumé

This paper is a continuation of [19], [21], [22]. We study flat connections with isolated singularities in some transitive Lie algebroids for which either $\mathbb{R}$ or $\mathrm{s}l(2,\mathbb{R})$ or $\mathrm{so}(3)$ are isotropy Lie algebras. Under the assumption that the dimension of the isotropy Lie algebra is equal to $n+1$, where $n$ is the dimension of the base manifold, we assign to any such isolated singularity a real number called an index. For $\mathbb{R}$-Lie algebroids, this index cannot be an integer. We prove the index theorem (the Euler-Poincaré-Hopf theorem for flat connections) saying that the index sum is independent of the choice of a connection. Multiplying this index sum by the orientation class of $M$, we get the Euler class of this Lie algebroid. Some integral formulae for indices are given.

Détail

Classification : 53D17, 55R25, 57R19, 57R20, 58H05
Mots-clés : Lie algebroid; Euler class; index theorem; integration over the fibre; flat connection with singularitity