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A stratification of the inertia space of a $G$-manifold for compact Lie group $G$

Christopher Seaton
(Rhodes College)
Onsdag, 12 september, 2012, at 16:00-17:00, in Aud. D3 (1531-215)
Let $G$ be a compact Lie group and let $M$ be a smooth $G$-manifold. If $G$ happens to act locally freely on $M$, then the quotient of $M$ by the $G$-action is an example of an orbifold. In the study of the geometry of orbifolds, an object called the inertia orbifold has played a major role. The inertia orbifold is a disjoint union of orbifolds given by the quotient of the space of loops of the translation groupoid, a smooth manifold, by a natural action of the translation groupoid itself.

If the action of $G$ is not assumed to be locally free, then the space of loops of the translation groupoid is no longer a smooth manifold and the quotient is no longer an orbifold. In this case, we refer to the quotient of the space of loops as the inertia space of the $G$-manifold $M$. We will describe an explicit Whitney stratification of the inertia space. Using this stratification, we will present a de Rham theorem for cohomology of differential forms on the inertia space with respect to this stratification. (Joint work with Carla Farsi and Markus Pflaum)
Organiseret af: QGM
Kontaktperson: Jørgen Ellegaard Andersen