Speaker: Henry Jacobs (Imperial College London)

Abstract: Associated to each fiber bundle  : Q ! B there exists a groupoid G consisting of morphisms between the fibers. Moreover, there is a natural Lie groupoid morphism between the pair groupoid Q  Q and G. This Lie groupoid morphism provides a recipe for identifying various Lagrangian systems as ones which naturally evolve on Lie groupoids. Moreover, this morphism provides an alternative perspective on reduction by symmetry (albeit a mathematically equivalent one). This talk seeks to explain these ideas through a sequence of examples starting with the rigid body and ending with the dynamics of soap bubbles.