Groupoids and discrete variational mechanics

Alan Weinstein, University of California, Berkeley, Mathematics

Some constructions in a paper by Jalnapurkar, Leok, Marsden, and West on discrete Routh reduction appear to be related to objects in a complex of differential forms associated to a differential groupoid. In anticipation of making this relation more precise, I will present in this talk an exposition of the theory of these differential forms, including an introduction to groupoids. The talk will contain several examples of groupoids occurring in mechanics.