Department of

# Mathematics

Seminar Calendar
for events the day of Monday, October 7, 2013.

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events for the
events containing

Questions regarding events or the calendar should be directed to Tori Corkery.
    September 2013          October 2013          November 2013
Su Mo Tu We Th Fr Sa   Su Mo Tu We Th Fr Sa   Su Mo Tu We Th Fr Sa
1  2  3  4  5  6  7          1  2  3  4  5                   1  2
8  9 10 11 12 13 14    6  7  8  9 10 11 12    3  4  5  6  7  8  9
15 16 17 18 19 20 21   13 14 15 16 17 18 19   10 11 12 13 14 15 16
22 23 24 25 26 27 28   20 21 22 23 24 25 26   17 18 19 20 21 22 23
29 30                  27 28 29 30 31         24 25 26 27 28 29 30



Monday, October 7, 2013

10:00 am in 145 Altgeld Hall,Monday, October 7, 2013

#### Lie Algebroid Spray

###### Songhao Li (Washington University Math)

Abstract: Analogous to the spray in Riemannian geometry, we introduce the Lie algebroid spray, or A-spray. A special case is the Poisson spray as introduced by Crainic and Marcut. As an application, we show that the source-simply-connected symplectic groupoid of a log symplectic surface is diffeomorphic to the cotangent bundle in such a way that the source map coincide with the bundle projection. (Joint work in progress with Marco Gualtieri)

1:30 pm in 345 Altgeld Hall,Monday, October 7, 2013

#### Optimal Cyclic Processes and Subriemannian Geodesics

###### Roger Brockett   [email] (Harvard EECS)

Abstract: The basic mechanisms involved in wide variety of engineering and biological processes depend on properties of non integrable distributions define by collections of vector fields. It often happens that the most efficient trajectories define closed subriemannian geodesics. In this talk we will establish some of the more remarkable properties of such trajectories, with emphasis on some especially tractable situations in which the manifold admits the structure of a Riemann symmetric space with the subriemannian structure being “matched” to the structure of the symmetric space in an obvious way. We also show that the geodesic sphere associated with these problems can not be differentiable and discuss the relationship between this fact and feedback stabilization.

5:00 pm in 241 Altgeld,Monday, October 7, 2013