# Queen's University - Department of Mathematics and Statistics

 Tuesday, April 4 Dynamics Seminar Time: 3.30 p.m. Place: Jeffery 422 Speaker: Julian Christopher, Queen’s University Title: The Poincaré-Bendixson Theorem Abstract Attached Wednesday, April 5 Curves Seminar Time: 3:30 pm. Place: Jeffery 422 Speaker: Mike Roth Title: Stable points and the one-parameter criterion Abstract Attached Thursday, April 6 Math Club Time: 5:30 p.m. Place: Jeffery 118 Speaker: Thomas Barthelmé Title: The Mathematics of Juggling Abstract Attached Friday, April 7 Number Theory Seminar Time: 10:30 a.m. Place: Jeffery 422 Speaker: Yu-Ru Liu, University of Waterloo Title: The circle method in function fields Abstract Attached Friday, April 7 Department Colloquium Time: 2:30 p.m. Place: Jeffery 234 Speaker: Fabrice Baudouin, University of Connecticut Title: Ricci curvature lower bounds in sub-Riemannian Abstract Attached Monday, April 10 Ph.D. Thesis Defense Time: 10:00 a.m. Place: Jeffery 521 Ph.D. Student: Peng-Jie Wong Title: Character Theory and Artin L-functions Supervisor: Ram Murty Wednesday, April 19 Ph.D. Thesis Defense Time: 1:00 p.m. Place: Jeffery 521 Ph.D. Student: Yinzheng Gu Title: Non-commutative Independences for Paris of Faces Supervisors: Jamie Mingo and Serban Belinschi

Items for the Info Sheet should reach Anne ( burnsa@queensu.ca) by noon on Monday. The Info Sheet is published every Tuesday.

CALCULATOR EXAM POLICY , the official calculator is a Casio fx-991, or one with a blue sticker as issued by School of Business. All exam cover pages must only refer to these calculators only; any other exam cover, including other calculators (ie gold sticker) will not be accepted by the exams office. Proctors are going to be instructed to be less lenient with calculators that aren’t Casio fx-991 (or blue sticker from COMM), and will likely to be taking them away.

Tuesday, April 4, 3:30 p.m. Jeffery 422 - Dynamics Seminar

Speaker: Julian Christopher

Title: The Poincaré-Bendixson Theorem

Abstract: The Poincaré-Bendixson theorem completely describes the long-term behavior of a flow on (any open set of) the 2-sphere. Moreover, the basic ideas used in the proof can be very useful in similar contexts. We will present a proof of the theorem.

Wednesday, April 5, 3:30 p.m. Jeffery 422 - Curves Seminar

Speaker: Mike Roth

Title: Stable points and the one-parameter criterion

Abstract: We will discuss stability of points on with respect to a G-linearized line bundle, and the one-parameter criterion for semi-stability and stability.

Thursday, April 6, 5:30 p.m. Jeffery 118 - Math Club

Speaker: Thomas Barthelmé

Title: The Mathematics of Juggling

Abstract: In this talk, we will see how to code a juggling pattern using periodic sequences. Then, we will try to answer some, or all, of the following questions: Given a periodic sequence, how can I tell if it corresponds to a juggling pattern? And if it does, how many balls do I need to juggle it? Finally, how many different juggling patterns of period $p$ can one do with $b$ balls?

One thing we will not try to do in this talk, due to lack of expertise, is teach anyone how to actually juggle any of these patterns.

Friday, April 7, 10:30 a.m. Jeffery 422 - Number Theory Seminar

Speaker: Yu-Ru Liu

Title: The circle method in function fields

Abstract: We will introduce the circle method in function fields, and then apply it to study Waring's problem and Vinogradov's mean value theorem for polynomials. We will address possible problems arising in a positive characteristic setting. This is joint work with T. Wooley, W. Kuo and X. Zhao.

Friday, April 7, 2:30 p.m. Jeffery 234 - Department Colloquium

Speaker: Fabrice Baudouin

Title: Ricci curvature lower bounds in sub-Riemannian geometry

Abstract: In this talk, we will review the recent developments in the geometric analysis of the sub-Riemannian manifolds in which generalized notions of Ricci curvature lower bounds have been defined.

### Contact Info

 Department of Math & Stats Jeffery Hall, 48 University Ave. Kingston, ON Canada, K7L 3N6 Phone: (613) 533-2390 Fax: (613) 533-2964 mathstat@mast.queensu.ca Office Hours: 8:30am-12:00pm & 1:00pm-4:30pm