Infosheet (November 14th, 2017) 
Queen's University  Department of Mathematics and Statistics 
Wednesday, November 15 
Number Theory Seminar Time: 1:30 p.m. Place: Jeffery 319 
Speaker: PengJie Wong, University of Lethbridge Title: Base change and the Langlands reciprocity conjecture Abstract Attached 
Thursday, November 16 
Seminar in Free Probability and Random Matrices Time: 3:30 p.m. Place: Jeffery 222 
Speaker: PeiLun Tseng, Queen’s University Title: Free independence of type B Abstract Attached 
Friday, November 17 
Department Colloquium Time: 2:30 p.m. Place: Jeffery 234 
Speaker: Mokshay Madiman, University of Delaware Title: The convexifying effect of Minkowski summation Abstract Attached 
Monday, November 20 
Special Colloquium Time: 4:30 p.m. Place: Jeffery 118 
Speaker: Alex Wright, Stanford University Title: Dynamics, geometry, and the moduli space of Riemann surfaces Abstract Attached 
Wednesday, November 22

Special Colloquium Time: 3:30 p.m. Place: Jeffery 234 
Speaker: Jenny Wilson Title: Stability in ordered configuration spaces Abstract Attached 
Friday, November 24 
Ph.D. Thesis Defense Time: 10:00 a.m. Place: Jeffery 521 
Ph.D. Student: Aaron Springford Title: Spectral analysis of time series with latent and irregular times Supervisors: D. Thomson and G. Takahara 
Items for the Info Sheet should reach Anne ( burnsa@queensu.ca) by noon on Monday. The Info Sheet is published every Tuesday.
Wednesday, November 15, 1:30 p.m. Jeffery 319  Number Theory Seminar
Speaker: PengJie Wong
Title: Base change and the Langlands reciprocity conjecture
Abstract: In light of Artin reciprocity, Langlands enunciated a reciprocity conjecture asserting that any complex Galois representation is automorphic. Around 1980, Langlands established certain cyclic base change and proved his reciprocity conjecture for 2dimensional Galois representations with projective image isomorphic to $A_4$. In this talk, we will try to give a motivation of the Langlands reciprocity conjecture and discuss its relation to base change. If time permits, we will explain how the conjectural base change leads to Langlands reciprocity for all 3dimensional Galois representations with solvable image.
This is a joint work with M. Ram Murty and V. Kumar Murty
Thursday, November 16, 3:30 p.m. Jeffery 222
Seminar in Free Probability and Random Matrices
Speaker: PeiLun Tseng
Title: Free independence of type B
Abstract: We will continue our discussion of type B Rtransform. Then we are going to introduce the free independence of type B, and establish the relation between type B freeness and vanishing mixed cumulants in type B.
Seminar website: www.mast.queensu.ca/~mingo/seminar/
Friday, November 17, 2:30 p.m. Jeffery 234  Department Colloquium
Speaker: Mokshay Madiman
Title: The convexifying effect of Minkowski summation
Abstract: For a compact subset A of R^d, let A(k) be the Minkowski sum of k copies of A, scaled by 1/k. By a 1969 theorem of Emerson, Folkmann, Greenleaf, Shapley and Starr, A(k) approaches the convex hull of A in Hausdorff distance as k goes to infinity; this fact has important applications in a number of areas including mathematical economics. A few years ago, the speaker conjectured that the volume of A(k) is nondecreasing in k, or in other words, that when the volume deficit between the convex hull of A and A(k) goes to 0, it actually does so monotonically. While this conjecture holds true in dimension 1 (as independently observed by F. Barthe), we show that it fails in dimension 12 or greater. Then we consider whether one can have monotonicity of convergence of when nonconvexity is measured in alternate ways. Our main positive result is that Schneider’s index of nonconvexity of A(k) converges monotonically to 0 as k increases; even the convergence does not seem to have been known before. As a byproduct, we also obtain optimal rates of convergence. We also obtain analogous results for the Hausdorff distance to the convex hull, as well as for the inner radius, and demonstrate applications to discrepancy theory. Joint work with Matthieu Fradelizi (MarnelaVallée), Arnaud Marsiglietti (CalTech), and Artem Zvavitch (Kent State).
Monday, November 20, 4:30 p.m. Jeffery 118  Special Colloquium
Speaker: Alex Wright
Title: Dynamics, geometry, and the moduli space of Riemann surfaces
Abstract: The moduli space of Riemann surfaces of fixed genus is one of the hubs of modern mathematics and physics. We will tell the story of how simple sounding problems about polygons, some of which arose as toy models in physics, became intertwined with problems about the geometry of moduli space, and how the study of these problems in Teichmuller dynamics lead to connections with homogeneous spaces, algebraic geometry, dynamics, and other areas. The talk will mention joint works with Alex Eskin, Simion Filip, Curtis McMullen, Maryam Mirzakhani, and Ronen Mukamel.
Wednesday, November 22, 3:30 p.m. Jeffery 234  Special Colloquium
Speaker: Jenny Wilson
Title: Stability in ordered configuration spaces
Abstract: The ordered configuration space F_k(M) of a manifold M is the space of ordered ktuples of distinct points in M. For a fixed manifold M, as k increases, we might expect the topology of these configuration spaces to become increasingly complicated. Church and others showed, however, that when M is connected and open, there is a representationtheoretic sense in which these spaces stabilize. In this talk, I will explain these stability patterns, and describe higherorder stability phenomena established in recent work joint with Jeremy Miller. This project was inspired by workinprogress of GalatiusKupersRandalWilliams.