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INFO SHEET QUEEN’S UNIVERSITY AT KINGSTON Department of Mathematics and Statistics http://www.mast.queensu.ca November 24, 2015 CALENDAR Thursday, November 26 Seminar on Free Probability and Random Matrices Friday, November 27 Time: 4:30 p.m. Place: Jeffery 110 Number Theory Seminar Friday, November 27 Time: 11:00 a.m. Place: Jeffery 422 Department Colloquium Monday, November 30 Time: 2:30 p.m. Place: Jeffery 234 Algebraic Geometry Seminar Time: 4:30 p.m. Place: Jeffery 319 Speaker: Jamie Mingo, Queen’s University Title: Second Order Cumulants of partially Transposed Matrices Abstract Attached Speaker: Ernst Kani, Queen’s University Title: The role of Hurwitz spaces in Cryptography Abstract Attached Speaker: Lin Song, Queen’s University Title: Capacity of Communication Networks Abstract Attached Speaker: Alex Molnar, Queen’s University Title: Constructing Calabi-Yau varieties Abstract Attached Items for the Info Sheet should reach Anne ([email protected]) by noon on Monday. The Info Sheet is published every Tuesday. Thursday, November 26, 4:30 p.m. Jeffery 110 Seminar on Free Probability and Random Matrices Speaker: Jamie Mingo Title: Second Order Cumulants of Partially Transposed Matrices Abstract: I will review the construction of second order cumulants and work out the semi-circular case. I will then show how to compute these for partially transposed Wishart matrices. Seminar website: http://www.mast.queensu.ca/~mingo/seminar/ Friday, November 27, 11:00 a.m. Jeffery 422 Speaker: Ernst Kani Title: The Role of Hurwitz spaces in Cryptography Number Theory Seminar Abstract: A recent result of C. Diem (2012) showed that Public Key Cryptosystems based on hyperelliptic genus 3 curves are more secure than quartic genus 3 curves. On the other hand, by using a method due to Donagi/Livne, Ben Smith showed that it is frequently possible to convert a hyperelliptic system into a quartic system, thereby making it less secure. He also gave a heuristic (based on computer data) for how often this is possible In joint work with G. Frey (Essen) we investigated the Donagi/Livne/Smith construction from the point of view of Hurwitz spaces (which classify curve covers) and were thus able to give a theoretical explanation of Smith's heuristic. In this talk I will first give some basic facts about security of Cryptosystems, and then explain how the Donagi/Livne/Smith construction relates to curve covers and hence to Hurwitz spaces. Friday, November 27, 2:30 p.m. Jeffery 234 Speaker: Lin Song Title: Capacity of Communication Networks Department Colloquium Abstract: Network information theory deals with the fundamental limits of communication networks and their corresponding achievable coding schemes. It extends Shannon's fundamental theorems for point-to-point communication to the general multiuser setting. Although the theory is far from complete, many elegant results have been developed. In this talk, some of these results will be presented. We start from Shannon's capacity theorem for point-to-point communication channels, and then we discuss pointto-point communication with feedback, followed by discussions on multiple access channels, broadcast channels and new preliminary results for two-way networks. Monday, November 30, 4:30 p.m. Jeffery 319 Speaker: Alex Molnar Title: Constructing Calabi-Yau varieties Algebraic Geometry Seminar Abstract: After the inception of (the conjectural) string theory, Calabi-Yau varieties have become very interesting to both mathematicians and physicists, in particular, Calabi-Yau threefolds. Unfortunately, they are incredibly difficult to study in full generality. We will discuss a method to construct families of Calabi-Yau varieties from families of smaller dimensional Calabi-Yau varieties, how these families are particularly amenable to study, and the importance of this construction in string theory.