Mathematics Dept.
  Events
University of Melbourne
Wed 19 Jun 2019, 3:00pm
Topology and related seminars
ESB 4133
On the cohomology and Chow ring of BPGLn(C)
ESB 4133
Wed 19 Jun 2019, 3:00pm-4:00pm

Abstract

The classifying space of the nth projective unitary group, BPUn, is a fundamental mathematical object. However, unlike its close cousins BUn, BSUn, etc., surprisingly little has been known to its cohomology. I will briefly introduce the roles of BPUn in the study of the topological period-index problem and anomalies in theoretical physics, and present recent progresses on the computation of its cohomology.
In the context of algebraic geometry, BPGLn, the classifying stack of the projective linear group PGLn, is an analog of BPUn, while the theory of Chow rings plays a similar role as singular cohomology. I will point out where the above computation pass to the Chow ring of BPGLn.
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UNiversity of Hong Kong
Mon 8 Jul 2019, 2:30pm SPECIAL
Algebraic Geometry Seminar
PIMS Lounge
TBA
PIMS Lounge
Mon 8 Jul 2019, 2:30pm-3:30pm

Abstract

 TBA
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Scuola Normale Superiore
Mon 8 Jul 2019, 4:00pm SPECIAL
Algebraic Geometry Seminar
PIMS Lounge
The Chow ring of the stack of stable curves of genus 2
PIMS Lounge
Mon 8 Jul 2019, 4:00pm-5:00pm

Abstract

 
There is by now an extensive theory of rational Chow rings of moduli spaces of smooth curves. The integral version of these Chow rings is not as well understood. I will survey what is known. In the last part of the talk I will discuss the Chow ring of the stack of stable curves of genus 2, which has been recently calculated by Eric Larson. I will present a different approach to the calculation, which offers an interesting point of view on stack of stable curves of genus 2. This part is joint work with Andrea Di Lorenzo.
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Dartmouth College, Hanover, NH, USA
Tue 9 Jul 2019, 4:00pm
Institute of Applied Mathematics
ICICS X836
Seminar: Permutons
ICICS X836
Tue 9 Jul 2019, 4:00pm-5:00pm

Abstract

We know that large random combinatorial structures (e.g., graphs, tilings, Ising configurations) with given parameters tend to look alike.  But what do they look like?

In the case of permutations, we can in some cases answer this question with the help of limit structures called “permutons,” together with a variational principle. We’ll present some examples, showing very nice apparent behavior and uncovering some intriguing contrasts with the case of graphs and their limit structures (graphons).

This is joint work with Rick Kenyon, Dan Kral’ and Charles Radin.
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Zhejiang University
Thu 5 Sep 2019, 3:30pm
Diff. Geom, Math. Phys., PDE Seminar
TBA
TBA
TBA
Thu 5 Sep 2019, 3:30pm-4:30pm

Abstract

 
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KAIST
Wed 11 Sep 2019, 3:00pm
Probability Seminar
TBA
A Generalization to DAGs for Hierarchical Exchangeability
TBA
Wed 11 Sep 2019, 3:00pm-4:00pm

Abstract

 

Motivated by problems in Bayesian nonparametrics and

probabilistic programming discussed in Staton et al. (2018), we

present a new kind of partial exchangeability for random arrays which

we call DAG-exchangeability. In our setting, a given random array is

indexed by certain subgraphs of a directed acyclic graph (DAG) of

finite depth, where each nonterminal vertex has infinitely many

outgoing edges. We prove a representation theorem for such arrays

which generalizes the Aldous-Hoover representation theorem.

 

In the case that the DAGs are finite collections of certain rooted

trees, our arrays are hierarchically exchangeable in the sense of

Austin and Panchenko (2014), and we recover the representation theorem

proved by them. Additionally, our representation is fine-grained in

the sense that representations at higher levels of the hierarchy are

also available. This latter feature is important in applications to

probabilistic programming, thus offering an improvement over the

Austin-Panchenko representation even for hierarchical exchangeability.

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University of Washington
Tue 17 Sep 2019, 4:00pm
Discrete Math Seminar
ESB 4127
TBA
ESB 4127
Tue 17 Sep 2019, 4:00pm-5:00pm

Abstract


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U. Bath
Wed 18 Sep 2019, 3:00pm
Probability Seminar
TBA
Wed 18 Sep 2019, 3:00pm-4:00pm

Abstract

 
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U. Bath
Fri 20 Sep 2019, 3:00pm
Department Colloquium
ESB 2012
Rising Stars Colloquium - TBA
ESB 2012
Fri 20 Sep 2019, 3:00pm-4:00pm

Abstract

 

Note for Attendees

Refreshments will be served at 2:30 p.m. in ESB 4133 (Lounge).
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UBC Math
Fri 4 Oct 2019, 3:00pm
Department Colloquium
ESB 2012
TBA
ESB 2012
Fri 4 Oct 2019, 3:00pm-4:00pm
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Cornell University
Wed 16 Oct 2019, 4:00pm
Probability Seminar
TBA
Wed 16 Oct 2019, 4:00pm-5:00pm

Abstract

 
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Cornell University
Fri 18 Oct 2019, 3:00pm
Department Colloquium
ESB 2012
(PIMS/UBC distinguished colloquium) TBA
ESB 2012
Fri 18 Oct 2019, 3:00pm-4:00pm

Abstract

 

Note for Attendees

Refreshments will be served at 2:30 p.m. in ESB 4133 (Lounge).
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UBC Math
Fri 25 Oct 2019, 3:00pm
Department Colloquium
ESB 2012
TBA
ESB 2012
Fri 25 Oct 2019, 3:00pm-4:00am
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Fri 15 Nov 2019, 3:00pm
Department Colloquium
ESB 2012
(reserved for PIMS UBC Mathematical Sciences Young Faculty Award)
ESB 2012
Fri 15 Nov 2019, 3:00pm-4:00pm

Abstract

A link to be provided later.
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