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, 3:00pm4:00pm
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 periodindex 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, 2:30pm3:30pm
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, 4:00pm5:00pm
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, 4:00pm5:00pm
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, 3:30pm4:30pm
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, 3:00pm4:00pm
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 DAGexchangeability. 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 AldousHoover 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 finegrained 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
AustinPanchenko 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, 4:00pm5:00pm
Abstract
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U. Bath

Wed 18 Sep 2019, 3:00pm
Probability Seminar

TBA

Wed 18 Sep 2019, 3:00pm4:00pm
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, 3:00pm4:00pm
Abstract
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UBC Math

Fri 4 Oct 2019, 3:00pm
Department Colloquium
ESB 2012

TBA

ESB 2012
Fri 4 Oct 2019, 3:00pm4:00pm
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Cornell University

Wed 16 Oct 2019, 4:00pm
Probability Seminar

TBA

Wed 16 Oct 2019, 4:00pm5:00pm
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, 3:00pm4:00pm
Abstract
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UBC Math

Fri 25 Oct 2019, 3:00pm
Department Colloquium
ESB 2012

TBA

ESB 2012
Fri 25 Oct 2019, 3:00pm4:00am
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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, 3:00pm4:00pm
Abstract
A link to be provided later.
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Note for Attendees
Refreshments will be served at 2:30 p.m. in ESB 4133 (Lounge).