
Mon 2 Mar 2015, 1:00pm
Math Education Research Reading
MATX1118

Communities in university mathematics by Biza, Jaworski and Hemmi

MATX1118
Mon 2 Mar 2015, 1:00pm2:00pm
Abstract
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UBC Mathematics

Mon 2 Mar 2015, 3:00pm
Institute of Applied Mathematics
LSK 460

Stochastic domain decomposition for parallel grid generation

LSK 460
Mon 2 Mar 2015, 3:00pm4:00pm
Abstract
In this talk a method for the parallel generation of adaptive meshes using stochastic domain decomposition is presented. The method rests on numerically evaluating the stochastic representation of the exact solution of a linear elliptic or linear parabolic mesh generator for generating the mesh at the interfaces of the subdomains. Unlike traditional domain decomposition, this method hence does not require iteration on the subdomains or optimization of the transmission conditions to generate adaptive meshes over the entire domain. We show the generation of adaptive meshes for prescribed mesh density functions and study the scaling properties of the algorithm. A few physical examples for the parallel generation of adaptive meshes for Burgers equation and the shallowwater equations are presented. This is joint work with Ronald Haynes and Emily Walsh.
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UBC

Mon 2 Mar 2015, 3:10pm
CRG Geometry and Physics Seminar
ESB 4127

Dgmanifolds as derived manifolds

ESB 4127
Mon 2 Mar 2015, 3:10pm4:10pm
Abstract
Given two smooth maps of manifolds f:M \to L and g:N \to L, if they are not transverse, the fibered product M \times_L N may not exist, or may not have the correct cohomological properties. In the world of derived manifolds, such a fibered product always exists as a smooth object, regardless of transversality. In this talk we will describe recent progress of ours with D. Roytenberg on giving an accessible geometric model for derived manifolds using differential graded manifolds.
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UBC

Mon 2 Mar 2015, 4:00pm
Discrete Math Seminar
ESB 4127

Spectrum in Simplicial Complexes

ESB 4127
Mon 2 Mar 2015, 4:00pm5:00pm
Abstract
Ramanujan graphs are kregular graphs admitting optimal connectivity properties (namely, optimal expanders). Infinite families of such graphs were first constructed by Lubotzky, Phillips and Sarnak in 1988 by relating the spectrum of a graph with certain representations of GL_2(Q_p). These ideas were generalized to simplical complexes by Lubotzky, Samuels and Vishne in 2005.
We will present a further generalization, showing that there is a natural way to relate spectral properties of simplicial complexes with certain representations of groups acting on their universal covers. Several results of this connection will be discussed. In particular, we strengthen the spectral properties of the complexes constructed by LSV. (Roughly speaking, we show that the complexes constructed by LSV have "optimal spectrum in all dimensions".)
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Stanford University

Tue 3 Mar 2015, 3:30pm
Diff. Geom, Math. Phys., PDE Seminar
ESB 2012

On the topology and index of minimal surfaces

ESB 2012
Tue 3 Mar 2015, 3:30pm4:30pm
Abstract
We show that for an immersed twosided minimal surface in R^3, there is a lower bound on the index depending on the genus and number of ends. Using this, we show the nonexistence of an embedded minimal surface in R^3 of index 2, as conjectured by Choe. Moreover, we show that the index of an immersed twosided minimal surface with embedded ends is bounded from above and below by a linear function of the total curvature of the surface. (This is joint work with Otis Chodosh)
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Bilkent University and McMaster Univerisity

Wed 4 Mar 2015, 3:15pm
Topology and related seminars
ESB 4133

Finite group actions on homotopy spheres

ESB 4133
Wed 4 Mar 2015, 3:15pm4:15pm
Abstract
We are interested in classifying all finite groups which can act on a finite CWcomplex homotopy equivalent to a sphere, such that all isotropy subgroups are rank one groups, i.e., they do not include Z/pxZ/p for any prime p. The equivalent question for free actions (all isotropy subgroups are trivial) has been answered completely by the works of P.A. Smith and R. Swan. For actions with rank one isotropy, we give a list of group theoretical conditions which guarantee the existence of such actions. Some of these conditions are necessary conditions depending on assumptions on fixed point subspaces. This is a joint work with Ian Hambleton.
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Thu 5 Mar 2015, 3:30pm
Number Theory Seminar
room MATH 126


room MATH 126
Thu 5 Mar 2015, 3:30pm4:30pm
Abstract
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Mathematics, University of Bath

Fri 6 Mar 2015, 4:00pm
SPECIAL
Institute of Applied Mathematics
Canfor Policy Rm 1600, SFU Harbour Centre, Downtown Vancouver

Data Assimilation and Adaptivity

Canfor Policy Rm 1600, SFU Harbour Centre, Downtown Vancouver
Fri 6 Mar 2015, 4:00pm5:00pm
Abstract
Data assimilation is the process of systematically including (often noisy) data into a forecast. It is now widely used in numerical weather prediction and its positive impact on the accuracy of weather forecasts is unquestionable. Indeed improvements in our ability to forecast the weather over the last decade are a reflection on the increasing volume of data available, improved computational methods and (significantly) much improved algorithms for incorporating this data into the forecast. However, many problems remain, including dealing with the sheer volume of the data and the inherent complexity of the weather and climate, understanding the effects of data and model error, and of reducing spurious correlations between the data and the forecast.
In this talk I will give a survey of various techniques that are used operationally to implement data assimilation procedures in weather (and climate) forecasting including the Ensemble Kalman Filter, and the 4DVar method.
I will discuss their various advantages and disadvantages, the nature of the errors and ways to minimise these. In particular I will show that the use of adaptive numerical methods can significantly improve the performance
of the 4DVar method. Hopefully I will show that used carefully Data Assimilation techniques can significantly improve our ability to forecast the weather of Planet Earth.
Joint work with Mike Cullen and Chiara Piccolo at the Met Office.
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UBC

Mon 9 Mar 2015, 3:00am
CRG Geometry and Physics Seminar
ESB 4127

The DonaldsonThomas theory of K3xE via motivic and toric methods

ESB 4127
Mon 9 Mar 2015, 3:00am4:00pm
Abstract
DonaldsonThomas invariants are fundamental deformation invariants of CalabiYau threefolds. We describe a recent conjecture of Oberdieck and Pandharipande which predicts that the (three variable) generating function for the DonaldsonThomas invariants of K3xE (the product of a K3 surface and an elliptic curve) is given by the reciprocal of the Igusa cusp form of weight 10. For each fixed K3 surface of genus g, the conjecture predicts that the corresponding (two variable) generating function is given by a particular meromorphic Jacobi form. We prove the conjecture for K3 surfaces of genus 0 and genus 1. Our computation uses a new technique which mixes motivic and toric methods.
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Colorado State University

Tue 10 Mar 2015, 4:00pm
Discrete Math Seminar
TBA

TBA

TBA
Tue 10 Mar 2015, 4:00pm5:00pm
Abstract
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University of Washington

Wed 11 Mar 2015, 3:10pm
Probability Seminar
ESB 2012

The frog model on trees

ESB 2012
Wed 11 Mar 2015, 3:10pm4:00pm
Abstract
Fix a graph G and place some number (random or otherwise) of sleeping frogs at each site, as well as one awake frog at the root. Set things in motion by having awake frogs perform independent simple random walk, waking any "sleepers" they encounter. Say the model is recurrent if the root is a.s. visited by infinitely many frogs and otherwise transient. When G is the rooted dary tree with onefrogpersite we prove a phase transition from recurrence to transience as d increases. Alternatively, for fixed d with Poi(m)frogspersite we prove a phase transition from transience to recurrence as m increases. The proofs use two different recursions and two different versions of stochastic domination. Several open problems will be discussed. Joint with Christopher Hoffman and Tobias Johnson.
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Osaka University

Wed 11 Mar 2015, 3:15pm
Topology and related seminars
ESB 4133

PseudoAnosovs with small dilatations in the hyperelliptic handlebody groups and spherical Hilden groups

ESB 4133
Wed 11 Mar 2015, 3:15pm4:15pm
Abstract
This is a joint work with Susumu Hirose. We consider pseudoAnosov elements of the mapping class groups on orientable surfaces. We are interested in a numerical invariant of pseudoAnosovs, called the dilatation. The logarithm of the dilatation of a pseudoAnosov mapping class is called the entropy. If we fix a surface, then the set of dilatations of pseudoAnosovs defined on the surface is closed and discrete. In particular we can talk about a minimum of any subset of dilatations defined on the surface in question.
Penner proved that the minimal entropy of pseudoAnosovs defined on a closed surface of genus g behaves like 1/g. Later Hironaka proved that the minimal entropy of pseudoAnosovs in the handlebody subgroup on a closed surface of genus $g$ also behaves like 1/g. We prove that the the minimal entropy of the hyperelliptic handlebody sugbroup of genus g has the same asymptotic behavior. (Our examples of pseudoAnosovs improve the upper bound of the minimal entropy of the handlebody sugbroup given by Hironaka.) To do this, we study the spherical Hilden subgroup of the mapping class group defined on a sphere with 2n punctures, and we construct a sequence of pseudoAnosovs with small dilatations in the spherical Hilden subgroups.
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Colorado State University

Thu 12 Mar 2015, 3:30pm
Number Theory Seminar
room MATH 126

Local heuristics and exact formulas for elliptic curves over finite fields

room MATH 126
Thu 12 Mar 2015, 3:30pm4:30pm
Abstract
An isogeny class of elliptic curves over a finite field is determined by a quadratic Weil polynomial. Gekeler has given a beautiful product formula, purely in terms of congruence considerations involving that polynomial, for the size of such an isogeny class; an equidistribution hypothesis too strong to be true apparently calculates this cardinality.
I will give a new, transparent explanation, worked out with Julia Gordon, for this phenomenon. It turns out that Gekeler's formula computes an adelic orbital integral which, thanks to work of Langlands and Kottwitz, visibly calculates the desired quantity.
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Brown University

Fri 13 Mar 2015, 3:00pm
Department Colloquium
ESB 2012 (PIMS)

The mathematics of latticebased cryptography (PIMSUBC Distinguished Colloquium)

ESB 2012 (PIMS)
Fri 13 Mar 2015, 3:00pm4:00pm
Abstract
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Imperial College

Mon 16 Mar 2015, 3:10pm
CRG Geometry and Physics Seminar
ESB4127

Mirror Symmetry and the Classification of Fano Manifolds

ESB4127
Mon 16 Mar 2015, 3:10pm4:10pm
Abstract
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UBC

Tue 17 Mar 2015, 2:00pm
SPECIAL
Topology and related seminars
ESB 4133


ESB 4133
Tue 17 Mar 2015, 2:00pm3:00pm
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Mathematics, UBC

Thu 19 Mar 2015, 12:30pm
SPECIAL
One Time Event
Room 203 of the Graduate Student Centre (6371 Crescent Rd.), UBC

Doctoral Exams

Room 203 of the Graduate Student Centre (6371 Crescent Rd.), UBC
Thu 19 Mar 2015, 12:30pm2:30pm
Details
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Thu 19 Mar 2015, 3:30pm
Number Theory Seminar
room MATH 126


room MATH 126
Thu 19 Mar 2015, 3:30pm4:30pm
Abstract
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UBC and Beijing Institute of Technology

Thu 19 Mar 2015, 4:30pm
Symmetries and Differential Equations Seminar
Math 125

Symmetry analysis and conservation laws for fractional order partial differential equations Part II

Math 125
Thu 19 Mar 2015, 4:30pm5:30pm
Abstract
In this second talk, we again consider symmetries and conservation laws of FPDEs equation with RiemannLiouville derivatives. Within the framework of Lie group theory, we extend Lie group analysis to solve problems involving FPDEs. Finally, we give further examples to illustrate applications of the methods. Some open questions will be discussed.
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UBC

Fri 20 Mar 2015, 3:00pm
Department Colloquium
LSK 200 (Note the special location)

Graduate Research Award Lecture

LSK 200 (Note the special location)
Fri 20 Mar 2015, 3:00pm4:00pm
Abstract
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Mathematics, UBC

Fri 20 Mar 2015, 4:00pm
SPECIAL
One Time Event
Room 203 of the Graduate Student Centre (6371 Crescent Rd), UBC

Doctoral Exams

Room 203 of the Graduate Student Centre (6371 Crescent Rd), UBC
Fri 20 Mar 2015, 4:00pm6:00pm
Details
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Mathematics, UBC

Tue 24 Mar 2015, 12:00pm
SPECIAL
One Time Event
Room 126 of the Mathematics Bldg.

Doctoral Exams

Room 126 of the Mathematics Bldg.
Tue 24 Mar 2015, 12:00pm2:00pm
Details
TBA
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Korea Institute for Advanced Study

Tue 24 Mar 2015, 3:30pm
Diff. Geom, Math. Phys., PDE Seminar
ESB 2012

New characterizations of the catenoid and helicoid

ESB 2012
Tue 24 Mar 2015, 3:30pm4:30pm
Abstract
Bernstein and Breiner found a characterization of the catenoid that the area of a minimal annulus in a slab is bigger than that of the maximally stable catenoid in the same slab. We give a simpler proof of their theorem and extend the theorem to some minimal surfaces with genus (joint work with Benoit Daniel). New characterizations of the helicoid recently proved by Eunjoo Lee will be also presented.
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UBC

Wed 25 Mar 2015, 3:15pm
Topology and related seminars
ESB 4133


ESB 4133
Wed 25 Mar 2015, 3:15pm4:15pm
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UBC

Thu 26 Mar 2015, 3:30pm
Number Theory Seminar
room MATH 126

TBA

room MATH 126
Thu 26 Mar 2015, 3:30pm4:30pm
Abstract
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UBC

Fri 27 Mar 2015, 3:00pm
Department Colloquium
ESB 2012

CRMFieldsPIMS prize lecture: algebraic stacks and the inertia operator

ESB 2012
Fri 27 Mar 2015, 3:00pm4:00pm
Abstract
Motivated by subtle questions in DonaldsonThomas theory, we study the spectrum of the inertia operator on the Grothendieck module of algebraic stacks. We hope to give an idea of what this statement means. Along the way, we encounter some elementary, but apparently new, questions about finite groups and matrix groups. Prerequisites for this talk: a little linear algebra, and a little group theory.
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Mathematics, UBC

Mon 30 Mar 2015, 9:00am
SPECIAL
One Time Event
Room 203 of the Graduate Student Centre (6371 Crescent Rd), UBC

Doctoral Exams

Room 203 of the Graduate Student Centre (6371 Crescent Rd), UBC
Mon 30 Mar 2015, 9:00am11:00am
Details
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Mathematics Manchester

Mon 30 Mar 2015, 3:00pm
SPECIAL
Institute of Applied Mathematics
LSK 460

Modelling plant cell and tissue growth

LSK 460
Mon 30 Mar 2015, 3:00pm4:00pm
Abstract
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Felipe Garcia Ramos Aguilar
Mathematics, UBC

Tue 31 Mar 2015, 12:30pm
SPECIAL
One Time Event
Room 203 of the Graduate Student Centre (6371 Crescent Road), UBC

Doctoral Exams

Room 203 of the Graduate Student Centre (6371 Crescent Road), UBC
Tue 31 Mar 2015, 12:30pm2:30pm
Details
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Fri 10 Apr 2015, 3:00pm
Department Colloquium
LSK 200


LSK 200
Fri 10 Apr 2015, 3:00pm4:00pm
Abstract
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UCLA

Thu 21 May 2015, 3:30pm
Number Theory Seminar
room MATH 126

TBA

room MATH 126
Thu 21 May 2015, 3:30pm4:30pm
Abstract
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Fri 11 Sep 2015, 3:00pm
Department Colloquium

reserved

Fri 11 Sep 2015, 3:00pm4:00pm
Abstract
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Princeton University

Fri 23 Oct 2015, 3:00pm
SPECIAL
Department Colloquium / PIMS Seminars and PDF Colloquiums
ESB2012

TBAPIMS/UBC Distinguished Colloquium

ESB2012
Fri 23 Oct 2015, 3:00pm4:00pm
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Note for Attendees
Note SFU downtown venue. Reception at 3:30 pm (light refreshments).