Events
All upcoming and recent events from the past six months:
Title: Sequence representation in the brain, a brain imaging study
Speaker: Danesh Shahnazian, University of Victoria
Date and time:
17 Apr 2018,
2:30pm -
3:20pm
Location: DTB A104
Event type: Statistics seminar
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The neural correlates of sequence representation has been of interest to neuroscientists for some time. While past studies have employed univariate methods to study sequence production, many scientists now agree that this phenomenon can be better studied via multivariate methods. In this study, we used a multivariate statistical technique called representational similarity analysis to analyze brain imaging data recorded as our research participants engaged in performing four different sequences of actions. The results show that the medial prefrontal cortex a brain area located in the medial frontal lobe of the brain is involved in sequence production. Our study demonstrates the utility of representation similarity analysis in the analysis of sequence production.
Title: Some results in Ergodic Optimization
Speaker: Juliano dos Santos Gonschorowski, University of Victoria
Date and time:
16 Apr 2018,
3:30pm -
4:20pm
Location: DSB C126
Event type: Dynamics seminar
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Abstract: In this seminar we will talk about variations of the following
problem: Given the functional P:M(T)\rightarrow \R, P(\mu)= \int f d\mu,
defined over the set M(T) of Borel invariant probabilities for some
dynamic T:X \rightarrow X, what are the measures that maximize the
functional? We also will talk about the motivation of that problem, some
classical and new results on this subject.
Title: Bootstrap Calibration for Empirical Likelihood Methods
Speaker: Peng Tang, University of Victoria
Date and time:
13 Apr 2018,
4:00pm -
5:00pm
Location: CLE B017
Event type: Graduate dissertations
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The Final Oral Examination for the Degree of
Master of Science (Department of Mathematics & Statistics)
Peng TANG
2016 Xiamen University B.Econ
“Bootstrap Calibration for Empirical Likelihood Methods”
April 13th, 2018 4pm
CLE B017
Supervisory Committee:
Dr. Mary Lesperance, Department of Mathematics & Statistics, UVic (Co-supervisor)
Dr. Min Tsao, Department of Mathematics & Statistics, UVic (Co-supervisor)
Chair of Oral Examination:
Dr. Xuekui Zhang, Department of Mathematics & Statistics, UVic
Title: Comparisons of Outlier Detection Methods in Regression Model with Economic Data
Speaker: Yunfan Ma, University of Victoria
Date and time:
13 Apr 2018,
10:00am -
11:00am
Location: Clearihue Building Room B315
Event type: Graduate dissertations
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The Final Oral Examination for the Degree of
Master of Science (Department of Mathematics & Statistics)
YUNFAN MA
B.Sc (University of Victoria, 2016)
“Comparisons of Outlier Detection Methods in Regression Model with Economic Data”
Friday, April 13, 2018 10:00 A.M. Clearihue Building Room B315
Supervisory Committee:
Dr. Julie Zhou, Department of Mathematics & Statistics, UVic (Supervisor)
Dr. Laura Cowen, Department of Mathematics & Statistics, UVic (Member)
Chair of Oral Examination:
Dr. Christopher Eagle, Department of Mathematics & Statistics, UVic
Title: Multivariate Frailty Models for Two Types of Recurrent Events with A Dependent Terminal Event
Speaker: Grace Li, University of Victoria
Date and time:
12 Apr 2018,
2:00pm -
3:00pm
Location: Cornett A317
Event type: Graduate dissertations
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The Final Oral Examination for the Degree of
Master of Science (Department of Mathematics & Statistics)
Zhuolin (Grace) LI
B.Sc. (Xi’an Jiaotong University, 2011)M.A. (Xi’an Jiaotong University, 2014)
“Multivariate Frailty Models for Two Types of Recurrent Events with A Dependent Terminal Event: Application to Marital Dissolution and Retirement”
Thursday, April 12, 2018 2:00 P.M. Cornett Building Room A317
Supervisory Committee:
Dr. Mary Lesperance, Department of Mathematics & Statistics, UVic (Co-supervisor)
Dr. Zheng Wu, Department of Mathematics & Statistics, Department of Sociology, UVic (Co-supervisor)
Chair of Oral Examination:
Dr. Margaret Penning, Department of Sociology, UVic
Title: Uniqueness and nondegeneracy of ground states to nonlinear scalar field equations involving the Sobolev critical exponent in the
Speaker: HIroki Kikuchi, Tsuda University
Date and time:
11 Apr 2018,
3:30pm -
4:20pm
Location: DSB C130
Event type: Applied math seminar
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Abstract:
In this talk, we consider the uniqueness and nondegeneracy of positive ground state solutions to semilinear elliptic equations with combined power-type nonlinearities involving the Sobolev critical exponent. This study is of great importance because of the resulting energy landscape and its implications for the dynamics.
We shall show that the positive radial ground state is unique and nondegenerate if the frequency is sufficiently large.
If time permits, we shall discuss about several future works.
This talk is based on a joint work with T. Akahori (Shizuoka), S. Ibrahim(Uvic), N. Ikoma(Keio), and H. Nawa(Meiji).
Title: Two projects
Speaker: Yan Xu, University of Victoria
Date and time:
10 Apr 2018,
2:30pm -
3:20pm
Location: DSB C108
Event type: Statistics seminar
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Title 1: Aggregating Analysis of Multiple Genomic Studies by Voting
Abstract 1: Aggregating analysis of multiple studies is an important research tool for studies involving genomic data. It becomes so popular in these days mainly due to two reasons. 1. The huge amount of genomic data from various past studies are available online to help researchers answer their new research questions. 2. Due to the curse of dimensionality and cost of experiments related to the whole genome biomarkers, many studies are underpowered after multiple testing adjustment. Meta-analysis, with history of more than a century, is the most popular statistical method to aggregate analyses from multiple studies. But results of meta-analysis can be misleading if some biomarkers in genomic data have some problems, or if bad studies are not excluded by the selection criteria due to undiscoverable confounding issues. To address this problem, we propose a new algorithm as an alternative to meta-analysis. A simulation study is conducted to compare the performance of our approach with meta-analysis, and show that our method is robust to the analysis of studies with abnormal signals.
Title 2: A Model-Based Clustering to Identify Disease-Associated SNPs
Abstract 2: Genome-wide association studies (GWASs) aim to detect genetic risk factors for complex human diseases by identifying disease-associated single-nucleotide polymorphisms (SNPs). The most commonly-usedGWAS method is the SNP-wise-test approach, in which an association test is performed for each SNP, and then the p-values are adjusted for multiple testing. However, this approach is often lack of power after multiple testing adjustments due to a huge number (> 1 million) of tests in GWAS. To address this problem, we propose a model-based clustering via a mixture of Bayesian hierarchical models, which could borrow information across SNPs to group SNPs to different clusters having different mean genotype levels between cases and controls. Simulation studies and real data studies showed that the proposed model-based clustering outperformed SNP-wised-test approach.
Title: Automorphisms of the shift: entropy and the dimension representation
Speaker: Scott Schmieding, Northwestern University
Date and time:
09 Apr 2018,
3:30pm -
4:20pm
Location: DSB C126
Event type: Dynamics seminar
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Abstract: For a shift of finite type $(X,\sigma)$, the automorphism group
$Aut(\sigma)$
consists of all homeomorphisms from $X$ to $X$ which commute with the
shift map $\sigma$.
The group $Aut(\sigma)$ is known to contain a rich structure, and has
been heavily studied
over the years. To analyze a particular automorphism, one may consider its
action on the
dimension group, an ordered abelian group associated to the system
$(X,\sigma)$. We
will describe what this dimension group is, and discuss relationships
between various
dynamical properties of an automorphism and its action on the associated
dimension group.
We'll focus on connections between the topological entropy of an
automorphism and spectral
data coming from its action on the dimension group, and how this relates
to an entropy
conjecture for shifts of finite type in the spirit of Shub's classical
entropy conjecture.
Title: PIMS Undergraduate Event - Twist and Turn: the Story of the Game of Hex
Speaker: Ryan Hayward, University of Alberta
Date and time:
06 Apr 2018,
3:00pm -
4:00pm
Location: David Strong Building, room C116
Event type: PIMS lectures
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(pre-lecture refreshments in DTB A514 @ 2:30 pm)
In 1942, the Danish engineer, poet, and designer Piet Hein invented a new board game and --- with a little help from his friends --- introduced it to readers of the Danish newspaper Politiken. The game became popular: within a year, 50,000 game pads sold.
In 1949 John Nash introduced the game to the Princeton math community, and in 1957 Martin Gardner passed it on to readers of Scientific American.
In this talk for a general audience, I will sketch some big moments in Hex history, ending with an outline of the ideas that make a nearly-superhuman computer Hex program tick.
---
Ryan Hayward received his B.Sc. and M.Sc. in mathematics from Queen's University (Kingston) in 1981 and 1982 and his Ph.D. in computer science from McGill University in 1987. His doctoral thesis, Two Classes of Perfect Graphs, was supervised by Vaclav Chvatal. From 1986 through 1989 he was assistant professor in the Department of Computer Science at Rutgers University, after which he held an Alexander von Humboldt fellowship at the Institute for Discrete Mathematics in Bonn for 1989-90.
From 1990 through 1992 he was assistant professor in the Department of Computing Science at Queen's University. From 1992 he was assistant and then associate professor in the Department of Mathematics and Computer Science at the University of Lethbridge, until in 1999 joining the Department of Computing Science at the University of Alberta, where he was promoted to professor in 2004.
He has supervised 13 graduate and 29 undergraduate students, some of whom later became university professors. His current research interests include algorithms for two-player games. His group (including at times Yngvi Bjornsson, Michael Johanson, Broderick Arneson, Philip Henderson, Jakub Pawlewicz, Chao Gao and Aja Huang --- later lead programmer of AlphaGo) has built the world's strongest computer Hex player, and has solved two 1-move 10x10 Hex openings and all smaller-board openings. With Bjarne Toft, he is writing a book on the history of Hex, to be published in 2018.
Many years ago, Ryan rode his bicycle from Vancouver to Lethbridge.
Download poster (PDF)
Title: Universality of the dimer model
Speaker: Gourab Ray, University Victoria
Date and time:
04 Apr 2018,
3:30pm -
4:20pm
Location: DSB C130
Event type: Applied math seminar
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Abstract: A dimer model is a model of perfect matching and is an extremely popular subject motivated from problems in statistical mechanics. In this talk, I will outline the basics of this model along with our ongoing project aimed at showing that these models exhibit a large scale universal behaviour (with respect to graphs, underlying surface or boundary conditions) in a certain sense.
Ongoing Joint work with Nathanael Berestycki and Benoit Laslier.
Title: Elliptic operators and K-Homology (part 2 of 2)
Speaker: Anna Duwenig, University of Victoria
Date and time:
04 Apr 2018,
3:30pm -
4:45pm
Location: CLE D 132
Event type: Operator theory seminar
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Abstract: Any symmetric, elliptic differential operator on a smooth
manifold gives rise to a K-Homology class for said manifold. In these
talks, we will first provide the necessary background to understand this
Theorem by introducing Kasparov's K-Homology and the notion of
differential operators. We will then sketch a proof for the case of
compact manifolds.
Title: Ergodic optimization, bounds, and semidefinite programming
Speaker: David Goluskin, University of Victoria
Date and time:
03 Apr 2018,
3:30pm -
4:20pm
Location: DSB C130
Event type: Dynamics seminar
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Abstract: I will discuss the estimation of infinite-time averages in
discrete and continuous dynamical systems. In particular, I will consider
upper bounds on the maximum such averages among all initial conditions --
in other words, the maximum expectations among invariant measures. Often
the search for a minimal upper bound can be posed as a polynomial
optimization problem, which in turn can be formulated as a semidefinite
program. The latter is a standard type of convex optimization problem that
can be solved with computer assistance.
Title: Gas meters and the Rao-Blackwell Theorem
Speaker: Mary Lesperance, University of Victoria
Date and time:
03 Apr 2018,
2:30pm -
3:20pm
Location: DSB C108
Event type: Statistics seminar
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When teaching the Rao-Blackwell Theorem in Stat450 this term, I was reminded that I encountered the theorem while working on a Statistical consulting contract which involved assessing the accuracy of gas meters.
The objectives of the consulting contract were: (i) to statistically evaluate Acceptance Sampling Plans used in the monitoring of household gas meter accuracy by the Ministry of Consumer and Corporate Affairs Canada, and (ii) to propose a new and fair methodology. In this seminar, I will introduce Acceptance Sampling theory and review the interesting statistical issues raised by the consulting application. En route, I will discuss a multivariate estimator used in Acceptance Sampling which was derived with the Rao-Blackwell Theorem.
Our work on this problem is published in The Canadian Journal of Statistics, the Journal of Statistical Computation(2 articles) and Simulation and Technometrics.
Title: Irreversible k- Threshold Conversion Processes on Graphs
Speaker: Jane Wodlinger, University of Victoria
Date and time:
03 Apr 2018,
1:30pm -
2:30pm
Location: Clearihue Building B017
Event type: Graduate dissertations
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Notice of the Final Oral Examination for the Degree of Doctor of Philosophy
of
JANE WODLINGER
MSc (Simon Fraser University, 2012) BSc (University of Victoria, 2009)
“Irreversible k- Threshold Conversion Processes on Graphs” Department of Mathematics and Statistics
Tuesday, April 3, 2018 1:30 P.M. Clearihue Building Room B017
Supervisory Committee:
Dr. Kieka Mynhardt, Department of Mathematics and Statistics, University of Victoria (Supervisor) Dr. Peter Dukes, Department of Mathematics and Statistics, UVic (Member)
Dr. Venkatesh Srinivasan, Department of Computer Science, UVic (Outside Member)
External Examiner:
Dr. Nancy Clarke, Mathematics and Statistics, Acadia University
Chair of Oral Examination:
Dr. Simon Devereaux, Department of History, UVic
Abstract
Given a graph G and an initial colouring of its vertices with two colours, say black and white, an irreversible k-threshold conversion process on G is an iterative process in which a white vertex becomes permanently coloured black if at least k of its neighbours are coloured black at time t − 1. A set S of vertices is an irreversible k-threshold conversion set (k-conversion set) of G if the initial colouring in which the vertices of S are black and the others are white results in the whole vertex set becoming black eventually. In the case where G is (k + 1)-regular, it can be shown that the k- conversion sets coincide with the so-called feedback vertex sets, or decycling sets.
In this dissertation we study the size, ck(G), and structure of minimum k-conversion sets in several classes of graphs, G. We examine conditions that lead to equality and inequality in existing bounds on ck(G) for k- and (k+1)-regular graphs. Furthermore, we derive new sharp lower bounds on ck(G) for regular graphs of degree ranging from k+1 to 2k−1 and for graphs of maximum degree k+1, and we determine exact values of ck(G) for certain classes of trees.
We show that every (k + 1)-regular graph has a minimum k-conversion set that avoids certain structures in its induced subgraph. These results lead to new proofs of several known results on colourings and forest partitions of (k + 1)-regular graphs and graphs of maximum degree k + 1.
Title: The A4-structure for a Graph
Speaker: Fay Ye, University of Victoria
Date and time:
29 Mar 2018,
10:00am -
11:00am
Location: HSD A264
Event type: Discrete math seminar
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Title: Elliptic operators and K-Homology" (part 1 of 2)
Speaker: Anna Duwenig, University of Victoria
Date and time:
28 Mar 2018,
3:30pm -
4:45pm
Location: CLE D 132
Event type: Operator theory seminar
Read full description
Abstract: Any symmetric, elliptic differential operator on a smooth
manifold gives rise to a K-Homology class for said manifold. In these
talks, we will first provide the necessary background to understand this
Theorem by introducing Kasparov's K-Homology and the notion of
differential operators. We will then sketch a proof for the case of
compact manifolds.
Title: Modeling, analysis and control of biological systems
Speaker: Ismail Belgacem, University of Victoria
Date and time:
28 Mar 2018,
3:30pm -
4:20pm
Location: DSB C130
Event type: Applied math seminar
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Abstract: These systems can be: continuous or discrete, depending on the modeling approach: ODE or piecewise affine systems (hybrid: PWA). Generally they are also nonlinear, of large dimensions, with different time-scales and complex to analyze. First, we present the modeling of metabolic reactions (biochemical or enzymatic), e.g. Michaelis-Menten. Then we present the classical model of gene expression which only involves concentrations of mRNAs and of proteins and compared to a detailed model of genetic machinery within the cell involving the main actors of the transcription-translation process, such as RNA polymerase and ribosomes. We study the reduction and stability analysis of a transcription-translation model of RNA polymerase where we have a closed loop from the produced RNA polymerase (end-product) to the transcription step (RNA polymerase is needed to transcribe its own gene). Using model parameters given by biologists, we separate the full system into fast and slow subsystems and we reduce the full system using singular perturbations (Tikhonov Theorem). The reduced system consists of ordinary differential and algebraic equations. We perform a dynamical study of this system using theory of monotone and compartmental systems or monotone and concave systems. We present also the control of small genetic networks systems for example qualitative control for PWA systems or sliding mode control for negative (inhibition) feedback loops (ODE).
Title: Mallow Permutations, Stable Matchings and Scaling Limits
Speaker: Omer Angel, University of British Columbia
Date and time:
26 Mar 2018,
3:30pm -
4:20pm
Location: MacLaurin Building, room D110
Event type: PIMS lectures
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We present a new representation of the Mallows permutations to stable matchings on a random bi-partite graph. We also derive new results for the scaling limits of the cycles in the Mallows permutations in terms of the Ethier-Kurtz diffusion.
Joint with Ander Holroyd, Tom Hutchcroft and Avi Levy.
(pre-lecture refreshments @2:45pm in DTB A514)
Download poster (PDF)
Title: 28th Coast Combinatorics Conference
Date:
24 Mar
to
25 Mar 2018
Location: David Turpin Building Room A102
Event type: Conferences and workshops
Read full description
The Coast Combinatorics Conferences are low-key meetings that welcome 30-minute (or so) talks on any topic in discrete mathematics and/or theoretical computer science. They are informal and largely "self-serve", meaning that there is no registration fee, no main speaker, and you may be on your own for coffee etc. at a nearby cafe. Sometimes you may even need to introduce yourself when it is your time to speak.
Everyone is welcome to attend the CCC. Please let us know if you are coming by sending email to Gary MacGillivray: gmacgill at UVic dot ca. It makes planning easier.
We are in the process of arranging a lunch booking for Saturday, a social event (happy hour) for Saturday evening. Details are not available yet.
Confirmed Speakers (so far)
Andrei Bulatov (Simon Fraser)
Patrick Fowler (University of Sheffield)
Leslie Hogben (Iowa State University and American Institute of Mathematics)
Sean McGuinness (Thompson Rivers)
Bojan Mohar (Simon Fraser)
Richard Nowakowski (Dalhousie)
Farzaneh Piri (Semnan University)
Hal Sudborough (University of Texas at Dallas)
Boting Yang (Regina)
For more information see the conference website.
Title: The Inverse Eigenvalue Problem of a Graph
Speaker: Leslie Hogben, Iowa State University and American Institute of Mathematics
Date and time:
22 Mar 2018,
3:30pm -
4:20pm
Location: HSD A264
Event type: PIMS lectures
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Inverse eigenvalue problems appear in various contexts throughout mathematics and engineering, and refer to determining whether or not there is a matrix with a prescribed structure (e.g., tridiagonal) and prescribed spectral property (e.g., having a given nullity, or having few distinct eigenvalues). For a given graph G, the associated matrices are real, symmetric, and have off-diagonal nonzero entries exactly where G has edges. The inverse eigenvalue problem of G (abbreviated by IEPG) is to determine the collection of all possible spectra (multisets of eigenvalues) for such matrices. Inverse eigenvalue problems and the background of this problem will be described, together with techniques such as the fundamental work of Colin de Verdière and the Strong Arnold Property. Two recent extensions of the Strong Arnold Property that target a better understanding of all possible spectra and their associated multiplicities will be presented; these are referred to as the Strong Spectral Property and the Strong Multiplicity Property. Applications of these properties to the inverse eigenvalue problem of a graph will be discussed, including the solution of IEPG for all graphs of order at most five.
Download poster (PDF)
Title: A local Formula for the Dolbeault Operator on the Sphere
Speaker: Dan Hudson, University of Victoria
Date and time:
21 Mar 2018,
3:30pm -
4:45pm
Location: CLE D 132
Event type: Operator theory seminar
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ABSTRACT: The Dolbeault operator is a differential operator canonically associated to a complex manifold. In this talk we will develop the background on complex manifolds needed to give the definition of the Dolbeault operator, talk briefly about the Hodge star operator, and find a formula for the adjoint of the Dolbeault operator. We will then restrict our attention to the sphere S2 to derive a local formula for the Dolbeault operator and its adjoint. Finally, we will compute the index of the Dolbeault operator. If time permits, we will conclude by mentioning some instances where this operator makes an appearance.
Title: Conservative methods for dynamical systems
Speaker: Andy Wan, McGill University
Date and time:
21 Mar 2018,
3:30pm -
4:20pm
Location: DSB C130
Event type: Applied math seminar
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We present a new class of conservative method, called the multiplier method, which enables systematic construction of conservative schemes for general dynamical systems. Specifically, the multiplier method can preserve arbitrary forms of conserved quantities and is applicable to systems without a symplectic or variational structure, such as dissipative systems. We illustrate this method on a variety of dynamical systems and discuss a connection between conservative methods and long-term stability.
This is joint work with Alexander Bihlo at Memorial University of Newfoundland and Jean-Christophe Nave at McGill University.
Title: Imaginary Geometry
Speaker: Gourab Ray, University of Victoria
Date and time:
19 Mar 2018,
3:30pm -
4:20pm
Location: DSB C126
Event type: Dynamics seminar
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Abstract: I will give an informal overview of the an interconnection
between the Gaussian free field and SLE (Schramm Loewner Evolution) curves
which is given the name "imaginary geometry" by its creators Miller and
Sheffield. No previous knowledge of either Gaussian free field or SLE will
be assumed.
Title: Quantifier Elimination in C*-algebras
Speaker: Todd Schmid, University of Victoria
Date and time:
15 Mar 2018,
10:00am -
11:20am
Location: Mac D010
Event type: Operator theory seminar
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Abstract: Generally speaking, model theory seeks to measure the
complexity of the formulas of modern mathematics.
The study was initially restricted to discrete structures, but
contributions from Chang and Kiesler in the 1960s, and in the past two
decades from Ben Yaacov, Berenstein, and many others, led to a
continuous logic suitable for metric structures.
During this talk, we will discuss applications of continuous logic to
C*-algebras, how one measures the complexity of formulas from the theory
of C*-algebras, and an explicit measurement of this complexity in the
finite-dimensional case.
Title: An introduction to graphons (from a layman)
Speaker: Peter Dukes, University of Victoria
Date and time:
15 Mar 2018,
10:00am -
11:00am
Location: HSD A264
Event type: Discrete math seminar
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Title: Equilibrium, social welfare and optimal structure in hierarchical Public goods games
Speaker: Yifen Mu, University of Victoria
Date and time:
14 Mar 2018,
3:30pm -
4:20pm
Location: DSB C130
Event type: Applied math seminar
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Abstract: Game theory is a powerful tool to formulate the conflict and cooperation between self-interested people and to predict individual or social human behavior. Therein hierarchical games study the games with possibly general hierarchical structures between players, which can naturally arise from the non-symmetry in time or space of players and thus exist widely in many kinds of scenarios. The equilibrium becomes Stackelberg-Nash equilibrium in such games. In this talk we will investigate two specific hierarchical games, i.e., the discrete and continuous Public goods games with discrete and continuous actions respectively. Public goods game models the profound phenomenon of “Tragedy of the Commons” and is a standard model in experimental economics. We will give the explicit solution of the Stackelberg-Nash equilibrium of the games by solving optimization problems. The equilibrium results show counterintuitive phenomena in hierarchical games and reveal the significant influence of hierarchical structure to the system. Then based on the solution of equilibrium, we will consider the inverse problem and obtain the optimal hierarchical structure which can reach the best optimal social welfare.
Title: A tight excess risk bound via a new complexity based on a unification of PAC-Bayesian, normalized maximum likelihood, and Radema
Speaker: Nishant Mehta, University of Victoria, Computer Science
Date and time:
13 Mar 2018,
2:30pm -
3:20pm
Location: DSB C108
Event type: Statistics seminar
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I will talk about a new notion of complexity, COMP, that interpolates between (and generalizes) some existing complexity notions from statistical learning theory. I will first derive COMP as a generalization of the Shtarkov sum, the normalizer in the normalized maximum likelihood (NML) distribution. When the NML distribution exists, the logarithm of the Shtarkov sum is precisely equal to the minimax regret for individual sequence prediction under log loss. Next, via a PAC-Bayesian analysis, I will show how COMP can be used to obtain tight upper bounds on the excess risk for randomized estimators (which include generalized Bayesian estimators). This excess risk bound will be in terms of COMP itself. Under a certain specialization, further upper bounding COMP leads to a standard PAC-Bayesian excess risk bound whose right hand side is the information complexity (essentially the empirical excess risk plus an additional complexity term involving the KL divergence from the posterior distribution to the prior distribution). Under a different specialization, the special case of empirical risk minimization with VC-type classes and large classes whose empirical L2 entropy exhibits polynomial growth, we will see how COMP is upper bounded in a way which yields optimal rates of convergence of the excess risk for such classes. Along the way, we will see connections to Rademacher complexity, and, in particular, we will recover bounds based on local Rademacher complexity while completely avoiding complicated local Rademacher complexity-based arguments. This is joint work with Peter Grünwald at CWI (in Amsterdam) and Leiden University.
Title: Stability results for non-autonomous dynamical systems
Speaker: Cecilia Gonzalez Tokman, University of Queensland
Date and time:
12 Mar 2018,
3:30pm -
4:20pm
Location: DSB C126
Event type: Dynamics seminar
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Abstract: In this talk we discuss recent developments concerning stability
properties of non-autonomous dynamical systems, motivated by the ergodic
theoretical study of random, forced or time-dependent systems and their
coherent structures. In the setting of random interval maps we present
results about stability of random absolutely continuous invariant
measures. In the context of multiplicative ergodic theory, we discuss
results on stability of Lyapunov exponents and Oseledets spaces in finite
and infinite-dimensional settings. This is based on joint works with Gary
Froyland, Rua Murray and Anthony Quas.
Title: Doubly Lexical Orderings of Matrices
Speaker: Jing Huang, University of Victoria
Date and time:
08 Mar 2018,
10:00am -
11:00am
Location: HSD A264
Event type: Discrete math seminar
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Title: Bratteli diagrams and flat surfaces (Part 2 of 2)
Speaker: Ian Putnam, University of Victoria
Date and time:
07 Mar 2018,
3:30pm -
4:45pm
Location: CLE D 132
Event type: Operator theory seminar
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Abstract: Flat surfaces (also translation surfaces) are specific types
of dynamical systems which have received a great deal of attention, I
will give an outline of their construction in the finite genus case.
Bratteli diagrams are combinatorial objects, initially introduced to
describe approximately finite-dimensional (AF) C*-algebras and have also
been used for models of actions on Cantor sets. I will describe recent
work of Kathryn Lindsey and Rodrigo Trevino to construct examples of
flat surfaces in the infinite genus case from a Bratteli diagram. The
first talk will be entirely dynamical (and will likely have more
constructions than theorems). The second will focus on the rather
mysterious relationship between the AF-algebras and the C*-algebras
associated with the flat surface dynamics. (Joint work, in progress,
with Rodrigo Trevino.)
Title: Host Contact Structure is Important for the Recurrence of Influenza A
Speaker: Juan Jaramillo, UVic Computer Science
Date:
07 Mar 2018
Location: DSB C130
Event type: Applied math seminar
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Abstract: An important characteristic of influenza A is its ability to escape host immunity through antigenic drift. A novel influenza A strain that causes a pandemic confers full immunity to infected individuals, yet because of antigenic drift, these individuals have decreased immunity to drifted strains. We compute the required decrease in immunity so that a recurrence is possible. Models for influenza A must make assumptions on the contact structure on which the disease spreads. By determining the local stability of the disease free equilibrium via the reproduction number, we show that the classical random mixing assumption predicts an unrealistically large decrease of immunity before a recurrence is possible. We improve over the classical random mixing assumption by incorporating a contact network structure. A complication of contact networks is correlations induced by the initial pandemic. Thus in this presentation, I share joint work with P. van den Driessche and Junling Ma where we provide a novel analytic derivation of such correlations and show that contact networks may require a dramatically smaller drop in immunity before recurrence. Hence, the key new insight in our work is that on contact networks the establishment of a new strain is possible for much higher immunity levels of previously infected individuals than predicted by the commonly used random mixing assumption. This suggests that stable contacts like classmates, coworkers and family members are a crucial path for the spread of influenza in human population.
Title: Projections of a random walk on a space of binary trees
Speaker: Noah Forman, University of Washington
Date and time:
05 Mar 2018,
3:30pm -
4:20pm
Location: DSB C126
Event type: Dynamics seminar
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Abstract: Consider the Markov process in the space of binary trees in
which, at each step, you delete a random leaf and then grow a new leaf in
a random location on the tree. In 2000, Aldous conjectured that it should
have a continuum analogue, which would be a continuum random tree-valued
diffusion. We will discuss a family of projectively consistent Markov
chains that are projections of this tree, and discuss how these
representations can be passed to the continuum. This is joint work with
Soumik Pal, Douglas Rizzolo, and Matthias Winkel.
Title: Minimum Chi-square Method for Estimating Population Size with Application to Capture-Recapture White Stork Data
Speaker: Sophia Zheng, University of Victoria
Date and time:
02 Mar 2018,
3:30pm -
4:30pm
Location: Clearihue Building B017
Event type: Graduate dissertations
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The Final Oral Examination for the Degree of
Master of Science (Department of Mathematics & Statistics)
Sophia (Yuyan) ZHENG
B.Sc., University of Victoria, 2016
“Minimum Chi-square Method for Estimating Population Size with Application to Capture-Recapture White Stork Data”
March 2, 2018 3:30pm Clearihue Building B017
Supervisory Committee:
Dr. Laura Cowen, Department of Mathematics & Statistics, UVic (Co-supervisor)
Dr. Min Tsao, Department of Mathematics & Statistics, UVic (Co-supervisor)
Chair of Oral Examination:
Dr.Xuekui Zhang, Department of Mathematics & Statistics, UVic
Title: Generalized Opposition Graphs
Speaker: Fay Ye, University of Victoria
Date and time:
01 Mar 2018,
10:00am -
11:20am
Location: HSD A264
Event type: Discrete math seminar
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Title: Bratteli diagrams and flat surfaces (Part 1 of 2)
Speaker: Ian Putnam, University of Victoria
Date and time:
28 Feb 2018,
3:30pm -
4:45pm
Location: CLE D 132
Event type: Operator theory seminar
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Abstract: Flat surfaces (also translation surfaces) are specific types
of dynamical systems which have received a great deal of attention, I
will give an outline of their construction in the finite genus case.
Bratteli diagrams are combinatorial objects, initially introduced to
describe approximately finite-dimensional (AF) C*-algebras and have also
been used for models of actions on Cantor sets. I will describe recent
work of Kathryn Lindsey and Rodrigo Trevino to construct examples of
flat surfaces in the infinite genus case from a Bratteli diagram. The
first talk will be entirely dynamical (and will likely have more
constructions than theorems). The second will focus on the rather
mysterious relationship between the AF-algebras and the C*-algebras
associated with the flat surface dynamics. (Joint work, in progress,
with Rodrigo Trevino.)
Title: Machine Learning Challenges in Music Technology
Speaker: George Tzanetakis, UVIc Computer Science
Date and time:
27 Feb 2018,
2:30pm -
3:20pm
Location: DSB C108
Event type: Statistics seminar
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The computer analysis of music is particularly challenging because of the multi-faceted and hierarchical nature of musical information. During the last 13 years techniques from machine learning have been leveraged in the field of music information retrieval to solve problems such as automatic genre classification, mood prediction and music recommendation. In most of these cases standard techniques from machine learning such as supervised classification and unsupervised clustering were utilized.
In this talk I will talk about two music analysis problems for which more advanced machine learning approaches are required. The first problem is automatic tag annotation and I will describe stacking which is an layered classifier architecture for solving this problem. The second problem is the hierarchical analysis of music into segments, chords and keys and I will describe the use of Markov Logic Networks to solve this problem. Markov Logic Networks are a rich formalism that combines the expressiveness of first-order logic for representing relations with the statistical learning abilities of data mining. The third problem I am going to discuss is the use of a machine learning approach to enable expressive bowing control of a virtual physical violin model, work that connect sound synthesis with music information retrieval.
Title: Ergodic Optimization: An overview
Speaker: Anthony Quas, University of Victoria
Date and time:
26 Feb 2018,
3:30pm -
4:20pm
Location: DSB C126
Event type: Dynamics seminar
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Abstract: As a prelude to a reading group being organized by David Goluskin, I will introduce the subject of ergodic optimization, and talk about the questions, the paradigms, and some results in the field.
Title: Traveling waves of bacteria at the mesoscopic scale
Speaker: Vincent Calvez, ENS, Lyon-France
Date and time:
22 Feb 2018,
3:30pm -
4:20pm
Location: DSB C124
Event type: Applied math seminar
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Abstract: Concentration waves of swimming bacteria Escherichia coli were described
in his seminal paper by Adler (Science 1966). These experiments gave
rise to intensive PDE modelling and analysis, after the original model
by Keller and Segel (J. Theor. Biol. 1971), and the work of Alt (J.
Math. Biol. 1980) and his co-authors. Together with Bournaveas,
Perthame, Raoul and Schmeiser, we have revisited this old problem from
the point of view of kinetic transport equations. This framework is very
much adapted to the so-called run-and-tumble motion, in which bacteria
modulate the frequency of reorientation (tumble) -- and thus the
duration of free runs -- depending on chemical variations in the
environment. I will present some recent analytical and numerical results
about the existence of traveling wave solutions for a coupled
kinetic-parabolic system describing concentration waves of bacteria in a
micro-channel. The parabolic-parabolic problem obtained in the diffusive
limit admits unique traveling wave solutions without any restriction on
the parameters. This is in opposition to the kinetic-parabolic system
for which solutions may be not unique, or may not exist for some extreme
range of parameters.
Title: Expansive dynamical systems and C*-algebras
Speaker: Robin Deeley, Colorado University, Boulder
Date and time:
08 Feb 2018,
10:00am -
11:20am
Location: MAC D010
Event type: Operator theory seminar
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Abstract: I will introduced expansive dynamical systems starting with
the definition. Smale spaces and subshifts are particular examples of
these systems. Ruelle, Putnam and Spielberg have constructed and studied
three groupoid C*-algebras associated to a Smale space. I will discuss
my recent work (with a number of co-authors) on the structure of these
C*-algebras. In addition, using work of Thomsen, a generalization of
these C*-algebraic constructions from Smale spaces to expansive
dynamical systems will be considered. This last topic is work in progress.
Title: A characterization theorem for the Gaussian free field: Part II
Speaker: Gourab Ray, University of Victoria
Date and time:
05 Feb 2018,
3:30pm -
4:20pm
Location: DSB C126
Event type: Dynamics seminar
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Abstract: The Gaussian free field is a natural two dimensional analogue of
Brownian motion which arise as a universal scaling limit of many natural 2
dimensional models. We characterize this object using an axiomatic
approach. We prove that any random distribution satisfying conformal
invariance and a form of domain Markov property and having a finite moment
condition must be the Gaussian free field. We also present some open
problems regarding what happens beyond the Gaussian free field. Joint work
with Nathanael Berestycki and Ellen Powell.
Title: Paths, stars and the number 3
Speaker: Frank Yang, University of Victoria
Date and time:
01 Feb 2018,
10:00am -
11:00am
Location: HSD A264
Event type: Discrete math seminar
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Frank will talk about Bruce Reed's paper, "Paths, stars and the number 3".
Title: Arens Regularity
Speaker: Mitch Haslehurst, University of Victoria
Date and time:
31 Jan 2018,
3:30pm -
4:45pm
Location: CLE D132
Event type: Operator theory seminar
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Abstract: Around 1950, Richard Arens discovered two ways of defining a
multiplication operation on the double dual space of a Banach algebra
which is submultiplicative and extends the multiplication on the
original algebra. In this talk I will discuss necessary and sufficient
conditions for these two definitions to coincide, as well as present
some examples.
Title: Shock formation for Prandtl's equations and Burgers equation with transversal
Speaker: Charles Collot, NYU
Date and time:
31 Jan 2018,
3:30pm -
4:20pm
Location: DSB C130
Event type: Applied math seminar
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This talk is about finite time singularity formation for solutions to Prandtl's boundary layer equations and a simplified version that is Burgers equation with transversal viscosity which arise in fluid dynamics. Prandtl's equations arise as a limit model of Navier-Stokes equations for the description of a fluid near the boundary of its domain in the inviscid limit. Even if the initial datum is smooth and well localised, the maximal time of existence for the corresponding solution of both equations can be finite. In that case, the gradient of the solution becomes unbounded in finite time, meaning that the local properties of the fluid will have some discontinuity. One important issue is to understand this phenomenon: when and how it happens. We will first focus on the available results for Prandtl's equations, which will lead us to examine Burgers equation. The core of the presentation will be the precise construction of solutions to Burgers equation forming a shock in finite time. This is joint work with T.E. Ghoul, S. Ibrahim and N. Masmoudi.
Title: Math Mania
Date and time:
30 Jan 2018,
6:30pm -
8:00pm
Location: Eagle View Elementary, 97 Talcott Rd.
Event type: Education and outreach
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This Alternative Math Education event will present fun methods of teaching math and computer science concepts to children (and adults!) using games and art.
Lots of hands-on activities!
Including:
• A Sorting Network
• An Impossible Balancing Act
• Bubbles
• Mathematical Puzzles
• The Guessing Game
• Sudoku• The Penny Game• The Set Game• And many more!
Organizers:
Brigitte Sandhu
For more information please contact the school or Brigitte Sandhu, PIMS University of Victoria Site at:
T: 250-472-4271
E: pims@uvic.ca
Title: Ensembles of Regularized Linear Models
Speaker: Ezequiel Smucler, University of Buenos Aires
Date and time:
30 Jan 2018,
2:30pm -
3:20pm
Location: DSB C108
Event type: Statistics seminar
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Abstract: We propose an approach for building ensembles of regularized linear models by optimizing a novel objective function, that encourages sparsity within each model and diversity among them. Our procedure works on top of a given penalized linear regression estimator (e.g., Lasso, Elastic Net, SCAD) by fitting it to possibly overlapping subsets of features, while at the same time encouraging diversity among the subsets, to reduce the correlation between the predictions that result from each fitted model. The predictions from the models are then aggregated. For the case of an Elastic Net penalty and orthogonal predictors, we give a closed form solution for the regression coefficients in each of the ensembled models. An extensive simulation study and real-data applications show that the proposed method systematically improves the prediction accuracy of the base linear estimators being ensembled. Extensions to GLMs and other models are discussed.
Joint work with Anthony Christidis, Laks Lakshmanan and Ruben Zamar.
Title: A characterization theorem for the Gaussian free field
Speaker: Gourab Ray, University of Victoria
Date and time:
29 Jan 2018,
3:30pm -
4:20pm
Location: DSB C126
Event type: Dynamics seminar
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Abstract: The Gaussian free field is a natural two dimensional analogue of
Brownian motion which arise as a universal scaling limit of many natural 2
dimensional models. We characterize this object using an axiomatic
approach. We prove that any random distribution satisfying conformal
invariance and a form of domain Markov property and having a finite moment
condition must be the Gaussian free field. We also present some open
problems regarding what happens beyond the Gaussian free field. Joint work
with Nathanael Berestycki and Ellen Powell.
Title: Coalition and Opposition Graphs
Speaker: Fay Ye, University of Victoria
Date and time:
25 Jan 2018,
10:00am -
11:00am
Location: HSD A264
Event type: Discrete math seminar
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Title: KMS states on groupoid C*-algebras (part 3 of 3)
Speaker: Chris Bruce, University of Victoria
Date and time:
24 Jan 2018,
3:30pm -
4:45pm
Location: CLE D132
Event type: Operator theory seminar
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Abstract: In these expository talks, we will discuss the problem of
classifying KMS states on the C*-algebras of étale groupoids. Our
primary focus is a theorem of Neshveyev: in the case that the time
evolution is defined by a real-valued 1-cocycle, it gives a description
of the KMS states in terms of measurable fields of traces on the
C*-algebras of the isotropy groups. We also discuss some applications.
Title: Ground State Solutions of the Gross Pitaevskii Equation Associated to Exciton-Polariton Bose-Einstein Condensates
Speaker: Slim Ibrahim, University of Victoria
Date and time:
24 Jan 2018,
3:30pm -
4:20pm
Location: DSB C130
Event type: Applied math seminar
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We investigate the existence of ground state solutions of a Gross-Pitaevskii equation modeling the dynamics of pumped Bose Einstein condensates (BEC). The main interest in such BEC comes from its important nature as macroscopic quantum system, constituting an excellent alternative to the classical condensates which are hard to realize because of the very low temperature required. Nevertheless, the Gross Pitaevskii equation governing the new condensates presents some mathematical challenges due to the presence of the pumping and damping terms. Following a self-contained approach, we prove the existence of ground state solutions of this equation under suitable assumptions: This is equivalent to say that condensation occurs in these situations. We also solve the Cauchy problem of the Nonlinear Schrodinger equation and prove some corresponding laws.
Title: Evidence from the Shanghai-Hong Kong Stock Connect Program
Speaker: Xuekui Zhang, University of Victoria
Date and time:
23 Jan 2018,
2:30pm -
3:20pm
Location: DSB C108
Event type: Statistics seminar
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The Shanghai-Hong Kong Stock Connect Program is a cross-boundary investment channel that connects the Shanghai Stock Exchange and the Hong Kong Stock Exchange. This program was launched on 17 November 2014, and subsequently investors in each market were able to trade shares on the other market locally. To understand how this policy affected the stock market, we collected per-second trade information for 564 connected stocks and 454 unconnected stocks from October 1 2014 to December 31 2014. This dataset contains ~1000 stocks multiplied by ~millions (number of seconds in each month) records. Each record contains information such as the top 10 buying/selling price and volume. From this big dataset, we want to learn if the trading cost was lowered by the new policy and if the trading cost has become more stable (e.g., smaller variance) after the new policy. We also want to find the time of pattern change and its relation to the policy launch time. I’d like to use this project to share with students about how I was able to migrate tools/tricks from healthcare/genomics research to financial research.
Title: Local Area Random Graphs
Speaker: Anthony Quas, University of Victoria
Date and time:
22 Jan 2018,
3:30pm -
4:20pm
Location: DSB C126
Event type: Dynamics seminar
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Ackermann, Erdős, Rényi and Rado studied the random graphs obtained on the
natural numbers where each pair of vertices is independently joined with
probability p (0<p<1). Counter-intuitively, there is a single random
graph, R, such that for any p in (0,1), almost surely the graph obtained
above is isomorphic to R. We study a variant of this model in which the
vertices are a countable set of points of a separable metric space, X, and
x_i and x_j are joined with probability p if d(x_i,x_j)<1 (while if
d(x_i,x_j)>=1, there is no edge joining x_i and x_j). We call this a local
area random graph. In this talk, I will address the case where X is the
Banach space C[0,1] and the countable set of points is obtained by
sampling a countable collection of points from a measure on C[0,1].
(joint work with Anthony Bonato and Jeannette Janssen)
Title: Frugal Homomorphisms
Speaker: Stefan Bard, University of Victoria
Date and time:
18 Jan 2018,
10:00am -
11:00am
Location: HSD A264
Event type: Discrete math seminar
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Stefan will talk about his recent results in frugal homomorphisms.
Title: KMS states on groupoid C*-algebras (part 2 of 3)
Speaker: Chris Bruce, University of Victoria
Date and time:
17 Jan 2018,
3:30pm -
4:45pm
Location: CLE D132
Event type: Operator theory seminar
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Abstract: In these expository talks, we will discuss the problem of
classifying KMS states on the C*-algebras of étale groupoids. Our
primary focus is a theorem of Neshveyev: in the case that the time
evolution is defined by a real-valued 1-cocycle, it gives a description
of the KMS states in terms of measurable fields of traces on the
C*-algebras of the isotropy groups. We also discuss some applications.
Title: Linear stability and instability of periodic orbits by Conley-Zehnder index
Speaker: Yanxia Deng, University of Victoria
Date and time:
17 Jan 2018,
2:30pm -
3:20pm
Location: DSB C124
Event type: Applied math seminar
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Abstract: The determination of stability type for periodic orbits in Hamiltonian systems is the first important goal of dynamics, after the question of existence. For linearized stability, the main tool in this quest is the theory of Lyapunov multipliers and the consequent structure of the monodromy matrix for a periodic orbit. In this talk I will present a criterion for the linear instability of certain periodic orbits using the Morse index and the Conley-Zehnder index theory. One consequence of our result is that an oriented isolated minimizing closed geodesic in an even dimensional Riemannian manifold is always unstable. For one degree of freedom time-dependent Hamiltonian systems, I will give an alternative and equivalent formulation of linearized stability in terms of the Conley-Zehnder index. Applications include stable harmonic oscillations for forced pendulum type equations and some examples of Hamiltonian systems of kinetic plus potential type.
Title: KMS states on groupoid C*-algebras (part 1 of 2)
Speaker: Chris Bruce, University of Victoria
Date and time:
10 Jan 2018,
3:30pm -
4:45pm
Location: CLE D132
Event type: Operator theory seminar
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Abstract: In these expository talks, we will discuss the problem of
classifying KMS states on the C*-algebras of étale groupoids. Our
primary focus is a theorem of Neshveyev: in the case that the time
evolution is defined by a real-valued 1-cocycle, it gives a description
of the KMS states in terms of measurable fields of traces on the
C*-algebras of the isotropy groups. We also discuss some applications.
Title: Zeno breaking, the Contact effect and sensitive behaviour in piecewise-linear systems
Speaker: Rod Edwards, University of Victoria
Date and time:
10 Jan 2018,
2:30pm -
3:20pm
Location: DSB C124
Event type: Applied math seminar
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Abstract:
Non-smooth approximation to steep sigmoidal switching networks has proven to be a fruitful approach to analysis of their behaviour, for example in the study of dynamics of gene regulation. However, the introduction of discontinuities also leads to some analytic challenges, and in situations where the true system is believed to be smooth, it is especially important to be sure that the behaviour predicted by the non-smooth analysis is close to that of nearby smooth systems, and to interpret results accordingly. Here we use particular examples to highlight several challenges of this type, in which care needs to be taken in conducting or interpreting the non-smooth analysis. Autoregulation in piecewise linear models of gene networks leads to sliding motion in threshold hyperplanes or their intersections, and trajectories in which two (or more) variables spiral in to threshold intersections in finite time. In the latter case, an infinite number of threshold transitions occur during the finite time convergence to the intersection, as in Zeno's ``paradox''. After convergence, other variables continue to evolve (hence ``Zeno breaking''), and many possibilities arise, including non-uniqueness. Exotic forms of behavior through threshold regions (boundary layers) in the piecewise linear systems lead to interesting and sensitive behavior in nearby steep sigmoidal systems. Also, autoregulation in gene networks is actually accomplished by a sequence of steps, and introducing intermediate variables leads to more general piecewise linear systems with other kinds of non-uniqueness, such as what I call the "Contact" effect.
Title: The Poincaré Conjecture and Milnor's Exotic Spheres
Speaker: Angela Wu, London School of Number Theory and Geometry
Date and time:
05 Jan 2018,
3:00pm -
5:00pm
Location: Clearihue C112
Event type: Education and outreach
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All students in Math and Statistics at UVic (this includes anybody in a math or stats course) are invited to this event.
Title: The Poincaré Conjecture and Milnor's Exotic Spheres
Speaker: Angela Wu, PhD student, London School of Number Theory and Geometry
Location: Clearihue C112
Coffee, tea, doughnuts, sushi 3:00pm-4:00pm
Talk at 4:00pm-5:00pm
Abstract: Henri Poincaré (polymath, mine engineer, set theory skeptic) conjectured that every simply connected, closed, 3-dimensional manifold is homeomorphic to the 3-sphere. It took mathematicians nearly a century to prove this theorem but many fewer years to come up with variations. What if we consider manifolds of dimension n? What if we consider more geometric structure?
In this talk, we will learn some general differential geometry, look at the smooth Poincaré conjecture: Every n-dimensional manifold homeomorphic to the n-sphere is diffeomorphic the n-sphere, and follow Milnor's discovery of exotic spheres in seven dimensions. No prerequisites will be assumed so don't be alarmed if you don't know all the words in these last two paragraphs.
There will be a bit of history, a couple of ball jokes, and some really cool math.
Title: Is Ocean Reflectance Acquired by Ferry Passengers Robust for Science Applications?
Speaker: Yuyan Yang, University of Victoria
Date and time:
12 Dec 2017,
10:00am -
11:00am
Location: CLE B007
Event type: Graduate dissertations
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Notice of the Final Oral Examination for the Degree of Master of Science
of
YUYAN YANG
BSc (South China Agricultural University, 2015)
“Is Ocean Reflectance Acquired by Ferry Passengers Robust for Science Applications?”
Department of Mathematics and Statistics
Tuesday, December 12, 2017 10:00 A.M. Clearihue Building Room B007
Supervisory Committee:
Dr. Laura Cowen, Department of Mathematics and Statistics, University of Victoria (Supervisor) Dr. Maycira Costa, Department of Geography, UVic (Outside Member)
External Examiner:
Dr. Yvonne Coady, Department of Computer Science, UVic
Chair of Oral Examination:
Dr. Dale Ganley, School of Business, UVic
Abstract
Monitoring the dynamics of the productivity of ocean water and how it affects fisheries is essential for management. It requires data on proper spatial/temporal scales, which can be provided by operational ocean colour satellites. However, accurate productivity data from ocean colour imagery is only possible with proper validation of, for instance, the atmospheric correction applied to the images. In situ water reflectance data is of great value due to the requirements for validation and it is traditionally measured with the Surface Acquisition System (SAS) solar tracker system. Recently, an application, `HydroColor', was developed for mobile devices to acquire water reflectance data. We examine the accuracy of the water reflectance acquired by HydroColor with the help of trained and untrained citizens under different environmental conditions. We used water reflectance data acquired by SAS solar tracker and HydroColor onboard the BC ferry Queen of Oak Bay from July to September 2016. Monte Carlo permutation F-tests were used to assess whether the differences between measurements collected by SAS solar tracker and HydroColor with citizens were significant. Results showed that citizen HydroColor measurements were accurate in red, green, and blue bands, as well as red/green and red/blue ratios under different environmental conditions. Piecewise models were developed for correcting HydroColor blue/green water reflectance ratios based on the SAS solar tracker measurements. In addition, we found that a trained citizen obtained higher quality HydroColor data under clear skies at noon.
Title: CABS Seminar: The Analysis of Face Perception MEG and EEG Data Using a Potts-Mixture Spatiotemporal Joint Model
Speaker: Yin Song, University of Victoria
Date and time:
08 Dec 2017,
3:00pm -
4:00pm
Location: Cornett A228
Event type: Statistics seminar
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Abstract: In this paper we analyze magnetoencephalography (MEG) and electroencephalography (EEG) data from a single subject with the objective of determining the location and dynamics of brain activity when this subject is repeatedly presented with stimuli corresponding to pictures of scrambled faces and required to make a symmetry judgement. To meet this objective we must consider the ill-posed inverse problem arising when MEG and EEG are used to measure electromagnetic brain activity over an array of sensors at the scalp and the goal is to map these data back to the sources of neural activity within the brain. A novel challenge arising with the current dataset is that the study involves combined MEG and EEG data, and it is of interest to combine these two different modalities together.
We propose a new Bayesian finite mixture state-space model that builds on previously developed models and incorporates two major extensions that are required for our application: (i) We combine EEG and MEG data together and formulate a joint model for dealing with the two modalities simultaneously; (ii) we incorporate the Potts model to represent the spatial dependence in an allocation process that partitions the cortical surface into a small number of latent states termed meso-states. We formulate the new spatiotemporal model and derive an efficient procedure for simultaneous point estimation and model selection based on the iterated conditional modes algorithm combined with local polynomial smoothing. The proposed method results in a novel estimator for the number of mixture components and is able to select active brain regions which correspond to active variables in a high-dimensional dynamic linear model. The methodology is investigated using synthetic data and then applied to our motivating application to examine the neural response to the perception of scrambled faces.
Title: A State-Space Formulation of the Jolly-Seber-Tag-Loss Model with Dependent Tags
Speaker: Yan Xu, University of Victoria
Date and time:
08 Dec 2017,
1:30pm -
2:30pm
Location: CLE C316
Event type: Graduate dissertations
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The Final Oral Examination for the Degree of
Master of Science (Department of Mathematics & Statistics)
Yan XU
2015 Nanjing University of Finance and Economics (B.A)
“A State-Space Formulation of the Jolly-Seber-Tag-Loss Model with Dependent Tags”
December 8th, 2017 1:30 pm
CLE C316 Supervisory Committee:
Dr. Laura Cowen, Department of Mathematics & Statistics, UVic (Supervisor)
Dr. Farouk Nathoo, Department of Mathematics & Statistics, UVic (Member)
Chair of Oral Examination:
Dr. Xuekui Zhang, Department of Mathematics & Statistics, UVic
Title: Host Contact Structure is Important for the Recurrence of Infulenza A
Speaker: Juan Jaramillo, University of Victoria
Date and time:
06 Dec 2017,
10:00am -
11:00am
Location: Clearihue Building Room B007
Event type: Graduate dissertations
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Notice of the Final Oral Examination for the Degree of Master of Science
of
JUAN M. JARAMILLO
BSc (University of Victoria, 2015)
“Host Contact Structure is Important for the Recurrence of Infulenza A”
Department of Mathematics and Statistics
Wednesday, December 6, 2017 10:00 A.M.
Clearihue Building
Room B007
Supervisory Committee:
Dr. Pauline van den Driessche, Department of Mathematics and Statistics, University of Victoria (Co-Supervisor)
Dr. Junling Ma, Department of Mathematics and Statistics, UVic (Co-Supervisor)
External Examiner:
Dr. Istvan Kiss, Department of Mathematics, University of Sussex
Chair of Oral Examination:
Dr. Bruce Ravelli, Department of Sociology, UVic
Abstract
An important characteristic of influenza A is its ability to escape host immunity through antigenic drift. A novel influenza A strain that causes a pandemic confers full immunity to infected individuals, yet because of antigenic drift, these individuals have decreased immunity to drifted strains. We compute the required decrease in immunity so that a recurrence is possible. Models for influenza A must make assumptions on the contact structure on which the disease spreads. By computing the reproduction number, we show that the classical random mixing assumption predicts an unrealistically large decrease of immunity before a recurrence is possible. We improve over the classical random mixing assumption by incorporating a contact network structure. A complication of contact networks is correlations induced by the initial pandemic. Thus, we provide a novel analytic derivation of such correlations and show that contact networks may require a dramatically smaller drop in immunity before recurrence. Hence, the key new insight is that on contact networks the establishment of a new strain is possible for much higher immunity levels of previously infected individuals than predicted by the commonly used random mixing assumption. This suggests that stable contacts like classmates, coworkers and family members are a crucial path for the spread of influenza in human population.
Title: Putnam Math Competition
Date and time:
02 Dec 2017,
8:00am -
4:00pm
Location: Harry Hickman Building 110
Event type: Education and outreach
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The Putnam Mathematics Competition is held annually on the first Saturday in December. This year's contest is on Saturday, December 2, 2017 between 8:00am-4:00pm in Harry Hickman Building 110. Lunch will be provided.
Registration is now closed but if you are still interested you may contact Dr. Dukes at dukes@uvic.ca in case a spot becomes available.
Title: Embedding Seifert fibered spaces in the 4-sphere
Speaker: Ahmad Issa, U.T. Austin
Date and time:
01 Dec 2017,
10:00am -
11:00am
Location: DSB C122
Event type: Topology seminar
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Which 3-manifolds smoothly embed in the 4-sphere? This seemingly simple question turns out to be surprisingly subtle and difficult. In this talk, we restrict to the case of Seifert fibered 3-manifolds over an arbitrary oriented base surface F. Such a space M, with non-zero generalised Euler invariant, is determined by (F; e; r_1, ..., r_k) where e > 0 is an integer and r_1,...,r_k > 1 are rationals (here we've oriented M to bound a positive definite plumbing). For e >= k/2, we determine precisely which M pass a powerful obstruction to embedding based on Donaldson's theorem, and then attempt to either embed M or apply further obstructions in those cases. For e > k/2, this gives a complete determination of which such M embed. This is joint work with Duncan McCoy.
Title: Fuzzy Configurations
Speaker: Kaoruko Iwasaki, University of Victoria
Date and time:
30 Nov 2017,
10:00am -
11:00am
Location: HSD A270
Event type: Discrete math seminar
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A presentation of the Math 498 project.
Title: Morita Equivalence between the irrational rotation algebra and the crossed product of the foliated 2-torus (part2 of 2)
Speaker: Anna Duwenig, University of Victoria
Date and time:
29 Nov 2017,
3:30pm -
4:50pm
Location: CLE D131
Event type: Operator theory seminar
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The two algebras in question can be realized as groupoid C*-algebras whose underlying groupoids are equivalent. Thus, their associated C*-algebras are Morita equivalent.
To see this, we will first recall the crossed product construction for the two algebras and then briefly see how to align this with the groupoid construction. I will define what it means for the two groupoids to be equivalent, to then show that they indeed are. Finally, there is a theorem which lets us construct the wanted imprimitivity bimodule out of the groupoid equivalence.
(Disclaimer: I am not an expert on topological groupoids, so expect some hand-waving.)
Title: Using a Simple Multi-Scale Asymptotic Model to Study Scale Interactions of Tropical Convection
Speaker: Qiu Yang, Visitor at UVic
Date and time:
29 Nov 2017,
2:30pm -
3:20pm
Location: DSB C124
Event type: Applied math seminar
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In the past decades, the multi-scale asymptotic method is used as a well-developed technique to construct uniformly valid approximation solutions of perturbation problems. It is not until recently that the multi-scale asymptotic method is combined with numerical simulations for modeling scale interactions of tropical convection. The essential intuition behind is the fact that mathematically fast- and slow-scale variables are introduced in the multi-scale method to remove secular terms, while physically tropical convection also exhibits a hierarchy of organization across multiple spatiotemporal scales.
In this talk, I will first introduce a few observational evidence to show the multi-scale interactions of tropical convection. Particularly, we choose convectively coupled Kelvin waves as a research target to study here. Then I will review the related pioneering work by Majda (2007) and briefly go through the derivation of one simple multi-scale model as an example. Finally, I will show our recent results by using such a simple multi-scale model to study the upscale impact of mesoscale disturbances of tropical convection on convectively coupled Kelvin waves. Those who get interested can refer the following two papers for further details (
http://journals.ametsoc.org/doi/full/10.1175/JAS-D-17-0068.1) and (
http://journals.ametsoc.org/doi/abs/10.1175/JAS-D-17-0178.1).
Title: Linking mathematical models to public health policy: Use of Bayesian inference and Markov models in evaluating the current opioi
Speaker: Mike Irvine, (Institute for Applied Mathematics, UBC)
Date and time:
27 Nov 2017,
2:00pm -
3:00pm
Location: HSD A264
Event type: Statistics seminar
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ABSTRACT:
The rapid increase of fentanyl and fentanyl analogues in British Columbia has led to a public health emergency being declared and a rapid increase in overdoses and overdose-related deaths in the province. Numerous interventions have been proposed in response, however it is not clear how to evaluate these interventions where the rate of overdoses is rapidly changing. We introduce a Poisson Hidden Markov Model to incorporate knowledge on ambulance-attended overdoses, fentanyl-related deaths and illicit-drug related deaths. We explicitly model the use of Take Home Naloxone kits (THN), an opioid agonist used in reversing an overdose that has been widely distributed. The model was fit using a Bayesian framework with informative priors, taking into account expert knowledge and literature-based rate estimates. We use the fitted model to estimate the total number of deaths averted due to the use of THN and explore a number of counterfactual scenarios including if THN was distributed!
sooner and if the size of the at-risk population was reduced.
Title: A Perron-Frobenius Theorem for Cocycles of Matrices/Linear Operators, Part 3
Speaker: Joseph Horan, University of Victoria
Date and time:
23 Nov 2017,
2:30pm -
3:20pm
Location: Clearihue A211
Event type: Dynamics seminar
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Abstract: In this third of three talks (there will not be a fourth talk), we will see a brief example in the matrix case, to illustrate how the matrix cocycle P-F theorem can work in practice. We will then discuss why we want to extend the theorem to linear operators on infinite-dimensional Banach spaces, and some of the issues that arise when attempting to do so.
Title: Some remarks on domination
Speaker: Linda Neilson, University of Victoria
Date and time:
23 Nov 2017,
10:00am -
11:00am
Location: HSD A270
Event type: Discrete math seminar
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She’s going to talk about the results in the following paper:
Archdeacon, D.; Ellis-Monaghan, J.; Fisher, D.; Froncek, D.; Lam, P. C. B.; Seager, S.; Wei, B.; Yuster, R.
Some remarks on domination.
J. Graph Theory 46 (2004), no. 3, 207–210.
Title: Morita Equivalence between the irrational rotation algebra and the crossed product of the foliated 2-torus (possibly 1 of 2)
Speaker: Anna Duwenig, University of Victoria
Date and time:
22 Nov 2017,
3:30pm -
4:50pm
Location: CLE D131
Event type: Operator theory seminar
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The two algebras in question can be realized as groupoid C*-algebras whose underlying groupoids are equivalent. Thus, their associated C*-algebras are Morita equivalent. To see this, we will first recall the crossed product construction for the two algebras and then briefly see how to align this with the
groupoid construction. I will define what it means for the two groupoids to be equivalent, to then show that they indeed are. Finally, there is a theorem which lets us construct the wanted imprimitivity bimodule out of
the groupoid equivalence.
(Disclaimer: I am not an expert on topological groupoids, so expect some hand-waving.)
Title: The transient response to an equatorial heat source and its convergence to steady state: Implications for MJO theory
Speaker: Boualem Khouider, University of Victoria
Date and time:
22 Nov 2017,
2:30pm -
3:20pm
Location: DSB C124
Event type: Applied math seminar
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Abstract: The Matsuno-Gill model for the atmospheric steady-state response to an imposed equatorial heat source is perhaps the most successful set of reduced equations in the theory of tropical dynamics. While it was originally designed to explain some key features of the tropical climatology such as the Walker and Hadley circulations, it is increasingly used for other transient tropical disturbances such as the Madden-Julian oscillation (MJO).
Here, we provide a semi-analytic solution to the time dependent Matsuno-Gill equations, with periodic boundary conditions and without the long-wave approximation, based on a meridional expansion using the parabolic cylinder functions combined with the method of characteristics and Fourier series in the zonal direction. Our method of solution leads to an ODE system which is solved numerically. We use this transient solution to investigate the conditions under which the transient response convergences to the steady state and study the effect of a moving heat source on the structure of the response and speculate about its resemblance or not to the MJO structure. In particular, we look at the sensitivity of the long time behavior of the solution with respect to the model parameters, namely, the imposed dissipation rate and the speed of the moving heat source as well as the form of the heating itself.
Title: Mathematical Models to Investigate the Relationship between Cross-Immunity and Replacement of Influenza Subtypes
Speaker: SM Asaduzzaman, University of Victoria
Date and time:
22 Nov 2017,
9:00am -
10:00am
Location: Clearihue Building Room B017
Event type: Graduate dissertations
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Notice of the Final Oral Examination for the Degree of Doctor of Philosophy
of
SM ASADUZZAMAN
MSc (University of Western Ontario, 2011)
MSc (University of Dhaka, 2008)
BSc (University of Dhaka, 2006)
“Mathematical Models to Investigate the Relationship between Cross-Immunity and Replacement of Influenza Subtypes”
Department of Mathematics and Statistics
Wednesday, November 22, 2017
9:00 A.M.
Clearihue Building
Room B017
Supervisory Committee:
Dr. Junling Ma, Department of Mathematics and Statistics, University of Victoria (Co-Supervisor)
Dr. Pauline van den Driessche, Department of Mathematics and Statistics, UVic (Co-Supervisor)
Dr. Steve Perlman, Department of Biology, UVic (Outside Member)
External Examiner:
Dr. Viggo Andreasen, Department of Science and Environment, Roskilde University
Chair of Oral Examination:
Dr. Dzifa Dordunoo, School of Nursing, UVic
Abstract
A pandemic subtype of influenza A sometimes replaces (e.g., in 1918, 1957, 1968) but sometimes coexists (e.g., in 1977) with the previous seasonal subtype. This research aims to determine a condition for replacement or coexistence of influenza subtypes. We formulate a hybrid model for the dynamics of influenza A epidemics taking into account cross-immunity of influenza strains depending on the most recent seasonal infection. A combination of theoretical and numerical analyses shows that for very strong cross-immunity between seasonal and pandemic subtypes, the pandemic cannot invade, whereas for strong and weak cross-immunity there is coexistence, and for intermediate levels of cross-immunity the pandemic may replace the seasonal subtype.
Cross-immunity between seasonal strains is also a key factor of our model because it has a major influence on the final size of seasonal epidemics, and on the distribution of susceptibility in the population. To determine this cross-immunity, we design a novel statistical method, which uses a theoretical model and clinical data on attack rates and vaccine efficacy among school children for two seasons after the 1968 A/H3N2 pandemic. This model incorporates the distribution of susceptibility and the dependence of cross-immunity on the antigenic distance of drifted strains. We find that the cross-immunity between an influenza strain and the mutant that causes the next epidemic is 88%. Our method also gives an estimated value 2.15 for the basic reproduction number R0 of the 1968 pandemic influenza.
Our hybrid model agrees qualitatively with the observed subtype replacement or coexistence in 1957, 1968 and 1977. However, our model with the homogeneous mixing assumption significantly over estimates the pandemic attack rate. Thus, we modify the model to incorporate heterogeneity in the contact rate of individuals. Using the determined values of cross-immunity and R0, this modification lowers the pandemic attack rate slightly, but it is still higher than the observed attack rates.
Title: Math Mania at Oaklands Elementary
Date and time:
21 Nov 2017,
6:30pm -
8:00pm
Location: 2827 Belmont Ave. Victoria, BC
Event type: Education and outreach
Read full description
This Alternative Math Education event will present fun methods of teaching math and computer science concepts to children (and adults!) using games and art.
Lots of hands-on activities!
Including:
- A Sorting Network
- An Impossible Balancing Act
- Bubbles
- Mathematical Puzzles
- The Guessing Game
- Sudoku
- The Penny Game
- The Set Game
- And many more!
Title: n-th Annual Combinatorial Potlatch
Date and time:
18 Nov 2017,
10:00am -
5:00pm
Location:
Event type: Conferences and workshops
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This is the first announcement of the n-th Annual Combinatorial Potlatch, which will be hosted by the University of Victoria on Saturday, November 18, 2017 in Victoria, BC.
We are close to finalizing the program. That, and other information, will be added to the conference page soon, and will also be contained in the second announcement. Information on lodging is available now.
Main Potlatch Page:
http://buzzard.ups.edu/potlatch/index.html
2017 Conference Page:
http://faculty.wwu.edu/sarkara/potlatch2017.html
There is no advance registration required, nor any registration fee. The first talk will be mid to late morning, to allow for travel, followed by a no-host lunch, and two talks later in the afternoon. Many participants choose to stay for dinner locally.
Combinatorial Potlatches have been held for many years at various locations around Puget Sound and southern British Columbia, and are an opportunity for combinatorialists in the region to gather informally for a day of invited talks and conversation. While most who attend work in, or near, the Puget Sound basin, all are welcome.
Please forward this announcement to anyone, especially graduate students, that might be interested and are not on our list. Our apologies if you receive more than one copy of this.
Title: A Perron-Frobenius Theorem for Cocycles of Matrices/Linear Operators, Part 2
Speaker: Joseph Horan, University of Victoria
Date and time:
16 Nov 2017,
2:30pm -
3:20pm
Location: CLE A211
Event type: Dynamics seminar
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Abstract: In this second of three-ish talks, we state a theorem which
generalizes the classical Perron-Frobenius theorem to the situation of
matrix cocycles. The first portion of the talk will be dedicated to the
statement of the theorem and the importance/meaning of the hypotheses (and
where other authors used different hypotheses), and the second portion
will be a general overview/sketch of the proof of the theorem,
highlighting the important features of the proof (as opposed to the
technical details). We will also briefly see an example of how the theorem
can be applied.
Title: Math Escape
Date and time:
16 Nov 2017,
9:00am -
3:00pm
Location: Cadboro Commons, Arbutus and Queenswood rooms, UVic
Event type: Education and outreach
Read full description
Let's Talk Science and the UVic Math Department have been working together to bring you a
Math Escape! Enjoy a full day of testing your mind with card games, puzzles and 3D sculptures! Find the beauty in math!
If the grade range doesn't apply to you, we would also appreciate it if you could share these opportunity and registration links to other teachers in your schools or districts. Space is limited and registration will be closed once maximum capacity is reached. The students will come to the UVic campus for the morning and hear talks from experts in the field, meet inspirational mentors and role models and have fun with math!
Date: November 16th
Time: 9:00AM-3:00 PM
Audience: 100 students in Grades 8-10
Title: A Perron-Frobenius Theorem for Cocycles of Matrices/Linear Operators
Speaker: Joseph Horan, University Victoria
Date and time:
09 Nov 2017,
2:30pm -
3:20pm
Location: Clearihue A211
Event type: Dynamics seminar
Read full description
In this first of three-ish talks, we will recall the analogy
between powers of a single matrix and products of probably-different
matrices, and then describe how the Perron-Frobenius Theorem fits into
this situation. We will also motivate why we might care about a version of
this theorem in the more general case, and mention some preliminaries and
ingredients that we need (as well as some history of theorems of this
type). The point of the series of talks is to give an introduction,
statement, and proof idea for this theorem in the situations of matrix
cocycles, and then of linear operators on Banach spaces.
Title: The minimum number of eigenvalues of graphs
Speaker: Shahla Nasserasr, Brandon University
Date and time:
09 Nov 2017,
10:00am -
11:00am
Location: HSD A270
Event type: Discrete math seminar
Read full description
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Title: Mathematical models to investigate the relationship between cross-immunity and replacement of influenza subtypes
Speaker: Asaduzzaman, S. M, University of Victoria
Date and time:
08 Nov 2017,
2:30pm -
3:20pm
Location: DSB C124
Event type: Applied math seminar
Read full description
A pandemic subtype of influenza A sometimes replaces (e.g., in 1918, 1957, 1968) but sometimes coexists (e.g., in 1977) with the previous seasonal subtype. To determine a condition for replacement or coexistence of influenza subtypes, we formulate a hybrid model for the dynamics of influenza A epidemics taking into account cross-immunity of influenza strains depending on the most recent seasonal infection. A combination of theoretical and numerical analyses shows that for very strong cross-immunity between seasonal and pandemic subtypes, the pandemic cannot invade, whereas for strong and weak cross-immunity there is coexistence, and for intermediate levels of cross-immunity the pandemic may replace the seasonal subtype.
Cross-immunity between seasonal strains is also a key factor of our model because it has a major influence on the final size of seasonal epidemics, and on the distribution of susceptibility in the population. To determine this cross-immunity, we design a novel statistical method, which uses a theoretical model and clinical data on attack rates and vaccine efficacy among school children for two seasons after the 1968 A/H3N2 pandemic. This model incorporates the distribution of susceptibility and the dependence of cross-immunity on the antigenic distance of drifted strains. We find that the cross-immunity between an influenza strain and the mutant that causes the next epidemic is 88%. Our method also gives an estimated value 2.15 for the basic reproduction number $\mathcal{R}_0$ of the 1968 pandemic influenza.
Title: Maps Coupled on Networks, Part II
Speaker: Matteo Tanzi, University of Victoria
Date and time:
02 Nov 2017,
2:30pm -
3:20pm
Location: Clearihue A211
Event type: Dynamics seminar
Read full description
During the talks I am going to present old and new results on ergodic
theoretical properties of high-dimensional systems coupled on graphs. The
local dynamics at each node is uniformly expanding and coupled with other
nodes according to the edges of a graph.
In the first part I am going to introduce basic definitions and an
overview of some research trends on maps coupled on networks, with a
particular focus on coupled map lattices. In the second part I am going to
focus on recent developments on maps coupled on heterogeneous networks
meaning that most of the nodes make a small number of interactions, while
a few hub nodes have very high degree. For such high-dimensional systems
there is a regime of the interaction strength for which the coupling is
small for poorly connected systems, and large for the hub nodes. In
particular, global hyperbolicity might be lost. We show that, under
certain hypotheses, the dynamics of hub nodes can be very well
approximated by a low-dimensional system for exponentially long time in
the size of the network and that the system exhibit hyperbolic behaviour
in this time window. Even if this describes only a long transient, we
argue that this is the behaviour that one expects to observe in
experiments. Such a description allows us to establish the emergence of
macroscopic behaviour such as coherence of dynamics among hubs of the same
connectivity layer (i.e. with the same number of connections).
Title: Envelope Seminar
Speaker: Adam Dor-on, University of Victoria
Date and time:
02 Nov 2017,
1:00pm -
2:00pm
Location: CLE C116
Event type: Operator theory seminar
Read full description
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Title: Threshold Tolerance Graphs and Their Complements
Speaker: Ross McConnell, Colorado State University
Date and time:
02 Nov 2017,
10:00am -
11:20am
Location: HSD A270
Event type: Discrete math seminar
Read full description
A graph is a threshold tolerance graph if each vertex can be assigned a weight and a threshold such that two vertices are adjacent if the sum of their weights exceeds at least one of their thresholds. An interval graph is the graph of intersections of a set of intervals on a line. Interval graphs have a rich and well-known set of structural properties. The complements of threshold tolerance graphs are a generalization of interval graphs, and they can each be modeled with a set of intervals by modifying its interpretation. We get an O(n^2) algorithm for recognizing tolerance graphs and their complements by generalizing techniques for recognizing interval graphs. When a graph is in the class, we show how to construct the intervals or the weights and thresholds. This improves an O(n^4) bound given by Monma, Reed and Trotter.
Title: Index Theory on the Mishchenko bundle (part 2 of 2)
Speaker: Valerio Proietti, University of Copenhagen
Date and time:
01 Nov 2017,
3:30pm -
4:50pm
Location: CLE D131
Event type: Operator theory seminar
Read full description
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Title: Statisticians at Work: Inspiration, Aspiration, Ambition
Speaker: C. F. Jeff Wu, School of Industrial and Systems Engineering, Georgia Institute of Technology
Date and time:
30 Oct 2017,
3:30pm -
4:20pm
Location: MacLaurin Building, room D103
Event type: PIMS lectures
Read full description
A key measure of the maturity and quality of a scientific community is how it judges and values accomplishments and (or versus) scholarship. To address this question, I will describe the motivation or drive for accomplishments and/or scholarship at three levels: inspiration, aspiration, ambition. They represent different (but not necessarily exclusive) mindsets or modi operandi. I will use several prominent examples in statistics history to explain or illustrate the acts of inspiration, aspiration, and ambition. They include: Pearson’s arguments with Fisher and with Yule, some breakthrough work of Fisher, Neyman, Tukey, Box, Efron, etc. Then I will share some thoughts on what are good or bad mathematical statistics work. Throughout this talk, I will use the “lens” of inspiration, aspiration, and ambition in making my examinations, remarks and suggestions.
C. F. Jeff Wu is Professor and Coca Cola Chair in Engineering Statistics at the School of Industrial and Systems Engineering, Georgia Institute of Technology. He was the first academic statistician elected to the National Academy of Engineering (2004); also a Member (Academician) of Academia Sinica (2000). A Fellow of American Society for Quality, Institute of Mathematical Statistics, of INFORMS, and American Statistical Association. He received the COPSS (Committee of Presidents of Statistical Societies) Presidents’ Award in 1987, the COPSS Fisher Lecture Award in 2011, the Deming Lecture Award in 2012, the inaugural Akaike Memorial Lecture Award in 2016, the George Box Medal from Enbis in 2017, and numerous other awards and honors. He has published more than 170 research articles and supervised 45 Ph.D.'s. He has published two books "Experiments: Planning, Analysis, and Parameter Design Optimization" (with Hamada) and “A Modern Theory of Factorial Designs” (with Mukerjee).
Download poster (PDF file)
Title: Envelope Seminar
Speaker: Adam Dor-on, University of Victoria
Date and time:
30 Oct 2017,
11:30am -
12:50pm
Location: COR A132
Event type: Operator theory seminar
Read full description
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Title: What makes an irredundant set maximal?
Speaker: Linda Nielson, University of Victoria
Date and time:
26 Oct 2017,
10:00am -
11:20am
Location: HD A270
Event type: Discrete math seminar
Read full description
Linda Neilson will talk about the paper "What makes an irredundant set maximal?”, by Cockayne, Grobler, Hedetniemi, and McRae, which was published in 1997.
Title: Cascade Topology Seminar
Date and time:
21 Oct
to
22 Oct 2017,
9:30am -
4:30pm
Location: University of Victoria, DTB A102
Event type: Conferences and workshops
Read full description
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Title: Maps Coupled on Networks
Speaker: Matteo Tanzi, University of Victoria
Date and time:
19 Oct 2017,
2:30pm -
3:20pm
Location: Clearihue A211
Event type: Dynamics seminar
Read full description
During the talks I am going to present old and new results on ergodic
theoretical properties of high-dimensional systems coupled on graphs. The
local dynamics at each node is uniformly expanding and coupled with other
nodes according to the edges of a graph.
In the first part I am going to introduce basic definitions and an
overview of some research trends on maps coupled on networks, with a
particular focus on coupled map lattices. In the second part I am going to
focus on recent developments on maps coupled on heterogeneous networks
meaning that most of the nodes make a small number of interactions, while
a few hub nodes have very high degree. For such high-dimensional systems
there is a regime of the interaction strength for which the coupling is
small for poorly connected systems, and large for the hub nodes. In
particular, global hyperbolicity might be lost. We show that, under
certain hypotheses, the dynamics of hub nodes can be very well
approximated by a low-dimensional system for exponentially long time in
the size of the network and that the system exhibit hyperbolic behaviour
in this time window. Even if this describes only a long transient, we
argue that this is the behaviour that one expects to observe in
experiments. Such a description allows us to establish the emergence of
macroscopic behaviour such as coherence of dynamics among hubs of the same
connectivity layer (i.e. with the same number of connections).
Title: General spectral graph theory: The inverse eigenvalue problem of a graph
Speaker: Jephian Lin, University of Victoria
Date and time:
19 Oct 2017,
10:00am -
11:20am
Location: HSD A270
Event type: Discrete math seminar
Read full description
Spectral graph theory usually studies the relations between a graph and a corresponding matrix, which can be the adjacency matrix, the Laplacian matrix, the normalised Laplacian matrix, or other matrices. For each graph G, these matrices belong to the family S(G) of symmetric matrices whose i,j-entry with i != j is nonzero whenever {i,j} is an edge and zero otherwise. (Diagonal entries can be either zero or nonzero.) The inverse eigenvalue problem studies the ``general property'' of S(G) and aims to find all possible spectra appeared in S(G). We will go through many graph concepts such as the diameter, the domination number, and the graph minor theory, and then discuss their relations to matrices.
Title: Index Theory on the Mishchenko bundle (part 1 of 2)
Speaker: Valerio Proietti, University of Copenhagen
Date and time:
18 Oct 2017,
3:30pm -
4:50pm
Location: CLE D131
Event type: Operator theory seminar
Read full description
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Title: The Obesity Paradox of Hemodialysis
Speaker: Robert Steacy, University of Victoria
Date and time:
18 Oct 2017,
2:30pm -
3:20pm
Location: DSB C124
Event type: Applied math seminar
Read full description
Abstract: Over two million people worldwide, with kidney failure, go for renal hemodialysis,
usually three sessions per week, of four hours each. It has been known for forty years,
and studied intensely for the last twenty, that of patients on hemodialysis, those who are
obese (BMI > 30) live significantly longer than those who are of average weight. There is now a
mountain of empirical evidence for this phenomenon, which has come to
be known as the Obesity Paradox of Hemodialysis. However, very little is understood.
I will describe the progress which I have made on this problem.
