Computational Aspects in Finance and Actuarial Sciences
2022-07-08 - 2022-07-09 | University of Prince Edward Island, Charlottetown, Prince Edward Island, Canada
The AARMS CRG Conference on Computational Aspects in Finance and Actuarial Sciences will be held July 8-9 in PEI, Canada. This conference is mainly hosted by the Atlantic Association for Research in Mathematical Sciences (AARMS) collaborative research group (CRG) and the School of Mathematical and Computational Sciences (SMCS) at University of Prince Edward Island (UPEI), Canada, and is a unique venue that brings together leaders in finance, and actuarial sciences, across disciplines, and across borders, tackling very important and timely topics in finance and actuarial sciences. Our intention for this conference is to have a broad scope in terms of applications in Finance and Actuarial Sciences but we would like to put emphasis on numerical and computational issues (including trendy topics such as machine learning algorithms in finance and insurance, but also more traditional methods such as numerical solutions for PDEs, Monte Carlo simulations, etc). The conference will include a dynamic program with high quality speakers focusing on innovative research, policy discussions, and business challenges and successes.
ZOOM link: https://us06web.zoom.us/u/kUOl82t1s

Canadian Undergraduate Mathematics Conference / Congrès canadien des étudiant(e)s en mathématiques
2022-07-13 - 2022-07-17 | Université Laval, 2325 Rue de l'Université, Québec, Québec, G1V 0A6, Canada
The Canadian Undergraduate Mathematics Conference (CUMC) is a national conference organized each summer by undergraduate students for undergraduate students at different institutions across Canada.
The CUMC is an opportunity for students to explore mathematics outside their usual surroundings and spark their interest in areas they have not yet been exposed to. Indeed, the core of the gathering consists of a series of talks given by participants. The conference therefore provides a unique chance for students to present what they find most fascinating and exciting, as well as to practice their expository skills in an inclusive and noncompetitive environment. As a national conference, the CUMC is a bilingual event. Moreover, the event seeks to promote diversity within the field of mathematics itself, by offering keynote lectures in both pure and applied fields.
The CUMC is primarily organised by a local organising committee at the host institution, under the aegis of Studc.

AARMS Geophysical Inverse Problems Discussion
2022-07-15 13:30 - 14:30 UTC | Zoom seminar
Friday, July 15, 2022 @ 1:30 pm – 2:30 pm (Atlantic time)
Bijani et al., 2017, Physical-property-, lithology- and surface-geometry-based joint inversion using Pareto Multi-Objective Global Optimization.
If you are unable to access the paper through that link, please email the organizer (and co-author on the paper) for a copy (plelievre@mta.ca).
This paper introduces the concept of multi-objective optimization and Pareto-optimality. In this work, instead of attempting to select a single value for the regularization parameter, the methods sample the entire Pareto-curve (Tikhonov curve), or for more than two objective functions the Pareto-(hyper)surface. The challenge is then deciding how to visualize and otherwise explore all the possible models provided, extract useful information from them, and make reasonable interpretations.
Connection details will be available on the organizer’s website.

AARMS Geophysical Inverse Problems Discussion
2022-07-29 13:30 - 14:30 UTC | Online via Zoom
Lelièvre et al., 2012, Joint inversion of seismic traveltimes and gravity data on unstructured grids with application to mineral exploration.
https://library.seg.org/doi/10.1190/geo2011-0154.1

If you are unable to access the paper through that link, please email the organizer (and co-author on the paper) for a copy (plelievre@mta.ca).
This paper looks at various different methods to enforce the similarity of the different models in a joint inversion. This paper will help us discuss previous themes in relation to joint inversion, including the deterioration of numerical behavior for particular objective functions, constructing piecewise-constant models, and determining the value of the regularization parameter(s).

Friday, July 29, 2022 @ 1:30 pm – 2:30 pm (Atlantic time)

Connection details will be published on the organizer’s website:
https://www.esd.mun.ca/~peter/AARMS-CRG.html

Symmetry, Invariants, and their Applications: A Celebration of Peter Olver’s 70th Birthday
2022-08-03 - 2022-08-05 | Halifax, Halifax, Nova Scotia, Canada
This is a proposal for a workshop on symmetry, invariants, and their applications in celebration of Peter Olver’s 70th birthday. Transformation and groups are an omnipresent concept in nature, science, and art. Many biological, chemical, physical, or man-made structures exhibit symmetries as a fundamental design principle or as an essential aspect of their functioning. Symmetry groups also occur in a wide variety of modern applications including computer vision, archaeology, numerical integration, and neural networks, differential equations, geometry, and applied mathematics.
During his prolific career, Peter J. Olver played an important role in the development of symmetry group methods to differential equations, geometry, and applied mathematics.The purpose of the workshop is to bring together leading experts, promising younger researchers, and graduate students from around the world to assess the rapid advances occurring in the field of symmetries and invariants, and to evaluate the most promising directions of future developments.

Intersection of Microlocal Analysis, Harmonic Analysis, and Inverse Problems: A conference in honor of Allan Greenleaf
2022-08-15 - 2022-08-17 | University of Rochester, 500 Joseph C. Wilson Blvd, Rochester, NY, United States
The objective of the conference is to bring together an international group of experts in three areas: microlocal analysis, inverse problems and harmonic analysis. There will be 19 internationally recognized researchers in those subjects, each invited to give a lecture. There has recently been great progress in all these areas, with mutual benefits, and no end in sight. With this conference we hope to foster interaction and collaboration among speakers and other participants from the three different areas. Furthermore, the conference will take the opportunity to honor the research achievements of Professor Allan Greenleaf, who has made fundamental contributions to many of the topics covered by this conference.

East Coast Combinatorics Conference
2022-08-17 - 2022-08-18 | University of Prince Edward Island, Charlottetown, Prince Edward Island, Canada
The East Coast Combinatorics Conference is an annual conference designed to support and bring together researchers in mathematics and computer science interested in all aspects of combinatorics. A unique feature is the workshop-like atmosphere which encourages active collaboration and participation of faculty and students while highlighting major theoretical advances and applications in the area. In addition to plenary talks, the conference features contributed talks presented by faculty, students, and post-docs.

34th Canadian Conference on Computational Geometry
2022-08-25 - 2022-08-27 | Ryerson University, Toronto, Ontario, Canada
The Canadian Conference on Computational Geometry (CCCG) is a forum to disseminate and discuss theoretical and applied results in discrete and computational geometry.
Computational geometry is concerned with the design of efficient algorithms, the development of software, and the study of the mathematical foundations of computational problems whose formulation involves geometric constraints. The field is motivated by problems from a broad range of application areas, as diverse as computer graphics and animation, computer vision, computer-aided design and manufacturing, geographic information systems, pattern recognition, wireless communications, robotics, protein folding, urban planning, graph drawing, or statistical analysis. The 34th Canadian Conference on Computational Geometry will take place in August 2022 in Toronto, ON.

Science Atlantic Mathematics, Statistics, and Computer Science Conference
2022-10-21 - 2022-10-22 | Mount Allison University, Sackville, New Brunswick, Canada
The Science Atlantic Mathematics, Statistics, and Computer Science Conference is held each October and provides an opportunity for students to present their research and to learn about other undergraduate research projects across the region in a supportive and inclusive environment. Undergraduate students are also able to participate in team-based mathematics and programming competitions. The conference additionally provides a valuable opportunity for undergraduate students to meet potential graduate supervisors, and is the only venue for faculty members from across Atlantic Canada to network and share ideas and information related to research and mentorship.

University of New Brunswick Data Challenge 2022
2022-11-18 | University of New Brunswick (Fredericton Campus), Fredericton, New Brunswick, Canada
The Data Challenge will bring together three competitive events, Data Visualization (7th Annual), Data Analytics (3rd Annual), and Data Sprint (3rd Annual) on Nov. 18, 2022, in a hybrid format – virtually and in person! Take up the challenge and demonstrate the power of data, with the flexibility to take part remotely.
Participants and teams will have the chance to showcase their ability to tell a story driven by data in three unique competitive formats. Teams can participate in all three competitive events. It is an ideal setting for citizens to get engaged, meet leaders in academia, government, and private organizations, and explore the world of data science.

Atlantic Graph Theory Seminar: Sebastian Cioaba, University of Delaware
2022-11-30 15:30 - 16:30 UTC | Online via Zoom
Addressing graphs and hypergraphs
In 1970s, Ron Graham and Henry Pollak introduced the notion of graph addressing which is a labeling of the vertices of an undirected graph by words of the same length over the alphabet {0,1,*} such that the distance between any two vertices equals the number of positions in their labels/addresses where one vertex has a 0 and the other one has a 1. The minimum of length of such words has been investigated by various people and is closely related to the partition of the edge set of the graph into bicliques (complete bipartite subgraphs). In this talk, I will describe some recent results related to this parameter for various families of graphs and the corresponding problem for hypergraphs.
Zoom info:

https://us02web.zoom.us/j/87564743456?pwd=[REDACTED]
Meeting ID: 875 6474 3456
Passcode: [REDACTED]

The 19th Seminar on Commutative Algebra and related topics
2023-01-07 - 2023-01-12 | Institute for Research in Fundamental Sciences (IPM) Tehran, Iran, Tehran, Iran, Islamic Republic of
Every year the school of mathematics of IPM-Tehran organizes a seminar and workshop to introduce the research topics in the main streams of “Algebraic Geometry, Commutative algebra and Combinatorial commutative algebra” to young researchers and PhD students, and encourage them to collaborate in teams led by well-known mathematicians in this area. This year we have paid special attention to inviting regional speakers, as well as international leaders. Our list of speakers highlights female mathematicians, and the areas represented are those in which there is regional expertise, hopefully leading to new collaborations.
The conference is preceded by a workshop on Lefschetz properties and connections to algebra, geometry and combinatorics. The workshop will feature the leading questions in the area, and the lectures will be delivered by some of the main players in this field.

Atlantic Graph Theory Seminar: Pawel Pralat, Metropolitan University of Toronto
2023-01-11 15:30 - 16:30 UTC | Online via Zoom
An Unsupervised Framework for Comparing Graph Embeddings
The goal of many machine learning applications is to make predictions or discover new patterns using graph-structured data as feature information. In order to extract useful structural information from graphs, one might want to try to embed it in a geometric space by assigning coordinates to each node such that nearby nodes are more likely to share an edge than those far from each other. There are many embedding algorithms (based on techniques from linear algebra, random walks, or deep learning) and the list constantly grows. As a result, selecting the best embedding is a challenging task and very often requires domain experts. Our general framework assigns the divergence score to each embedding which, in an unsupervised learning fashion, distinguishes good from bad embeddings. In order to benchmark embeddings, we generalize the Chung-Lu random graph model to incorporate geometry.

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Meeting ID: 823 0601 7918
Passcode: [REDACTED]

Dalhousie-AARMS AAMP Seminar: Andrea Bertozzi (UCLA)
2023-01-13 16:00 - 17:00 (America/Halifax) | Dalhousie University, Halifax, Nova Scotia, Canada
Title: Energy Minimizing Surface Tension Configurations for Microparticles
Abstract: An important area of microfluidics is the creation and manipulation of small droplets. This is commonly done using microchannels or electrowetting. Recently a new method is proposed to create templated droplets using amphiphilic microparticles. These particles are observed to hold nearly equal volumes of aqueous liquid when dispersed in an oil–water mixture. However a theory for this behavior is lacking. In this paper, we present a mathematical model based on minimizing the surface tension energy of a system of particles. By analyzing this model, we demonstrate that certain key properties of the particle guarantee the formation of small droplets within a volume range unique to the particle. We also look at statistical dynamics of pairwise exchange of fluids between particles for which the system can reach equilibrium. We show examples of how such particles are useful for applications such asbiological assays and measurement of chemical secretions from single cells.

The Dalhousie-AARMS Analysis-Applied Math-Physics Seminar takes place on Fridays from 4 – 5 pm Atlantic Time over Zoom and in Chase 227. If you would like to attend, please email the organizers for connection details.

Atlantic Graph Theory Seminar: Jane (Pu) Gao, University of Waterloo
2023-01-18 15:30 - 16:30 UTC | Online via Zoom
Conditions for perfect matchings in random sparse bipartite graphs
Given a uniformly random sparse matrix A, with specified number of nonzero entries in columns and rows, we determine when A has full row rank over a finite field. As a corollary, by considering A as the adjacency matrix of a bipartite graph, our result determines the conditions for the existence of a perfect matching in various models of random sparse bipartite graphs. We will explore some useful insight from statistical physics that guides our probabilistic combinatorial proof. This is joint work with Coja-Oghlan, Hahn-Klimroth, Lee, Mueller and Rolvien.

Join Zoom Meeting
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Meeting ID: 823 0601 7918
Passcode: [REDACTED]

Dalhousie-AARMS AAMP Seminar: Chamsol Park (Johns Hopkins University)
2023-01-20 16:00 - 17:00 (America/Halifax) | Dalhousie University, Halifax, Nova Scotia, Canada
Title: Eigenfunction restriction estimates on curves with nonvanishing geodesic curvatures

Abstract: Studying eigenfunctions of the Laplace-Beltrami operator on compact Riemannian manifolds (without boundary) is one of the interesting topics in Harmonic Analysis. One way to study them is to consider the L^p estimates of the eigenfunctions restricted to submanifolds. In this talk, we briefly summarize previous results and would like to talk about the logarithmic improved analogue for the restriction to curves with nonvanishing geodesic curvatures, in the presence of nonpositive sectional curvatures in the manifolds. If time permits, we will discuss some applications and open problems for the Schrodinger counterparts.

The Dalhousie-AARMS Analysis-Applied Math-Physics Seminar takes place on Fridays from 4 – 5 pm Atlantic Time over Zoom and in Chase 227. If you would like to attend, please email the organizers for connection details.

Dalhousie-AARMS AAMP Seminar: Alex Barnett (Flatiron Institute, NYC)
2023-01-27 16:00 - 17:00 (America/Halifax) | Dalhousie University, Halifax, Nova Scotia, Canada
Title: Equispaced Fourier representations for efficient Gaussian process regression from a billion data pointsAbstract: Gaussian process regression is widely used in geostatistics, time-series analysis, and machine learning. It infers an unknown continuous function in a principled fashion from noisy measurements at $N$ scattered data points. The prior on the function is Gaussian, with covariance given by some user-chosen translationally invariantkernel. Yet $N$ has been limited to about $10^6$, even with modern low-rank methods. Focusing on low spatial dimension (1–3), we present a GP regression method using kernel approximation by an equispaced quadrature grid in the Fourier domain. This enables the iterative solution of a smaller Toeplitz linear system, exploiting both the FFT and the nonuniform FFT to give ${mathcal O}(N)$ cost. The result is often one to two orders of magnitude faster than state of the art methods, and enables cheap massive-scale regressions. For example, for a 2D Mat’ern-3/2 kernel and $N = 10^9$ points, the posterior mean function is found to 3-digit accuracy in two minutes on a desktop.Joint work with Philip Greengard (Columbia) and Manas Rachh (Flatiron Institute)
The Dalhousie-AARMS Analysis-Applied Math-Physics Seminar takes place on Fridays from 4 – 5 pm Atlantic Time over either Zoom and/or in Chase 227 depending on the speaker. If you would like to attend, please email the organizers for connection details.

Atlantic Graph Theory Seminar: Jason Brown, Dalhousie University
2023-02-08 15:30 - 16:30 UTC | Online via Zoom
Colourings, Polynomials and Roots
A lot has happened since graph colourings first arose as an applied problem in cartography – do four colours always suffice to distinguish countries when colouring a map? Along the way to the proof, the related enumeration function to count the number of k-colourings was proposed. While the latter didn’t help much in the quest for the Four Colour Theorem, it did lead to a fascinating branch of graph theory, namely chromatic polynomials. While polynomials are the simplest of functions, their properties can take you deep within mathematics. In this talk I will describe some recent result on chromatic polynomials and their offshoots, connecting to commutative algebra as well as real and complex analysis. And on our trip, we visit with some old friends, including Charles Hermite, Jacques Sturm, and Carl Gauss.
Meeting ID: 831 4765 9865
Passcode: [REDACTED]

Dalhousie-AARMS AAMP Seminar: Victor Ivrii (U. Toronto)
2023-02-10 16:00 - 17:00 (America/Halifax) | Dalhousie University, Halifax, Nova Scotia, Canada
Title + Abstract: TBD
The Dalhousie-AARMS Analysis-Applied Math-Physics Seminar takes place on Fridays from 4 – 5 pm Atlantic Time over either Zoom and/or in Chase 227 depending on the speaker. If you would like to attend, please email the organizers for connection details.

Atlantic Graph Theory Seminar: Jérémie Turcotte, Université de Montréal
2023-02-15 15:30 - 16:30 UTC | Online via Zoom
Progress towards the Burning Number Conjecture
The burning number b(G) of a graph G is the smallest integer k such that G can be covered by k balls of radii respectively 0,…,k-1, and was introduced independently by Brandenburg and Scott at Intel as a transmission problem on processors and Bonato, Janssen and Roshanbin as a model for the spread of information in social networks. The Burning Number Conjecture claims that b(G)<=lceilsqrt{n}rceil, where n is the number of vertices of G. This bound is tight for paths. The previous best bound for this problem, by Bastide et al., was b(G)<= sqrt{frac{4n}{3}}+1. We prove that the Burning Number Conjecture holds asymptotically, that is b(G)<= (1+o(1))sqrt{n}. Following a brief introduction to graph burning, this talk will focus on the general ideas behind the proof.
Meeting ID: 885 9352 1895
Passcode: [REDACTED]

Minicourse: Group Graded Azumaya Algebras and Generic Constructions
2023-02-17 11:00 - 2023-02-22 12:00 UTC | Memorial University (St. John’s Campus), St. John's, Newfoundland and Labrador, Canada
Taught by Professor Eli Aljadeff, Technion University, Israel
The main theme of this mini-course is gradings by finite groups on finite-dimensional algebras. Similar to the classical situation of ungraded algebras, we will be interested in finite-dimensional graded simple algebras and finite-dimensional graded division algebras. An important role is played by a generalization of central simple algebras, called Azumaya algebras.
Our main tool will be polynomial identities and, in particular, graded polynomial identities. This tool will allow us to construct generic graded Azumaya algebras.
In the first lecture of the mini-course, as a part of the motivation to discuss group graded algebras, I will recall some classical topics such as division algebras, Brauer groups, crossed products and Galois cohomology. Then I will introduce G-graded polynomial identities, where G is a finite group, and discuss generic constructions. In particular, for an arbitrary finite-dimensional G-graded simple algebra A over an algebraically closed field F of characteristic 0, I will construct a generic G-graded Azumaya algebra from which one can obtain by specialization all forms of A in the sense of Galois descent.
As a key application, I will discuss the following problem. It is not difficult to see that for any finite group G, finite-dimensional G-graded division algebras are G-graded simple and they remain G-graded simple upon any extension of the field of scalars.
We will be interested in the opposite direction. Unlike the situation in the ungraded case, where the algebras of n × n matrices always admit forms which are division algebras, this is not generally true in the setting of G-graded algebras.
Suppose that A is a finite-dimensional G-graded simple algebra over an algebraically closed field F. One of the goals of these lectures is to provide necessary and sufficient conditions on the graded structure of A under which A admits forms that are G-graded division algebras. In particular we show that A must be a G-graded simple algebra for which the corresponding generic G-graded simple algebra is a G-graded division algebra.
The lectures will be delivered during three time periods, as shown below. They will take place at the St. John’s campus of Memorial University and will be broadcast via Webex. All the times are in Newfoundland Time (NST=UTC-3:30).
Friday, February 17, 11-12 am, room A-1045/1046
Monday, February 20, 11-12 am, room A-1045/1046
Wednesday, February 22, 11-12 am, room A-1045/1046
The lectures will be available online via Webex. Contact the organizer for details

Atlantic Graph Theory Seminar: Isaac McMullin and Ian George, Dalhousie University
2023-03-01 15:30 - 16:30 UTC | Online via Zoom
Speaker 1: Isaac McMullin
Existence of Optimal Split Reliability Polynomials
One of the most common models of robustness of a graph against random failures has all vertices operational, but the edges independently operational with probability p. On one hand, one can ask for the probability that all vertices can communicate (all-terminal reliability) while on the other hand, we can ask that two specific vertices (or terminals) can communicate with each other (two-terminal reliability). While both of these questions have been well-studied, they are both increasing functions of the edge probability. One new approach is split reliability, where for two fixed vertices s and t, we consider the probability that every vertex communicates with one of s or t, but not both. The split reliability of G is a polynomial function of p that for connected graphs is 0 both at p=0 and at p=1. In this presentation, we explore the existence for fixed numbers n>=2 and m>=n-1 of an optimal connected (n,m)-graph G_(n,m) for split reliability, that is, a connected graph with n vertices and m edges for which for any other such graph H, the split reliability of G_(n,m) is at least as large as that of H, for all values of p in [0,1]. Unlike the similar problems for all-terminal and two-terminal reliability, where only partial results are known, we completely solve the issue for split reliability, where we show that there is an optimal (n,m)-graph for split reliability if and only if n<=3, m=n-1, or n=m=4.

Speaker 2: Ian George
Degree Polynomials of Graphs
In this talk we introduce the Degree Polynomial of a graph. This polynomial is defined to be the generating function of the sequence (a_0, a_1, a_2, …) where a_k is the number of vertices of degree k in a graph. Little has been published about this polynomial other than its behaviour under graph operations. We will explore some basic properties of this polynomial, and see what information it encodes about a graph. Then we will discuss the roots of degree polynomials, or degree roots, giving some bounds and density results. Along the way, the degree polynomials and degree roots for certain families of graphs will be highlighted.

The talks will be held in room 227 in the Chase building at Dalhousie, and streamed via zoom
Join Zoom Meeting
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Meeting ID: 864 1523 0827
Passcode: [REDACTED]

Atlantic Graph Theory Seminar: Lucas Mol, Thomson Rivers University
2023-03-08 15:30 - 16:30 UTC | Online via Zoom
Avoiding additive powers in words
A word is a sequence of symbols taken from some finite alphabet. A square is a word of the form xx, where x is a nonempty word. It is well-known that there are infinite words over an alphabet of size 3 that contain no squares. Suppose now that the alphabet is some finite subset of the integers. An additive square is a word of the form xx’, where x and x’ have the same nonzero length and the same sum. Additive cubes, fourth powers, etc., are defined similarly. We present a method for proving that certain types of infinite words contain no additive k-powers. This is joint work with James Currie, Narad Rampersad, and Jeffrey Shallit.

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Meeting ID: 864 1523 0827
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Dalhousie-AARMS AAMP Seminar: Katrina Morgan (Northwestern University)
2023-03-10 16:00 - 17:00 (America/Halifax) | Dalhousie University, Halifax, Nova Scotia, Canada

Automorphisms And Derivations In Affine Algebraic Geometry
2023-03-13 - 2023-03-17 | Memorial University (St. John’s Campus), St. John's, Newfoundland and Labrador, Canada
Mini-course by Professor Leonid Makar-Limanov, Wayne University, USA
Brief description of the mini course
After this course you will know the proofs of several classical theorems of Affine Algebraic Geometry. The original proofs of these theorems were quite involved and a much longer course would be needed for their exposition.
In the first lecture we will discuss the theorems of Heinrich Jung and Rudolf Rentschler. The first one describes all invertible transformations of the plane by polynomials and the second all generalized shifts of the plane. Algebraically speaking, Jung’s theorem describes all automorphisms of the ring of polynomials with two variables and Rentschler theorem describes all subgroups of this group which are isomorphic to the group of complex numbers under addition. If we have time, we will discuss the groups of polynomial automorphisms of several other surfaces.
The second lecture is devoted to the following topic: if a cylinder is given, is it possible to recover the base of this cylinder. In general the answer is no, but we discuss two cases when this is possible. We show that if the cylinder over a curve is given then we can recover this curve (this is the theorem of Shreeram Abhyankar, Paul Eakin, and William Heinzer). If the cylinder over a surface is isomorphic to a three-dimensional space then the surface is isomorphic to a plane (this is a theorem of Takao Fujita).
Here is an algebraic translation:
If A is an integral domain of transcendence degree one and A[x1, x2,…, xn] is given, we can recover A up to an isomorphism. If A is an integral domain of transcendence degree two and A[x] is isomorphic to C[y1,y2,y3] then A is isomorphic to C[z1,z2]. The main tool used in these two lectures is locally nilpotent derivations.
In the third lecture we prove one of the most famous theorems in affine algebraic geometry, the AMS Theorem (after Abhyankar, Tsuong-tsieng Moh, Masakazu Suzuki): any smooth “good” embedding of a line to a plane is the image of a coordinate line under an automorphism of the plane. Algebraically, this means the following: if two polynomials f(t), g(t)∈ C[t] generate C[t] then the smaller of the degrees of f(t), g(t) divides the larger of the degrees of f(t), g(t). The main tool here is a new algorithm for finding an irreducible dependence between two polynomials in one variable.
The lectures will be delivered during three time periods, as shown below. They will take place at the St. John’s campus of Memorial University and will be broadcast via Webex. All the times are in Newfoundland Time (NST=UTC-3:30).
Monday, March 13th: TBA
Tuesday, March 14th: TBA
Thursday, March 16th: TBA
The lectures will be available online via Webex. The details will be given later. Contact the organizers for more information: Mikhail Kotchetov <mikhail@mun.ca>; Yuri A Bakhturin <bahturin@mun.ca>

Atlantic Graph Theory Seminar: Caleb Jones and Rylo Ashmore (Memorial University)
2023-03-15 15:30 - 16:30 UTC | Online via Zoom
Speaker 1: Caleb Jones, Memorial University

Title: Extending Graph Burning to Hypergraphs

Abstract:
We introduce a round-based model much like graph burning which applies to hypergraphs. The rules for this new model are very natural,and generalize the original model of graph burning. We also introduce a variant called lazy hypergraph burning, along with a new parameter, the lazy burning number. Interestingly, lazily burning a graph is trivial, while lazily burning a hypergraph can be quite complicated. Moreover, the lazy burning model is a useful tool for analyzing the round-based model on hypergraphs. We obtain bounds on the burning number and lazy burning number of a hypergraph in terms of its parameters.

Speaker 2: Rylo Ashmore, Memorial University

Title: Herding Cats Stuck in Trees.

Abstract:
In the game of Cat Herding on a graph, one player (the herder) will omnipresently delete edges, while the other player (the cat) is on a vertex of the graph, and will move along any path to a new vertex. Eventually, the cat is isolated on a single vertex, and the cat’s objective is to delay this event, while the herder tries to hasten it. In an optimally played game, the number of cuts the herder made to isolate the cat is the cat number of the graph. In this talk, we will investigate this graph parameter for both dense and sparse graphs. We will see an argument that the asymptotic behaviour of the cat number of complete graphs is n^2/3. We also look at an unexpected connection between cat herding on trees and Fibonacci numbers. In particular, we will see that trees with maximum cat number amongst graphs with n vertices have cat number asymptotically log_φ (n).

Zoom link: https://us02web.zoom.us/j/86415230827?pwd=[REDACTED]

Meeting ID: 864 1523 0827
Passcode: [REDACTED]

Dalhousie-AARMS AAMP Seminar: Milivoje Lukic (Rice U.)
2023-03-17 16:00 - 17:00 (America/Halifax) | Dalhousie University, Halifax, Nova Scotia, Canada
Title: Universality limits for orthogonal polynomialsAbstract: It is often expected that the local statistical behavior ofeigenvalues of some system depends only on its local properties; forinstance, the local distribution of zeros of orthogonal polynomials shoulddepend only on the local properties of the measure of orthogonality. Thisphenomenon is studied using an object called the Christoffel-Darbouxkernel. The most commonly studied case is known as bulk universality,where the rescaled limit of Christoffel-Darboux kernels converges to thesine kernel.In this talk, we will survey this subject, prior results, and a recentresult which gives for the first time a completely local sufficientcondition for bulk universality. The new approach is based on a matrixversion of the Christoffel-Darboux kernel and the de Branges theory ofcanonical systems, and it applies to other self-adjoint systems with 2×2transfer matrices such as continuum Schrodinger and Dirac operators.The talk is based on joint work with Benjamin Eichinger (TechnicalUniversity Wien) and Brian Simanek (Baylor University).
The Dalhousie-AARMS Analysis-Applied Math-Physics Seminar takes place on Fridays from 4 – 5 pm Atlantic Time over either Zoom and/or in Chase 227 depending on the speaker. If you would like to attend, please email the organizers for connection details.

Atlantic Graph Theory Seminar: Mohammad Salavatipour, U. Alberta
2023-03-22 15:30 - 16:30 UTC | Online via Zoom
Approximation Schemes for Resource Minimization for Fire Containment
Resource Minimization Fire Containment (RMFC) is a natural model for optimal inhibition of
harmful spreading phenomena on a graph. In the RMFC problem on trees, we are given an undirected
tree G, and a vertex r where the fire starts at, called root. At each time step, the firefighters
can protect up to B vertices of the graph while the fire spreads from burning vertices to all their
neighbors that have not been protected so far. The task is to find the smallest B that allows for
saving all the leaves of the tree. The problem is hard to approximate up to any factor better than 2
even on trees unless P = NP.
In this talk we present an asymptotic QPTAS for RMFC on trees. More specifically, let eps > 0,
and F be an instance of RMFC where the optimum number of firefighters to save all the leaves is
OPT(F). We present an algorithm which uses at most ceil(1 + eps )OPT(F)rceil many firefighters at each
time step and runs in time n^O(loglog n). This suggests that the existence of an asymptotic PTAS is
plausible especially since the exponent is O(log log n).
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Atlantic Graph Theory Seminar: Calum MacRury, University of Toronto
2023-03-29 15:30 - 16:30 UTC | Online via Zoom
Approximation Schemes for Resource Minimization for Fire Containment
The semi-random graph process is an example of an adaptive process for constructing a graph in which random edges are added step by step. It is adaptive in that there is an online algorithm which has partial control over which random edges are added. Through intelligent decision-making, the objective of the algorithm is to force the graph to satisfy a fixed graph property with high probability in as few rounds as possible. We first provide upper and lower bounds on the performance of an optimal algorithm when the property corresponds to being Hamiltonian or to containing a perfect matching. This part of the talk is based on joint works with Pawel Pralat and Jane Gao.Afterwards, we introduce a formal definition of an adaptive random graph process which generalizes both the semi-random graph process, as well as the Achlioptas process. In this model, we define a condition called edge-replaceability which we prove is sufficient for a property to have a sharp threshold. Intuitively, a property has a sharp threshold if the optimal algorithm’s “success probability” transitions from almost $0$ to almost $1$ in a negligible number of steps. We apply our result to the semi-random graph process to show that the properties of being Hamiltonian and of containing a perfect matching each have a sharp threshold. This part of the talk is based on a joint work with Erlang Surya.

Dalhousie-AARMS AAMP Seminar: Erick Schulz (ETH Zürich)
2023-03-31 16:00 - 17:00 (America/Halifax) | Dalhousie University, Halifax, Nova Scotia, Canada
