Diversity in the Mathematical Sciences 2024
2024-07-29 - 2024-08-02 | Dalhousie University, Halifax, Nova Scotia, Canada
Objectives: The mathematical institutes in Canada have joined forces to offer annual summer schools geared toward women and underrepresented groups in mathematics and related sciences. The first school will be at Dalhousie University in Summer 2024.
The goals of the summer school are two-fold. First, to introduce students to research level mathematics and second, to encourage more female and female-identifying students to pursue graduate school in the mathematical sciences. The research theme of the 2024 summer school will be Combinatorial Commutative Algebra, as described below. By introducing the advanced mathematics in a supportive and engaging environment, we aim to give students the tools and the support structure that will enable them to thrive in graduate school.
Synopsis: The main tools to study zero sets of polynomials using algebraic tools come from Commutative Algebra. When the polynomials have only one term – monomials – one can use methods from combinatorics, topology, linear programing and more to study their algebraic properties. The development of such techniques, going back to the 1960’s and still a vibrant area of research today, is the focus of the field of Combinatorial Commutative Algebra.
Our school will introduce some of these ideas to the participants via concrete examples and problems. We will cover topics including: edge ideals of graphs, Hilbert functions, computational commutative algebra and discrete homotopy theory.
The school will also include panels, discussions of graduate school, academic and nonacademic jobs and issues facing women in mathematics in general. We will have morning lectures, afternoon tutorials and mini-topics.
We are seeking applications from female and female-identifying students who have finished at least two years of an undergraduate degree in the mathematical sciences.
Required background: Applicants having successfully completed a Honour’s-level proof-based course in linear algebra will be given full consideration. A third-year course in algebra covering rings and ideals will be considered an asset.
Applicants should submit transcripts, and arrange for a letter of recommendation addressing their potential to benefit from this school.
Funding: The Summer School will cover room and board as well as travel expenses for all participants.

Graph Searching in Canada Workshop 2024
2024-08-07 - 2024-08-09 | Dalhousie University, Halifax, Nova Scotia, Canada
The Graph Searching in Canada 2024 workshop will be held at Dalhousie University on August 7-9, 2024. The purpose of the workshop is to bring together researchers studying graph searching problems and their variants, such as as Cops and Robbers, Localization, searching, firefighting, burning, and eternal domination. Our plenary speakers will be Dr. Andrea Burgess (University of New Brunswick – Saint John) and Dr. Kerry Ojakian (Bronx Community College – CUNY).
In addition to the plenary talks, there will be contributed talks in the mornings, with the afternoons free for discussion, networking, and collaboration. A student workshop, aimed at graduate and senior undergraduate students, will be held on August 7th.

Atlantic Graph Theory Seminar
2024-09-18 15:30 - 16:30 UTC | Zoom seminar
Title: How do we use graphs to transmit quantum information?
Time: 3.30pm, Atlantic time, (1:30, CDT) Wednesday Sept. 18
Speaker: Hermie Monterde, University of Manitoba
Abstract:
In this talk, a graph $G$ represents a quantum spin network (a networking of interacting subatomic particles). The vertices and edges of $G$ represent the particles and their interactions in the network. Consider the complex unitary matrix $U(t)=exp(itA)$, where $A$ is the adjacency matrix of $G$, $i^2=-1$ and $t$ is a real number. The propagation of quantum states in the quantum system determined by $G$ is governed by the matrix $U(t)$. In particular, $|U(t)_{u,v}|^2$ may be interpreted as the probability that the quantum state assigned at vertex $u$ is transmitted to vertex $v$ at time $t$. In this talk, we give an overview of the study of quantum state transfer in graphs. We discuss old and new results in this area with emphasis on the concepts and techniques borrowed from graph theory and linear algebra.

Zoom link:
https://us02web.zoom.us/j/86861499971?pwd=[REDACTED]

Atlantic Graph Theory Seminar
2024-09-25 15:00 - 16:30 | Online via Zoom
Recolouring Graphs: Decompositions, A Dichotomy Theorem and Frozen Colourings
Speaker: Kathie Cameron, Wilfrid Laurier University
A k-colouring of a graph G is an assignment of at most k colours to the vertices of a graph so that the ends of each edge of the graph get different colours. We consider the question: When it is possible to obtain any k-colouring from any other by changing the colour of one vertex at a time, while always having a k-colouring? This question is equivalent to asking whether the “reconfiguration graph” is connected: The reconfiguration graph of the k-colourings, denoted Rk(G), is the graph whose vertices are the k-colourings of G, and two colourings are adjacent in Rk(G) if they differ in colour on exactly one vertex. We call a graph recolourable if Rk(G) is connected for every k greater than its chromatic number.

We have characterized the graphs H such that all graphs G which don’t contain H as an induced subgraph are recolourable. We have done the same when two 4-vertex graphs are excluded as induced subgraphs (except for one class) and for some classes of graphs which exclude as an induced subgraph the path on 5 vertices.

Decompositions are important in solving optimization problems on structured classes of graphs. We have shown that modular decomposition and a stronger version of clique cutsets which we call tight clique cutsets can be used to show that certain classes are recolourable.

A k-colouring of a graph is called frozen if there is no vertex whose colour can be changed so that the result is still a k-colouring. A frozen colouring corresponds to an isolated vertex of the reconfiguration graph, and thus the existence of a frozen colouring is one way to show that a class of graphs is not recolourable. We have found several new classes of graphs with frozen colourings and an operation which transforms a k-chromatic graph with a frozen (k+1)-colouring into a (k+1)-chromatic graph with a frozen (k+2)-colouring.
This is joint work with Manoj Belavadi, Elias Hildred, Owen Merkel and Dewi Sintiari.

Zoom link:
https://us02web.zoom.us/j/86861499971?pwd=[REDACTED]

Meeting ID: 868 6149 9971
Passcode: [REDACTED]

Atlantic Graph Theory Seminar
2024-10-02 15:30 - 16:30 | Online via Zoom
The Martin Invariant and Other Results on the Interlace Polynomials
Josephine Reynes, University of Waterloo
There are many well studied graph polynomials, but this talk will focus on the Martin polynomial and the interlace polynomial. Specifically, this talk will look at how these two polynomials are related and how results on the Martin polynomial can be extended to the interlace polynomial. The Martin invariant, a specific evaluation of the Martin polynomial, obeys the symmetries of the Feynman period. The Feynman period of a graph is useful in quantum field theory, but difficult to compute and thus there is interest in finding graph invariants that have the same symmetries. It was quickly established that the interlace polynomial on interlace graphs was equal to the Martin polynomial on the associated 4-regular graph. While only graphs not containing a set of forbidden vertex minors are interlace graphs, the interlace polynomial is defined over all graphs. We discuss how this provides a way to try and extend the notion of Feynman symmetries via the interlace polynomial and some specific classes of graphs with formulas. Additionally, the interlace polynomial is only equal to the Martin polynomial for interlace graphs of 4-regular graphs, but the Martin polynomial is defined for 2k-regular graphs. Thus, we work toward creating an interlace-like polynomial for graphs derived from 2k-regular cases of the Martin polynomial.
Zoom link:
https://us02web.zoom.us/j/86861499971?pwd=[REDACTED]
Meeting ID: 868 6149 9971
Passcode: [REDACTED]

2024 Science Atlantic Mathematics Statistics and Computer Science Undergraduate Student Conference
2024-10-04 - 2024-10-05 | Acadia University, Wolfville, Nova Scotia, Canada
The 2024 Science Atlantic Mathematics, and Computer Science Conference will take place at Acadia University during October 4-5, 2024. The conference will consist of a collection of invited plenary lectures, mathematics and computer science competitions and scientific research presentations by undergraduate students.
The conference is part of the larger annual Science Atlantic Mathematics, Statistics and Computer Science Conference series.
One overall aim of this exciting conference series is to bring together undergraduate students and faculty from universities based in Atlantic Canada. In doing so, the conference series promotes Scientific Discovery and literacy within the Mathematical, Statistical and Computing Sciences while at the same time fostering existing and promoting new collaborative and interdisciplinary activities amongst students and faculty.

Atlantic Graph Theory Seminar
2024-10-23 15:30 - 16:30 | Online via Zoom
Speaker #1: Peter Collier, Dalhousie University
Title #1: Zero Forcing on Twisted Hypercubes

Abstract #1:
The hypercube stands out as a compelling and versatile structure that extends the geometric notion of a cube into higher dimensions. We study the twisted hypercube variant in an attempt to optimize processes on similarly degree-regular, highly connected graphs. The particular process we optimize is zero forcing, a graph infection process in which a particular colour change rule is iteratively applied to the graph and an initial set of vertices. We use the alternative framing of forcing arc sets to construct a family of twisted hypercubes of dimension k$geq3$ with zero forcing sets of size $2^{k-1}-2^{k-3}+1$.

Speaker #2: Alexander Clow, Simon Fraser University
Title #2: Cornering Robots and Synchronizing Automata

Abstract #2:
A deterministic finite automata (DFA) is a model for any deterministic computational system with a finite number of states. In this talk, we describe a DFA as a finite directed multigraph G = (V, E), possibly with loops, along with an edge labelling ψ : E → Ψ. Here the vertices of the graph are the states the system might be in, the edge labels are possible inputs to the system, and the edges represent the transitions between states. Words σ generated from the alphabet Ψ act on vertices, v, as if v is the initial state of the system, and σ(v) is the state of the system after input σ is given. A word σ is synchronizing if for all u, v ∈ V , σ(u) = σ(v).
In this talk, we define a general strategy for constructing synchronizing words, which we call the cornering strategy. We then show that a DFA is synchronizable if and only if the cornering strategy can be successfully applied. As a demonstration of the strategy, we will discuss how all DFAs arising from movement in Rd can be synchronized. This is joint work with Peter Bradshaw (University of Illinois Urbana-Champaign) and Ladislav Stacho (Simon Fraser University).

Zoom link:
https://us02web.zoom.us/j/86861499971?pwd=[REDACTED]

Meeting ID: 868 6149 9971
Passcode: [REDACTED]

Atlantic Graph Theory Seminar
2024-10-30 15:30 - 16:30 | Online via Zoom
Some problems on graph sequences
David Galvin, University of Notre Dame

I’ll talk about some problems concerning unimodality (or otherwise) of some graph sequences that come from enumeration. The focus will be on the matching sequence, the independent set sequence and the domination sequence of a graph. As well as mentioning some recent work (with Ball, Hyry, Taylor and Weingartner, and with Zhang), I’ll describe some favorite open problems.

Zoom link:
https://us02web.zoom.us/j/86861499971?pwd=[REDACTED]

Meeting ID: 868 6149 9971
Passcode: [REDACTED]

Atlantic Graph Theory Seminar
2024-11-06 15:30 - 16:30 | Online via Zoom
On the two table case of the directed Oberwolfach problem
Speaker: Alice Lacaze-Masmonteil, University of Regina

A directed variant of the famous Oberwolfach problem, the directed Oberwolfach problem considers
the following scenario. Given n people seated at t round tables of size m1,m2 . . . ,mt , respectively,
such that m1+m2+· · ·+mt = n, does there exist a set of n−1 seating arrangements such
that each person is seated to the right of every other person precisely once? I will first demonstrate
how this problem can be formulated as a type of graph-theoretic problem known as a cycle decomposition
problem. Then, I will discuss a particular style of construction that was first introduced
by R. Häggkvist in 1985 to solve several cases of the original Oberwolfach problem. Lastly, I will
show how this approach can be adapted to the directed Oberwolfach problem, thereby allowing
us to obtain solutions for previously open cases. Certain results discussed in this talk arose from
collaboration with Daniel Horsley.

Zoom link:
https://us02web.zoom.us/j/86861499971?pwd=[REDACTED]

Meeting ID: 868 6149 9971
Passcode: [REDACTED]

Atlantic Graph Theory Seminar
2024-11-27 15:30 - 16:30 | Online via Zoom
Speaker: Iain Beaton, Acadia University
Title: Reconfiguring minimal dominating sets under a generalization of token sliding

Abstract:
A dominating set S in a graph is a subset of vertices such that every vertex is either in S or adjacent to a vertex in S. A minimal dominating set M is a dominating set such that M −v is not a dominating set for all v ∈ M. In this talk we introduce a reconfiguration graph R(G) for minimal dominating sets under a generalization of the token sliding model. We give some preliminary results which include showing that R(G) is connected for trees and split graphs. Additionally we classify all graphs which have complete or empty reconfiguration graphs.

Zoom link:
https://us02web.zoom.us/j/86861499971?pwd=[REDACTED]

Meeting ID: 868 6149 9971
Passcode: [REDACTED]

University of New Brunswick Data Challenge 2024
2024-11-29 | University of New Brunswick (Fredericton Campus), Fredericton, New Brunswick, Canada
The UNB Data Challenge 2024 will be the 9th iteration of the nationwide competition on Nov. 29, 2024, in a virtual format. Take up the challenge and demonstrate the power of data.
Participants and teams will be able to showcase their ability to tell a story driven by data in unique competitive formats. 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.

AARMS Doctoral Thesis Award Winner Seminar
2024-12-19 13:30 - 14:30 | Online via Zoom
A tangent category approach to operadic geometry

Marcello Lanfranchi
December 19, 2024 @ 1:30pm

Abstract:
A tangent category consists of a collection of abstract objects equipped with a structure, called a tangent structure, which makes those abstract objects into locally linear geometric spaces.
In my thesis, I introduced and studied a list of geometric theories from the perspective of tangent category theory. In particular, I showed that each (opposite) category of algebras, such as associative, commutative, or Lie algebras, comes equipped with a tangent structure which allows one to regard those algebraic objects as “operadic” affine schemes; I then extended some constructions of algebraic geometry to this context.
In this talk, I would like to introduce you to the wonderful world of tangent category theory, briefly recall the notion of an operad and its algebras, construct the algebraic and the geometric tangent categories of an operad, and, time permitting, briefly discuss some constructions such as vector fields, the slice tangent category, and differential bundles.
Part of the research for this project was done in collaboration with Sacha Ikonicoff (Université de Strasbourg) and Jean-Simon Pacaud Lemay (Macquarie University).
About the speaker:
Dr. Marcello Lanfranchi is one of the winners of this year’s AARMS Doctoral Thesis Award. He received his PhD from Dalhousie University in October 2024 under the supervision of Dr. Geoffrey Crutwell and Dr. Dorette Pronk for a thesis entitled “A tangent category approach to operadic geometry”.
Join Zoom Meeting
https://us02web.zoom.us/j/84617802983pwd=[REDACTED]
Meeting ID: 846 1780 2983
Passcode: [REDACTED]

Atlantic Graph Theory Seminar
2025-01-15 15:30 - 16:30 | Online via Zoom
Speakers: Prangya Parida, U. Ottawa, and Kiara McDonald, U. Victoria
Zoom link: https://us02web.zoom.us/j/86415230827?pwd=[REDACTED]

—————————————————
Prangya Parida:
Title: Cover-free families on graphs

Abstract: A family of subsets of a t-set is called a d-cover-free family if no subset is contained in the union of any d other subsets. We denote by t(d, n) the minimum t for which there exists a d-cover-free family of a t-set with n subsets. Cover-free families (CFF) have wide applications in combinatorial group testing, where a d-CFF(t, n) can be used to identify d defective items in a group of n items with t tests. It is well-known that t(1, n) can be obtained by applying the famous Sperner’s Theorem. For d geq 2, we rely on bounds for t(d, n). Erdös, Frankl, and Füredi provided bounds for t(2, n) using the probabilistic method, given by 3.106 log(n) < t(2, n) < 5.512 log(n). Using a derandomization technique, Porat and Rothschild presented a deterministic polynomial-time algorithm to construct d-CFFs that achieves t = O(d^2 log(n)). Some upper bounds on t(2, n) (in some cases exact bounds) for small values of n are provided by Li, van Rees, and Wei in 2006.
In this talk, we extend the definition of a cover-free family to include a graph G, which we denote as overline{G}-CFF, where the edges of the graph specify the pair of subsets whose union must not cover any other subset. We denote by t(G) the minimum t for which there exists a overline{G}-CFF. The traditional 2-CFF(t, n) is a special case of overline{G}-CFF when G is a complete graph of n vertices. This generalization of cover-free families provides a richer combinatorial structure that lies between being a 1-CFF and a 2-CFF.
We will discuss some classical results on cover-free families, along with general constructions of overline{G}-CFFs, as well as specific constructions for certain families of graphs. We prove that for a graph G with n vertices, t(1, n) leq t(G) leq t(2, n) and show that for an infinite family of Star graphs S_n with n vertices, t(S_n) = t(1, n). Interestingly, we also give a construction of CFFs on a Path (P_n) or Cycle (C_n) with n vertices using a mixed-radix Gray code. This yields an upper bound for t(P_n) and t(C_n) that is smaller than the lower bound of t(2, n) mentioned above.
This is joint work with Lucia Moura.

——————————————————
Kiara McDonald:
Title: Broadcast Independence in Trees

Abstract: In the area of Graph Theory, the well-known problems of domination, packing and independence are generalized by broadcast domination, broadcast packing and broadcast independence. As an analogy and application, consider a city, where one wants to place cell towers of different signal strengths subject to certain conditions. If every building in the city hears the signal from at least (respectively at most) one tower, then the broadcast is dominating (respectively packing). If no tower hears the signal from another tower, the broadcast is independent. The sum of the tower signal strengths is called the cost of the broadcast. The total cost of a maximum independent broadcast is called the broadcast independence number.
Our research was focused on determining explicit formulas and polynomial time algorithms for the broadcast independence number of various types of graphs. This parameter is difficult to compute for graphs in general, so we restrict the problem to specific classes of graphs to make use of their special structural properties to solve the problem. For a graph from a given class, we constructed a new graph, called the broadcast ball intersection graph. We were able to show that if the broadcast ball intersection graph is weakly chordal, then broadcast independence is polynomial time solvable for the given class of graphs. In this talk, we will focus on the broadcast ball intersection graph of trees. This talk is based on joint work with Richard Brewster (TRU) and Jing Huang (UVic).

Atlantic Graph Theory Seminar
2025-01-22 15:30 - 16:30 | Online via Zoom
Ramsey numbers of signed graphs
Ben Seamone, Dawson College and Université de Montréal

Abstract:
Nathan Acheampong (Université de Montréal) Francis Clavette (Université de Montréal)
Geˇna Hahn (Université de Montréal) Margaux Marseloo (Université Paris-Saclay) Viktor
Paardekooper (Université de Montréal), and Ben Seamone* (Dawson College & Université de Montréal)

A signed graph is a pair (G, σ) where G = (V,E) is a graph and σ : E(G) → {+, −} is
a signature which assigns a sign to each edge of G. One well-studied operation on signed
graphs is that of switching at a vertex v ∈ V (G), by which we mean that every edge incident
to v has its sign changed. Two signed graphs are called equivalent if one can be obtained
from the other by a sequence of vertex switches.

We call a complete signed graph positive (negative) if every edge is positive (negative). We
study the following Ramsey problem on signed graphs – for positive integers s and t, what
is the smallest n such that every signed complete graph on n vertices has an equivalent
signed complete graph containing either a negative Ks or positive Kt? This “signed Ramsey
number” is denoted r±(s, t). We show how a variety of approaches lead to upper and lower
bounds on r±(s, t), settle an open problem by establishing the exact value of r±(4, t) for
every t, and determine the asymptotics of r±(5, t) and r±(6, t).

Zoom link:
https://us02web.zoom.us/j/86861499971?pwd=[REDACTED]

Meeting ID: 868 6149 9971
Passcode: [REDACTED]

Combinatorial Algebra meets Algebraic Combinatorics 22nd annual workshop
2025-01-24 - 2025-01-26 | York University, 4700 Keele Street, Toronto, Ontario, M3J 1P3, Canada
The Combinatorial Algebra meets Algebraic Combinatorics (CAAC) workshop is an annual meeting taking place in Canada since 2004, with a focus on the continuously evolving interactions between combinatorial algebra and algebraic combinatorics. These meetings provide a strong connection between the two communities and help with the development of these fields. Historically, the CAAC meetings provided opportunities for graduate students, postdoctoral fellows, and early career researchers to present their work, learn about new research directions in related fields, and establish future collaborations. The 22nd Annual CAAC conference will take place at the York University from Friday, January 24, 2025, to Sunday, January 26, 2025. CAAC 2025 will include four invited 50-minute lectures, a collection of contributed talks given by graduate students and postdoctoral fellows, a poster session, and time for informal social and scientific interactions.

Atlantic Graph Theory Seminar
2025-01-29 15:30 - 16:30 | Online via Zoom
Switching m-edge coloured graphs
Speaker: Gary MacGillivray, University of Victoria

Abstract:

An m-edge-coloured graph consists of a set of vertices, any two of which are either joined by an edge of one of m colours or not joined at all. The operation of switching at a vertex v of an m-edge-coloured graph with respect to an element of a subgroup Gamma of S_m permutes the colours of the edges incident with v. Switching defines an equivalence relation on the set of all m-edge-coloured graphs; G and H are Gamma-switch-equivalent if there exists a sequence of switches that transform G into H.
We consider the following problems and their solutions. For a fixed subgroup Gamma of S_m:
1) determine the number of equivalence classes of k-vertex m-edge-coloured graphs under switching with respect to Gamma.
2) how hard is it to determine whether given m-edge-coloured graphs G and H are Gamma-switch equivalent?
3) for a fixed m-edge-coloured graph H, how hard is it to determine whether a given m-edge-coloured graph G can be switched with respect to Gamma so that there is a homomorphism of the transformed m-edge-coloured graph to H? (A homomorphism is a mapping of V(G) to V(H) that preserves edges and colours.)
We will also discuss extending these results to (m,n)-mixed graphs. These have m different colours of edges and n different colours of arcs.

Zoom link:
https://us02web.zoom.us/j/86861499971?pwd=[REDACTED]

Meeting ID: 868 6149 9971
Passcode: [REDACTED]

CRG Seminar: Modelling Fish Stock Biomass Dynamics in a Multi-gear Fishery and Determining the Stock Status
2025-01-31 12:00 - 13:00 | online via webex
Abstract: A marine fishery is an important sector in many countries as it contributes towards the nutritional requirements of people and provides income and employment to the associated population. Compared to other natural resources fish being a living resource has the capacity for rebuilding through reproduction. Sustainable management of the marine fishery resources is very important to avoid resource depletion as well as collapse. Biomass of individual species needs to be estimated and its dynamics have to be studied regularly for determining vital reference points such as maximum sustainable yield and its use for sustainable management of the fish stocks. An important model used for studying the biomass dynamics of marine fish stocks is the biomass dynamics model and its modified versions. The necessary information required for such study is time series data on fish catch and fishing effort in terms of number of hours of fishing. Most of the fisheries are of multi-species and multi-gear nature with each fishing gear targeting more than one fish species. Hence biomass dynamics models admitting multi-gear type of harvest are most suited for marine fishery management. Annual fish catch along with fishing effort of a group of fishing gears contributing to the catch are simultaneously used in these models to estimate biomass and other model parameters to make conclusions for fisheries management. One of these models applied to the marine fish stocks in India is the focus of this presentation.
Webex Link:
Join from the meeting link
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Join by meeting number
Meeting number (access code): 2773 424 0869
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Atlantic Graph Theory Seminar
2025-02-05 15:30 - 16:30 | Online via Zoom
Kemeny’s constant for Markov chains and random walks on graphs
Speaker: Jane Breen, Ontario Tech University

Kemeny’s constant is an interesting and useful quantifier of how well-connected the states of a Markov chain are. Though it was first introduced in the 1960s, interest in this concept has recently exploded. This talk will provide an introduction to Markov chains, an overview of the history of Kemeny’s constant, discussion of some applications, and a survey of recent results, with an emphasis on those where the combinatorial structure of the Markov chain is of interest. This comes to the forefront when the Markov chain in question is a random walk on a graph, in which case Kemeny’s constant is interpreted as a measure of how `well-connected’ the graph is.

Zoom link:
https://us02web.zoom.us/j/86861499971?pwd=[REDACTED]

Meeting ID: 868 6149 9971
Passcode: [REDACTED]

Atlantic Graph Theory Seminar
2025-02-12 15:30 - 16:30 | Online via Zoom
Time: 3:30 pm, Atlantic time, (4:00 pm NST) Wednesday, Feb. 12
Speaker: Robert Bailey, Memorial University
Title: Computer constructions of distance-regular graphs with primitive automorphism groups

Abstract:
A graph is distance-regular if, for each vertex $v$ and each vertex $w$ at distance $i$ from $v$, the number of neighbours of $w$ at distances $i-1$, $i$ or $i+1$ from $v$ depends only on $i$, and not on the choice of $v$ or $w$. These are highly-structured graphs with interesting structural and algebraic properties. Many of the well-known examples have large symmetry groups.

The GAP computer algebra system contains libraries of primitive permutation groups (i.e. those which preserve no interesting equivalence relations). With the assistance of my undergraduate research students, I have been analyzing these libraries with the ultimate aim of classifying the distance-regular graphs with such groups as automorphism groups. In this talk, I will discuss the status of this work, a few surprises which came up along the way, and some (theoretical and computational) questions which remain open.

Zoom link:
https://us02web.zoom.us/j/86861499971?pwd=[REDACTED]

Meeting ID: 868 6149 9971
Passcode: [REDACTED]

Girls STEM Up Conference 2025: connect and Conquer
2025-02-15 | Delta Hotels by Mariott Fredericton, 225 Woodstock Rd, Fredericton, New Brunswick, Canada
Girls STEM Up is collectively 28 women students based in Fredericton, NB, who are passionate about bridging the gap of gender inequity in STEM fields, focusing on intersectionality. Founded in 2019, with the goal of sparking necessary discussions and changing the perception of women in STEM. We have since expanded to include 60+ general members, high school ambassadors, and volunteers.
Our experiences as underrepresented individuals in STEM have brought us together to promote diversity, inclusion, and equity in these fields through representation, awareness, and education.
We proudly host an annual conference celebrating girls’ and women in STEM’s achievements. Our event provides an extraordinary platform for women and girls to connect with like-minded individuals, exchange valuable knowledge, and shine spotlight to incredible success stories in STEM. This ignites passion in those pursuing STEM careers. Our sixth edition of the conference GSU: Connect and Conquer will take place in February 2025.

2025 Integration Competition
2025-02-26 | Saint Francis Xavier University, 4130 University Avenue, Antigonish, Nova Scotia, B2G 2W5, Canada
The Integration Competition is a fun, head-to-head competition among first-year calculus students to solve integrals, with the winners of each matchup progressing to further rounds until a winner emerges. Participants challenge themselves to solve integral problems on-the-spot, and in addition to generating interest and excitement in mastering this mathematical skill, the event is used to promote mathematics more broadly to potential majors.

Atlantic Graph Theory Seminar
2025-02-26 15:30 - 16:30 | Online via Zoom
Speaker: Karen Meagher, University of Regina
Title: Derangement graphs and the intersection density of permutation groups

Abstract:
Two permutations are intersecting if they both map some $i$ to the same point, equivalently, permutations $sigma$
and $pi$ are intersecting if and only if $pi^{-1}sigma$ has a fixed point. A set of permutations is called intersecting if any two permutations in the set are intersecting. For any transitive group the stabilizer of a point is an intersecting set. The intersection density of a permutation group is the ratio of the size of the largest intersecting set in the group, to the size of the stabilizer of a point. If the intersection density of a group is 1, then the stabilizer of a point is an intersecting set of maximum size. Such groups are said to have the ErdH{o}s-Ko-Rado property.

One effective way to determine the intersection density of a group is build a graph whose vertices are the elements of the group and the edges are defined so that the cocliques (or the independent sets) in the graph are exactly the intersecting sets in the group. This graph is called the derangement graph for the group. The focus on this talk is to demonstrate several ways we can use the derangement graph to find the intersection density of a group.

An easy example of how this can be done is if the graph has a clique with the size of the degree of the group, then the group has intersection density 1. We can also use graph homomorphisms to find bounds on the intersection density. For many small groups, the derangement graph has a very simple form and the intersection density of the group can be easily found simply from the structure of the derangement graph. In a surprising number of cases, eigenvalues of the derangement graph can be found using the representation theory of the group and, using tools from algebraic graph theory, these eigenvalues can be used to bound the size of a coclique.

Zoom link:
https://us02web.zoom.us/j/86861499971?pwd=[REDACTED]

Meeting ID: 868 6149 9971
Passcode: [REDACTED]

Atlantic Canada Data Science Tour
2025-03-07 12:00 - 13:00 | Online via Zoom
A Hybrid Seminar Series for University Students in Statistics or Computer Science
“Mediation Analysis of Recurrent Events”
Guest Speaker: Shenita Pramij (Memorial University)
DATE: Friday, March 7, 2025
TIME: 12:00–1:00 p.m., Atlantic time
LOCATION: Online via Zoom
This hybrid series for students in statistics and computer science programs features faculty members and students from universities in Atlantic Canada talking about their work and career paths in statistical sciences. The guest speaker for this online presentation will be Shenita Pramij.
Shenita is a PhD student in Statistics at Memorial University of Newfoundland. Her research focuses on mediation analysis, and she has broad interests in modelling complex processes with applications in healthcare and public policy. She also has extensive experience in the public sector as a compliance researcher. Her work aims to enhance decision-making in public policy and inform targeted interventions.
PRESENTATION ABSTRACT : Inferring the direct effects of exposure in recurrent event processes, while accounting for mediating factors, is crucial, yet conventional approaches face significant limitations in the presence of complex causal relationships. We introduce two methods to address these challenges. We first explore a two-stage sequential G-estimation method to estimate the controlled direct effect of a randomly assigned exposure, while accounting for potential mediators and confounders, using intensity-based models of recurrent event processes. We also introduce a novel one-stage estimation method based on the estimating equations framework, leveraging the sequential G-estimation principle. We demonstrate that both methods yield unbiased controlled direct effect estimates. The one-stage method also enables the analytical derivation of an estimator for the standard error of the direct effect estimator. We illustrate our approach using a hospital readmission dataset of colorectal cancer patients to estimate the controlled direct effect of sex differences on hospital readmission.
We invite you to join us online! (We’ll send you the Zoom link when you register.)
GET THE DETAILS AND REGISTER HERE

Atlantic Graph Theory Seminar
2025-03-12 15:30 - 16:30 | Online via Zoom
Time: 3:30 pm, Atlantic time, (2:30 pm EST) Wednesday, Mar. 12
Speaker: Ron Gould, Emory University
Title: Looking for Saturation in all Kinds of Places

Abstract:
Given a graph $H$, a graph $G$ is $H$-saturated if $G$ does not contain $H$ as a subgraph, but the addition of any missing edge to $G$ results in a graph containing $H$ as a subgraph. An $H$-saturated graph with the maximum number of edges is called an extremal graph for $H$ and for a given order $n$ we denoted this as $ext(n, H).$ This is the well-known extremal number (or Turan number) of $H$ and is a well studied notion with a deep and beautiful history.

However, the focus of this talk will be the many other saturation questions that can be asked. These include what is the minimum number of edges in an $H$-saturated graph? What sizes (i.e. $|E(G)|$), other than the minimum or maximum, also allow $H$-saturated graphs on $n$ vertices? Is it possible to order the inclusion of the missing edges so that at each stage more copies of $H$ will be included? What about saturation in other settings such as in hypergraphs, edge-colored graphs, random graphs, or within graphs other than the complete graph?

Keywords: saturation, saturation spectrum, weak saturation

Zoom link:
https://us02web.zoom.us/j/86861499971?pwd=[REDACTED]

Meeting ID: 868 6149 9971
Passcode: [REDACTED]

Integration Tournament for UPEI students 2025
2025-03-14 | University of Prince Edward Island, Charlottetown, Prince Edward Island, Canada
Competition among UPEI Calculus Students to evaluate integrals the fastest.

Atlantic Graph Theory Seminar
2025-03-19 15:30 - 16:30 | Online via Zoom
The 2-burning number of a graph
Speaker: Ann Trenk, Wellesley College

Abstract:
We discuss a discrete-time model for the spread of information in a graph, motivated by the idea that people believe a story when they learn of it from two different origins. Similar to the burning number, in this problem, information spreads in rounds and a new source can appear in each round. For a graph $G$, we are interested in $b_2(G)$, the minimum number of rounds until the information has spread to all vertices of graph $G$. We are also interested in finding $t_2(G)$, the minimum number of sources necessary so that the information spreads to all vertices of $G$ in $b_2(G)$ rounds. In addition to discussing general results, we find $b_2(G)$ and $t_2(G)$ for the classes of spiders and wheels and show that their behavior differs with respect to these two parameters.

This is joint work with Catherine Jacobs (Wellesley College) and Margaret-Ellen Messinger (Mount Allison University).

Zoom link:
https://us02web.zoom.us/j/86861499971?pwd=[REDACTED]

Meeting ID: 868 6149 9971
Passcode: [REDACTED]

Mini course "Vertex operator algebras and their representations"
2025-03-24 - 2025-03-28 | Memorial University (St. John’s Campus), St. John's, Newfoundland and Labrador, Canada
Vertex operator algebras have been a topic of interest in mathematical physics for several decades, as they constitute one possible approach to formalize physical concepts from conformal field theory. They have relations to several other areas of mathematics, most notably to the theory of finite simple groups. This specific relation lead in fact to the award of the Fields Medal to Professor Richard Borcherds at the International Congress of Mathematicians in Berlin in 1998. Professor Gannon is the author of a well-known monograph on this topic.
The minicourse will consist of five lectures of 90 minutes each. The lectures will be aimed at students, primarily at the graduate level. We hope to attract about 20 participants from Memorial University, Atlantic Canada, and other parts of Canada, and possibly some international participants.

Atlantic Graph Theory Seminar
2025-03-26 15:30 - 16:30 | Online via Zoom
The Burning Number of Large Caterpillars
Danielle Cox, Mount Saint Vincent University
Abstract:
In this talk we will look at the history of the graph burning conjecture and the state of the art. We will also prove the conjecture for sufficiently large p-caterpillars. This is joint work with Kerry Ojakian (CUNY) and Margaret-Ellen Messinger (Mt Allison).

Zoom link:
https://us02web.zoom.us/j/86861499971?pwd=[REDACTED]

Meeting ID: 868 6149 9971
Passcode: [REDACTED]

Atlantic Canada AI Summit 2025
2025-05-01 - 2025-05-03 | St. Mary’s University, 923 Robie Street, Halifax, Nova Scotia, B3H 3C3, Canada
The Summit will showcase cutting-edge AI research, facilitate industry-academia collaboration, and highlight exceptional AI talents in the Atlantic region.

20th CMS-UPEI-AARMS Regional Math Camp
2025-05-02 - 2025-05-04 | University of Prince Edward Island, Charlottetown, Prince Edward Island, Canada
For more than 20 years, the School of Mathematical and Computational Sciences (SMCS), UPEI has hosted a Math Camp for students in grades 10 and 11 from PEI high schools. The Math Camp is the SMCS’s primary outreach effort. Its goals are to give some of PEI’s best students an opportunity to broaden their mathematical horizons beyond what they see in their course work, and to encourage them to continue their math studies at university.
