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X-ORIGINAL-URL:https://aarms.math.ca
X-WR-CALDESC:Events for 
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BEGIN:VTIMEZONE
TZID:UTC
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TZOFFSETTO:+0000
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DTSTART:20230101T000000
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BEGIN:VEVENT
DTSTART;TZID=UTC:20260304T153000
DTEND;TZID=UTC:20260304T163000
DTSTAMP:20260610T162222
CREATED:20260301T133901Z
LAST-MODIFIED:20260301T133901Z
UID:8564-1772638200-1772641800@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar
DESCRIPTION:Speaker: Andrea Burgess\, University of New Brunswick\nTitle: Colourings of combinatorial designs\n\nAbstract: A combinatorial design is a pair $(V\,\mathcal{B})$ where $V$ is a nonempty set of points\, and $\mathcal{B}$ is a collection of subsets of $\mathcal{B}$\, called blocks.  A $c$-colouring of a design $(V\,\mathcal{B})$ is a function $f:V \rightarrow C$\, where $C$ is a set of $c$ colours\, such that each block contains at least two points of different colours.  The design’s chromatic number is the least value of $c$ for which it admits a $c$-colouring.  While colourings of balanced incomplete block designs and cycle systems have been extensively studied\, relatively little is known regarding colourings of designs with restricted structural properties\, such as resolvability\, or colourings of certain other classes of designs\, such as group divisible designs.  In this talk\, we aim to bridge this gap.\n\nWe start by considering colourings of Kirkman triple systems (KTS)\, which are resolvable Steiner triple systems.  We show that there is a $3$-chromatic KTS$(v)$ if and only if $v \equiv 3$~(mod~$6$)\, and construct infinite families of $c$-chromatic KTS$(v)$ for every integer $c \geq 4$.\n\nWe then extend the study of colourings to group divisible designs (GDDs).  In a GDD\, the points are partitioned into groups; no block contains more than one point from any group\, but each pair of points not in the same group appears in exactly $\lambda$ blocks.  We consider the existence of uniform GDDs with arbitrary group size and arbitrary chromatic number $c$\, and further discuss colourings of GDDs with additional restrictions on the colours appearing in each group.\n\nIf time permits\, we will mention some results on equitable colourings of group divisible designs and packing designs; in this type of colouring\, each colour must appear an equal number of times (or as closely as possible) in each block.\n\nThis talk contains joint work with Nicholas Cavenagh\, Peter Danziger\, Diane Donovan\, Tara Kemp\, James Lefevre\, David Pike and E. \c{S}ule Yaz{\i}c{\i}.\n\n\nZoom link:\nhttps://us02web.zoom.us/j/88013261876?pwd=XGocyHqvseXY8metPztPoSuulEEejX.1\n\nMeeting ID: 880 1326 1876\nPasscode: 357963
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-39/
LOCATION:Online via Zoom
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="jeannette Janssen":MAILTO:jeannette.janssen@dal.ca
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20260211T153000
DTEND;TZID=UTC:20260211T163000
DTSTAMP:20260610T162222
CREATED:20260207T121840Z
LAST-MODIFIED:20260207T121840Z
UID:8545-1770823800-1770827400@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar
DESCRIPTION:Date and Time: Wednesday\, February 11\, 3.40 pm Atlantic time\nSpeaker: JD Nir\, Oakland University\nTitle: The Second Common Neighbourhood Conjecture\n\nAbstract: The Second Common Neighbourhood Conjecture is a question about the structure of shared neighbours in a graph. At first glance\, it seems like a nice problem for a new researcher to study: it requires only a basic understanding of graph theory to state\, examples are easy to understand\, and one can quickly prove the conjecture holds in certain cases. However\, the full conjecture remains stubbornly unsolved. If true\, the conjecture immediately improves the best known bound in a problem in enumerative graph theory. We will introduce the conjecture\, look at some of the cases where it is known to hold\, and explore the related enumeration question.\n\nZoom link:\nhttps://us02web.zoom.us/j/88013261876?pwd=XGocyHqvseXY8metPztPoSuulEEejX.1\n\nMeeting ID: 880 1326 1876\nPasscode: 357963
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-37/
LOCATION:Online via Zoom
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="jeannette Janssen":MAILTO:jeannette.janssen@dal.ca
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20260204T153000
DTEND;TZID=UTC:20260204T163000
DTSTAMP:20260610T162222
CREATED:20260130T184215Z
LAST-MODIFIED:20260130T184215Z
UID:8497-1770219000-1770222600@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar: Jorik Jooken - Feb 4
DESCRIPTION:Speaker: Jorik Jooken\, KU Leuven Kulak\nTitle: On vertex-girth-regular graphs: (Non-)existence\, bounds and enumeration\n\nAbstract: A vertex-girth-regular vgr(v\,k\,g\,lambda)-graph is a k-regular graph of girth g and order v in which every vertex belongs to exactly lambda cycles of length g. While all vertex-transitive graphs are necessarily vertex-girth-regular\, the majority of vertex-girth-regular graphs are not vertex-transitive. Similarly\, while many of the smallest k-regular graphs of girth g\, the so-called (k\,g)-cages\, are vertex-girth-regular\, infinitely many vertex-girth-regular graphs of degree k and girth g exist for many pairs k\, g. Due to these connections\, the study of vertex-girth-regular graphs promises insights into the relations between the classes of extremal\, highly symmetric\, and locally regular graphs of given degree and girth. This paper lays the foundation to such study by investigating the fundamental properties of vgr(v\,k\,g\,lambda)-graphs\, specifically the relations necessarily satisfied by the parameters  and to admit the existence of a corresponding vertex-girth-regular graph\, by presenting constructions of infinite families of vgr(v\,k\,g\,lambda)-graphs\, and by establishing lower bounds on the number v of vertices in a vgr(v\,k\,g\,lambda)-graph. It also includes computational results determining the orders of smallest cubic and quartic graphs of small girths.\nFull paper: https://www.combinatorics.org/ojs/index.php/eljc/article/view/v32i4p51\n\nZoom link:\nhttps://us02web.zoom.us/j/88013261876?pwd=XGocyHqvseXY8metPztPoSuulEEejX.1\n\nMeeting ID: 880 1326 1876\nPasscode: 357963
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-jorik-jooken-feb-4/
LOCATION:Online via Zoom
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="jeannette Janssen":MAILTO:jeannette.janssen@dal.ca
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20260121T153000
DTEND;TZID=UTC:20260121T163000
DTSTAMP:20260610T162222
CREATED:20260119T195230Z
LAST-MODIFIED:20260119T195230Z
UID:8488-1769009400-1769013000@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar
DESCRIPTION:Speaker: Shahriyar Pourakbar Saffar\, Memorial University of Newfoundland\nTitle: Existence of uniquely 2-colourable 4-cycle decompositions: A constructive proof\n\nAbstract: A cycle system of order $n$ is a decomposition of the edges of the complete graph $K_n$ into cycles of a fixed length. A cycle system is said to be $k$-colourable if we can assign $k$ colours to its vertices so that no cycle is monochromatic. If a cycle system is $k$-colourable but not $(k-1)$-colourable\, it is called $k$-chromatic. A $k$-colourable cycle system is uniquely $k$-colourable if its colouring is unique up to the permutation of colour classes.\n\nThe study of colouring cycle systems has been explored in various settings. In particular\, Horsley and Pike have examined the existence of $k$-chromatic $m$-cycle systems for any integers $m>2$ and $k>1$. While Forbes has investigated $3$-cycle systems with unique $3$-colourability\, the existence of uniquely $k$-colourable $m$-cycle systems in general remains an open problem.\n\nIn this talk\, we mainly focus on the construction of an infinite family of uniquely $2$-colourable $4$-cycle systems and also a uniquely $2$-colourable $4$-cycle decomposition of $K_n – I$\, for infinitely many integers $n \geq 2$. These constructions contribute to the broader study of uniquely colourable cycle systems and open new directions for future research.\n\n\nZoom link:\nhttps://us02web.zoom.us/j/88013261876?pwd=XGocyHqvseXY8metPztPoSuulEEejX.1\n\nMeeting ID: 880 1326 1876\nPasscode: 357963
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-36/
LOCATION:Online via Zoom
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="jeannette Janssen":MAILTO:jeannette.janssen@dal.ca
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20260114T153000
DTEND;TZID=UTC:20260114T163000
DTSTAMP:20260610T162222
CREATED:20260109T110348Z
LAST-MODIFIED:20260109T110348Z
UID:8481-1768404600-1768408200@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar
DESCRIPTION:Colourings of Balanced Incomplete Block Designs That Are Almost Locally Equitable \nDate and Time: Wednesday\, January 14\, 3.40 pm Atlantic time\nSpeaker: William Kellough\, Memorial University of Newfoundland \nAbstract: In this talk\, we study $\ell$-colourings of $(v\,k\,\lambda)$-BIBDs where within each block\, one colour is absent and the rest appear exactly $\frac{k}{\ell-1}$ times. We give necessary conditions for such colourings to exist. We show how Hadamard matrices\, affine planes\, and twin prime powers can be used to construct such coloured BIBDs. \nZoom link:\nhttps://us02web.zoom.us/j/88013261876?pwd=XGocyHqvseXY8metPztPoSuulEEejX.1 \nMeeting ID: 880 1326 1876\nPasscode: 357963
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-35/
LOCATION:Online via Zoom
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="jeannette Janssen":MAILTO:jeannette.janssen@dal.ca
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20251126T153000
DTEND;TZID=UTC:20251126T163000
DTSTAMP:20260610T162222
CREATED:20251123T124712Z
LAST-MODIFIED:20251123T124741Z
UID:8438-1764171000-1764174600@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar
DESCRIPTION:Date and Time: Wednesday\, November 26\, 3.40 pm Atlantic time\nSpeaker: Himanshu Gupta\, University of Regina\nTitle: On the eigenvalues of the graphs D(5\, q)\n\n\nAbstract: In 1995\, Lazebnik and Ustimenko introduced the family of q-regular graphs D(k\, q)\, which is defined for any positive integer k and prime power q. The connected components of the graph D(k\, q) have provided the bestknown general lower bound on the size of a graph for any given order and girth to this day. Furthermore\, Ustimenko conjectured that the second largest eigenvalue of D(k\, q) is always less than or equal to 2√q\, indicating that the graphs D(k\, q) are almost Ramanujan graphs. In this talk\, we will discuss some recent progress on this conjecture. This includes the result that the second largest eigenvalue of D(5\, q) is less than or equal to 2√q when q is an odd prime power.\n\nThis is joint work with Vladislav Taranchuk.\n\n\nZoom link:\nhttps://us02web.zoom.us/j/88013261876?pwd=XGocyHqvseXY8metPztPoSuulEEejX.1\n\nMeeting ID: 880 1326 1876\nPasscode: 357963
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-34/
LOCATION:Online via Zoom
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="jeannette Janssen":MAILTO:jeannette.janssen@dal.ca
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20251119T153000
DTEND;TZID=UTC:20251119T163000
DTSTAMP:20260610T162222
CREATED:20251112T211938Z
LAST-MODIFIED:20251112T211938Z
UID:8423-1763566200-1763569800@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar
DESCRIPTION:Date and Time: Wednesday\, November 19\, 3.40 pm Atlantic time\nSpeaker: Rachel Kirsch\, George Mason University\nTitle: Maximizing subgraph density by double counting\n\nAbstract: This talk will highlight the use of the method of counting in two ways in recent research on maximizing subgraph density in graphs of bounded degree and clique number.\n\nZoom link:\nhttps://us02web.zoom.us/j/88013261876?pwd=XGocyHqvseXY8metPztPoSuulEEejX.1\n\nMeeting ID: 880 1326 1876\nPasscode: 357963
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-33/
LOCATION:Online via Zoom
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="jeannette Janssen":MAILTO:jeannette.janssen@dal.ca
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20251105T153000
DTEND;TZID=UTC:20251105T170000
DTSTAMP:20260610T162222
CREATED:20251031T101807Z
LAST-MODIFIED:20251031T101807Z
UID:8357-1762356600-1762362000@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar
DESCRIPTION:Date and Time: Wednesday\, November 5\, 3.40 pm Atlantic time\nSpeaker: Kalina Petrova\, Institute of Science and Technology Austria\nTitle: Cameron’s conjecture on random Latin squares\n\nAbstract: A conjecture of Cameron states that the distribution of the number of odd rows in an n x n uniformly random Latin square is approximately binomial with n trials and success probability 1/2. We prove this conjecture in several different senses\, including total variation convergence\, a local central limit theorem\, and a large deviation principle. In fact\, we prove a generalisation for the joint distribution of the number of odd rows\, odd columns and odd symbols\, showing they behave roughly as independent binomials. Along the way\, we introduce several general techniques for the study of random Latin squares\, including a new re-randomisation technique via “stable intercalate switchings”\, and a new approximation theorem comparing random Latin squares with a certain independent model.\nThis is joint work with Matthew Kwan and Mehtaab Sawhney.\n\nZoom link:\nhttps://us02web.zoom.us/j/88013261876?pwd=XGocyHqvseXY8metPztPoSuulEEejX.1 \nMeeting ID: 880 1326 1876\nPasscode: 357963
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-32/
LOCATION:Online via Zoom
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="jeannette Janssen":MAILTO:jeannette.janssen@dal.ca
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20251029T153000
DTEND;TZID=UTC:20251029T163000
DTSTAMP:20260610T162222
CREATED:20251024T165928Z
LAST-MODIFIED:20251024T165928Z
UID:8344-1761751800-1761755400@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar:  Ben Moore - Oct 29
DESCRIPTION:Date and Time: Wednesday\, October 29\, 3.40 pm Atlantic time \nSpeaker: Ben Moore\, University of Manitoba \nTitle: Smoothed analysis for graph isomorphism \nAbstract: I’ll describe a simple algorithm which shows the following: Given any graph G\, add or remove edges uniformly at random with probability 100/v(G) to create a graph G’. We can test in polynomial time if G’ is isomorphic to any other graph H. In other words\, graph isomorphism is in P if you add a little bit of randomness to the instance. \nJoint work with: Michael Anastos and Matthew Kwan. \n\nZoom link: \nhttps://us02web.zoom.us/j/88013261876?pwd=XGocyHqvseXY8metPztPoSuulEEejX.1 \nMeeting ID: 880 1326 1876\nPasscode: 357963
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-ben-moore-oct-29/
LOCATION:Online via Zoom
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="jeannette Janssen":MAILTO:jeannette.janssen@dal.ca
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20251022T153000
DTEND;TZID=UTC:20251022T163000
DTSTAMP:20260610T162222
CREATED:20251017T111210Z
LAST-MODIFIED:20251017T111210Z
UID:8339-1761147000-1761150600@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar
DESCRIPTION:Date and Time: Wednesday\, October 22\, 3.40 pm Atlantic time\nSpeaker: Theodore (Teddy) Mishura\, Toronto Metropolitan University\nTitle: Liminal burning the hypercube\n \nAbstract: Liminal burning generalizes both the burning and cooling processes in graphs. In $k$-liminal burning\, a Saboteur reveals $k$-sets of vertices in each round\, and the Arsonist must choose sources only within these sets. The result is a two-player game with the corresponding optimization parameter $b_k$ called the $k$-liminal burning number. For $k = |V (G)|$\, liminal burning is identical to burning\, and for $k = 1$\, liminal burning is identical to cooling. Here\, we study the behavior of $k$-liminal burning on the hypercube graph $Q_n$ and note that finding the $k$-liminal burning number of $Q_n$ is strongly related to finding an appropriate Sperner family—a family of sets where no element is a proper subset of another. We introduce a variant of these Sperner families that\, alongside other methods\, allows us to establish bounds on $b_k(Q_n)$ for various values of $k$. We also determine the exact cooling number of the $n$-dimensional hypercube to be $n.$\n\nJoint work with: Anthony Bonato\, Trent Marbach\, John Marcoux\n\nZoom link:\nhttps://us02web.zoom.us/j/88013261876?pwd=XGocyHqvseXY8metPztPoSuulEEejX.1 \nMeeting ID: 880 1326 1876\nPasscode: 357963
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-31/
LOCATION:Online via Zoom
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="jeannette Janssen":MAILTO:jeannette.janssen@dal.ca
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20250326T153000
DTEND;TZID=UTC:20250326T163000
DTSTAMP:20260610T162222
CREATED:20250319T205857Z
LAST-MODIFIED:20250319T205857Z
UID:8166-1743003000-1743006600@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar
DESCRIPTION:The Burning Number of Large Caterpillars \nDanielle Cox\, Mount Saint Vincent University \nAbstract:\nIn 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).\n\nZoom link:\nhttps://us02web.zoom.us/j/86861499971?pwd=rTDAaju0TCu24asnaBGvkuNlT11KZ1.1\n\nMeeting ID: 868 6149 9971\nPasscode: 325258
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-30/
LOCATION:Online via Zoom
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="jeannette Janssen":MAILTO:jeannette.janssen@dal.ca
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20250319T153000
DTEND;TZID=UTC:20250319T163000
DTSTAMP:20260610T162222
CREATED:20250313T101400Z
LAST-MODIFIED:20250313T101400Z
UID:8039-1742398200-1742401800@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar
DESCRIPTION:The 2-burning number of a graph\nSpeaker: Ann Trenk\, Wellesley College\n\nAbstract:\nWe 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.\n\nThis is joint work with Catherine Jacobs (Wellesley College) and Margaret-Ellen Messinger (Mount Allison University).\n \nZoom link:\nhttps://us02web.zoom.us/j/86861499971?pwd=rTDAaju0TCu24asnaBGvkuNlT11KZ1.1\n\nMeeting ID: 868 6149 9971\nPasscode: 325258
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-29/
LOCATION:Online via Zoom
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="jeannette Janssen":MAILTO:jeannette.janssen@dal.ca
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20250312T153000
DTEND;TZID=UTC:20250312T163000
DTSTAMP:20260610T162222
CREATED:20250305T143502Z
LAST-MODIFIED:20250305T143502Z
UID:7955-1741793400-1741797000@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar
DESCRIPTION:Time: 3:30 pm\, Atlantic time\, (2:30 pm EST) Wednesday\, Mar. 12\nSpeaker: Ron Gould\, Emory University\nTitle: Looking for Saturation in all Kinds of Places\n\nAbstract:\nGiven 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.\n\nHowever\, 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?\n\nKeywords: saturation\, saturation spectrum\, weak saturation\n \nZoom link:\nhttps://us02web.zoom.us/j/86861499971?pwd=rTDAaju0TCu24asnaBGvkuNlT11KZ1.1\n\n\nMeeting ID: 868 6149 9971\nPasscode: 325258
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-28/
LOCATION:Online via Zoom
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="jeannette Janssen":MAILTO:jeannette.janssen@dal.ca
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20250226T153000
DTEND;TZID=UTC:20250226T163000
DTSTAMP:20260610T162222
CREATED:20250220T195135Z
LAST-MODIFIED:20250220T195135Z
UID:7949-1740583800-1740587400@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar
DESCRIPTION:Speaker: Karen Meagher\, University of Regina\nTitle: Derangement graphs and the intersection density of permutation groups\n\nAbstract:\nTwo permutations are intersecting if they both map some $i$ to the same point\, equivalently\, permutations $\sigma$\nand $\pi$ 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 Erd\H{o}s-Ko-Rado property.\n\nOne 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.\n\nAn 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.\n\nZoom link:\nhttps://us02web.zoom.us/j/86861499971?pwd=rTDAaju0TCu24asnaBGvkuNlT11KZ1.1\n\nMeeting ID: 868 6149 9971\nPasscode: 325258
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-27/
LOCATION:Online via Zoom
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="jeannette Janssen":MAILTO:jeannette.janssen@dal.ca
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20250212T153000
DTEND;TZID=UTC:20250212T163000
DTSTAMP:20260610T162222
CREATED:20250211T123857Z
LAST-MODIFIED:20250211T124101Z
UID:7937-1739374200-1739377800@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar
DESCRIPTION:Time: 3:30 pm\, Atlantic time\, (4:00 pm NST) Wednesday\, Feb. 12\nSpeaker: Robert Bailey\, Memorial University\nTitle: Computer constructions of distance-regular graphs with primitive automorphism groups\n\nAbstract:\nA 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.\n\nThe 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.\n \nZoom link:\nhttps://us02web.zoom.us/j/86861499971?pwd=rTDAaju0TCu24asnaBGvkuNlT11KZ1.1\n\nMeeting ID: 868 6149 9971\nPasscode: 325258
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-26/
LOCATION:Online via Zoom
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="jeannette Janssen":MAILTO:jeannette.janssen@dal.ca
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20250205T153000
DTEND;TZID=UTC:20250205T163000
DTSTAMP:20260610T162222
CREATED:20250130T120621Z
LAST-MODIFIED:20250130T120621Z
UID:7934-1738769400-1738773000@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar
DESCRIPTION:Kemeny’s constant for Markov chains and random walks on graphs\nSpeaker: Jane Breen\, Ontario Tech University\n\nKemeny’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.\n \nZoom link:\nhttps://us02web.zoom.us/j/86861499971?pwd=rTDAaju0TCu24asnaBGvkuNlT11KZ1.1\n\n\nMeeting ID: 868 6149 9971\nPasscode: 325258
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-25/
LOCATION:Online via Zoom
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="jeannette Janssen":MAILTO:jeannette.janssen@dal.ca
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20250129T153000
DTEND;TZID=UTC:20250129T163000
DTSTAMP:20260610T162222
CREATED:20250124T114752Z
LAST-MODIFIED:20250124T115307Z
UID:7921-1738164600-1738168200@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar
DESCRIPTION:Switching m-edge coloured graphs\nSpeaker: Gary MacGillivray\, University of Victoria\n\nAbstract:\n\nAn 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. \nWe consider the following problems and their solutions.  For a fixed subgroup \Gamma of S_m:\n1) determine the number of equivalence classes of k-vertex m-edge-coloured graphs under switching with respect to \Gamma.\n2) how hard is it to determine whether given m-edge-coloured graphs G and H are \Gamma-switch equivalent?\n3) 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.) \nWe will also discuss extending these results to (m\,n)-mixed graphs.  These have m different colours of edges and n different colours of arcs. \n\n \nZoom link:\nhttps://us02web.zoom.us/j/86861499971?pwd=rTDAaju0TCu24asnaBGvkuNlT11KZ1.1\n\n\nMeeting ID: 868 6149 9971\nPasscode: 325258
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-24/
LOCATION:Online via Zoom
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="jeannette Janssen":MAILTO:jeannette.janssen@dal.ca
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20250122T153000
DTEND;TZID=UTC:20250122T163000
DTSTAMP:20260610T162222
CREATED:20250118T104832Z
LAST-MODIFIED:20250118T104832Z
UID:7875-1737559800-1737563400@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar
DESCRIPTION:Ramsey numbers of signed graphs\nBen Seamone\, Dawson College and Université de Montréal\n\nAbstract:\nNathan Acheampong (Université de Montréal) Francis Clavette (Université de Montréal)\nGeˇna Hahn (Université de Montréal) Margaux Marseloo (Université Paris-Saclay) Viktor\nPaardekooper (Université de Montréal)\, and Ben Seamone* (Dawson College & Université de Montréal)\n\nA signed graph is a pair (G\, σ) where G = (V\,E) is a graph and σ : E(G) → {+\, −} is\na signature which assigns a sign to each edge of G. One well-studied operation on signed\ngraphs is that of switching at a vertex v ∈ V (G)\, by which we mean that every edge incident\nto v has its sign changed. Two signed graphs are called equivalent if one can be obtained\nfrom the other by a sequence of vertex switches.\n\nWe call a complete signed graph positive (negative) if every edge is positive (negative). We\nstudy the following Ramsey problem on signed graphs – for positive integers s and t\, what\nis the smallest n such that every signed complete graph on n vertices has an equivalent\nsigned complete graph containing either a negative Ks or positive Kt? This “signed Ramsey\nnumber” is denoted r±(s\, t). We show how a variety of approaches lead to upper and lower\nbounds on r±(s\, t)\, settle an open problem by establishing the exact value of r±(4\, t) for\nevery t\, and determine the asymptotics of r±(5\, t) and r±(6\, t).\n \nZoom link:\nhttps://us02web.zoom.us/j/86861499971?pwd=rTDAaju0TCu24asnaBGvkuNlT11KZ1.1\n\nMeeting ID: 868 6149 9971\nPasscode: 325258
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-23/
LOCATION:Online via Zoom
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="jeannette Janssen":MAILTO:jeannette.janssen@dal.ca
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20250115T153000
DTEND;TZID=UTC:20250115T163000
DTSTAMP:20260610T162222
CREATED:20250110T114756Z
LAST-MODIFIED:20250110T114821Z
UID:7869-1736955000-1736958600@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar
DESCRIPTION:Speakers: Prangya Parida\, U. Ottawa\, and Kiara McDonald\, U. Victoria\nZoom link:  https://us02web.zoom.us/j/86415230827?pwd=QUxLUnlMdWYzL05zSUJ4bnBCOUJnZz09\n\n—————————————————\nPrangya Parida:\nTitle: Cover-free families on graphs\n\nAbstract: 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.\n   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.\n   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.\n   This is joint work with Lucia Moura.\n\n——————————————————\nKiara McDonald:\nTitle: Broadcast Independence in Trees\n\n\nAbstract: 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. \nOur 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).
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-22/
LOCATION:Online via Zoom
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="jeannette Janssen":MAILTO:jeannette.janssen@dal.ca
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20241127T153000
DTEND;TZID=UTC:20241127T163000
DTSTAMP:20260610T162222
CREATED:20241121T122556Z
LAST-MODIFIED:20241121T122556Z
UID:7806-1732721400-1732725000@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar
DESCRIPTION:Speaker: Iain Beaton\, Acadia University\nTitle: Reconfiguring minimal dominating sets under a generalization of token sliding\n\nAbstract:\nA 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.\n\nZoom link:\nhttps://us02web.zoom.us/j/86861499971?pwd=rTDAaju0TCu24asnaBGvkuNlT11KZ1.1\n\nMeeting ID: 868 6149 9971\nPasscode: 325258
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-21/
LOCATION:Online via Zoom
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="jeannette Janssen":MAILTO:jeannette.janssen@dal.ca
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20241106T153000
DTEND;TZID=UTC:20241106T163000
DTSTAMP:20260610T162222
CREATED:20241101T102124Z
LAST-MODIFIED:20241101T102807Z
UID:7778-1730907000-1730910600@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar
DESCRIPTION:On the two table case of the directed Oberwolfach problem\nSpeaker: Alice Lacaze-Masmonteil\, University of Regina\n\nA directed variant of the famous Oberwolfach problem\, the directed Oberwolfach problem considers\nthe following scenario. Given n people seated at t round tables of size m1\,m2 . . . \,mt \, respectively\,\nsuch that m1+m2+· · ·+mt = n\, does there exist a set of n−1 seating arrangements such\nthat each person is seated to the right of every other person precisely once? I will first demonstrate\nhow this problem can be formulated as a type of graph-theoretic problem known as a cycle decomposition\nproblem. Then\, I will discuss a particular style of construction that was first introduced\nby R. Häggkvist in 1985 to solve several cases of the original Oberwolfach problem. Lastly\, I will\nshow how this approach can be adapted to the directed Oberwolfach problem\, thereby allowing\nus to obtain solutions for previously open cases. Certain results discussed in this talk arose from\ncollaboration with Daniel Horsley.\n\nZoom link:\nhttps://us02web.zoom.us/j/86861499971?pwd=rTDAaju0TCu24asnaBGvkuNlT11KZ1.1\n\nMeeting ID: 868 6149 9971\nPasscode: 325258
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-20/
LOCATION:Online via Zoom
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="jeannette Janssen":MAILTO:jeannette.janssen@dal.ca
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20241023T153000
DTEND;TZID=UTC:20241023T163000
DTSTAMP:20260610T162222
CREATED:20241018T101206Z
LAST-MODIFIED:20241018T101259Z
UID:7744-1729697400-1729701000@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar
DESCRIPTION:Speaker #1: Peter Collier\, Dalhousie University\nTitle #1: Zero Forcing on Twisted Hypercubes\n\nAbstract #1:\nThe 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 $2^{k-1}-2^{k-3}+1$.\n\n\nSpeaker #2: Alexander Clow\, Simon Fraser University\nTitle #2: Cornering Robots and Synchronizing Automata\n\n\nAbstract #2:\nA 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).\nIn 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).\n\n\nZoom link:\nhttps://us02web.zoom.us/j/86861499971?pwd=rTDAaju0TCu24asnaBGvkuNlT11KZ1.1\n\nMeeting ID: 868 6149 9971\nPasscode: 325258
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-18/
LOCATION:Online via Zoom
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="jeannette Janssen":MAILTO:jeannette.janssen@dal.ca
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20241002T153000
DTEND;TZID=UTC:20241002T163000
DTSTAMP:20260610T162222
CREATED:20240928T105843Z
LAST-MODIFIED:20240928T105843Z
UID:7719-1727883000-1727886600@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar
DESCRIPTION:The Martin Invariant and Other Results on the Interlace Polynomials \nJosephine Reynes\, University of Waterloo \nThere 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. \nZoom link:\nhttps://us02web.zoom.us/j/86861499971?pwd=rTDAaju0TCu24asnaBGvkuNlT11KZ1.1 \nMeeting ID: 868 6149 9971\nPasscode: 325258
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-17/
LOCATION:Online via Zoom
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="jeannette Janssen":MAILTO:jeannette.janssen@dal.ca
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20240925T150000
DTEND;TZID=UTC:20240925T163000
DTSTAMP:20260610T162222
CREATED:20240925T124502Z
LAST-MODIFIED:20240925T124502Z
UID:7696-1727276400-1727281800@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar
DESCRIPTION:Recolouring Graphs: Decompositions\, A Dichotomy Theorem and Frozen   Colourings \nSpeaker: Kathie Cameron\, Wilfrid Laurier University \nA 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.\n\nWe 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.\n\nDecompositions 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.\n\nA 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.\nThis is joint work with Manoj Belavadi\, Elias Hildred\, Owen Merkel and Dewi Sintiari.\n\n\nZoom link:\nhttps://us02web.zoom.us/j/86861499971?pwd=rTDAaju0TCu24asnaBGvkuNlT11KZ1.1\n\nMeeting ID: 868 6149 9971\nPasscode: 325258
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-16/
LOCATION:Online via Zoom
CATEGORIES:AARMS Atlantic Graph Theory Seminar
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20240918T153000
DTEND;TZID=UTC:20240918T163000
DTSTAMP:20260610T162222
CREATED:20240915T122521Z
LAST-MODIFIED:20240915T122521Z
UID:7672-1726673400-1726677000@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar
DESCRIPTION:Title: How do we use graphs to transmit quantum information? \nTime: 3.30pm\, Atlantic time\, (1:30\, CDT) Wednesday Sept. 18 \nSpeaker: Hermie Monterde\, University of Manitoba \nAbstract: \nIn 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. \n\nZoom link: \nhttps://us02web.zoom.us/j/86861499971?pwd=rTDAaju0TCu24asnaBGvkuNlT11KZ1.1
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-15/
LOCATION:Zoom seminar
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="jeannette Janssen":MAILTO:jeannette.janssen@dal.ca
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20240306T153000
DTEND;TZID=UTC:20240306T163000
DTSTAMP:20260610T162222
CREATED:20240301T112625Z
LAST-MODIFIED:20240301T112625Z
UID:7577-1709739000-1709742600@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar
DESCRIPTION:Induced subgraphs and treewidth\nSpeaker: Sophie Spirkl\, University of Waterloo\nAbstract: Treewidth is a measure of the complexity of a graph and has both structural and algorithmic consequences. While results of Robertson and Seymour characterize which minors appear in graphs of large treewidth\, the same question is still open for induced subgraphs. I will present some recent results towards an answer to this question\, in particular\, about when excluding a finite set of induced subgraphs leads to the answer being “what we expect”. Joint work with Bogdan Alecu\, Maria Chudnovsky\, and Sepehr Hajebi. \n\nJoin Zoom Meeting\nhttps://us02web.zoom.us/j/86415230827?pwd=QUxLUnlMdWYzL05zSUJ4bnBCOUJnZz09\n\nMeeting ID: 864 1523 0827\nPasscode: 835547\n\n\nLive viewing with refreshments in Chase 227\, Dalhousie University (bring your own mug for tea.)
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-14/
LOCATION:Online via Zoom
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="jeannette Janssen":MAILTO:jeannette.janssen@dal.ca
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20240228T153000
DTEND;TZID=UTC:20240228T163000
DTSTAMP:20260610T162222
CREATED:20240228T114600Z
LAST-MODIFIED:20240228T114626Z
UID:7574-1709134200-1709137800@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar
DESCRIPTION:Pursuit-evasion on Graphs\nTrent Marbach\, Toronto Metropolitan University \nThe study of pursuit-evasion on graphs looks at games played between two adversaries\, with one player tasked with alluding capture from the other on the graph. We will describe these types of games in general\, although we will take a particular focus on two games: the Cops and Robber game\, and the Localization game. A famous open conjecture for the Cops and Robber game has spurred recent work in the area\, and we show how this work connects to various graph theory topics\, including isoperimetry\, network search\, and width parameters. We will also provide some new applications that have resulted from this work. \nLive viewing at Dalhousie in Chase 227 (bring your own mug for tea). \n——————————\nJoin Zoom Meeting\nhttps://us02web.zoom.us/j/86415230827?pwd=QUxLUnlMdWYzL05zSUJ4bnBCOUJnZz09\n\nMeeting ID: 864 1523 0827\nPasscode: 835547
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-13/
LOCATION:Online via Zoom
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="jeannette Janssen":MAILTO:jeannette.janssen@dal.ca
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20240221T153000
DTEND;TZID=UTC:20240221T163000
DTSTAMP:20260610T162222
CREATED:20240219T131416Z
LAST-MODIFIED:20240219T131514Z
UID:7556-1708529400-1708533000@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar
DESCRIPTION:Speaker: Ada Chan\, York University\nTitle: Polygamy in state transferAbstract:Let $X$ be a graph and $H$ be a Hermitian matrix associated with $X$.   The continuous-time quantum walk with Hamiltonian $H$ isdefined by the time-dependent unitary matrix\begin{equation*}U(t)=e^{i t H}.\end{equation*}Perfect state transfer occurs from vertex $a$ to vertex $b$ at time $\tau$ is $\vert U(\tau)_{b\,a}\vert = 1$.   This phenomenon is relevant for information transmission in a quantum spin network.   For real and symmetric Hamiltonians\, it is known that perfect state transfer can occur from a vertex to at most one other vertex\,mand that graphs with perfect state transfer are rare.    A relaxation\, called pretty good state transfer\, occurs from $a$ to $b$ if $\vert U(\tau)_{b\,a}\vert$ gets arbitrarily close one.  Pal and Bhattacharjya discover a graph with four vertices admitting pairwise pretty good state transfer. In this talk\, we present a family of graphs that admit pairwise pretty good state transfer in an arbitrarily large set of vertices. We compare this polygamous behaviour to walks with Hamiltonians that contain non-real entries.\n\n\nJoin Zoom Meeting\nhttps://us02web.zoom.us/j/86415230827?pwd=QUxLUnlMdWYzL05zSUJ4bnBCOUJnZz09\n\nMeeting ID: 864 1523 0827\nPasscode: 835547
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-12/
LOCATION:Online via Zoom
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="jeannette Janssen":MAILTO:jeannette.janssen@dal.ca
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20240214T153000
DTEND;TZID=UTC:20240214T163000
DTSTAMP:20260610T162222
CREATED:20240211T201100Z
LAST-MODIFIED:20240211T201216Z
UID:7549-1707924600-1707928200@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar
DESCRIPTION:Speaker: Andrew Beveridge\, Macalester College\nTitle: Approval Ballot Triangles\nTime: Wednesday\, February 14\, 3.30pm Atlantic time\nLive viewing for local participants in Chase 227\, Dalhousie University\n \nBertrand’s Ballot Problem enumerates the number of ways to count ballots so that candidate 1 never trails candidate 2. We generalize this problem by considering an approval ballot election between $n$ candidates. In an approval ballot election\, each voter endorses a subset of candidates\, rather than voting for just one person. The general approval ballot problem becomes: how many ways can the ballots be counted so that candidate $k$ never trails candidate $k+1$? This formulation yields a family of binary triangular arrays\, called approval ballot triangles (ABTs)\, that are in bijection with totally symmetric self-complementary plane partitions. We show that ABTs unify three different TSSCPP families of triangular arrays. We then further the connection between TSSCPPs and ballot problems by giving a decomposition of a strict-sense ballot into a list of sequentially compatible ABTs\n \nJoin Zoom Meeting\nhttps://us02web.zoom.us/j/86415230827?pwd=QUxLUnlMdWYzL05zSUJ4bnBCOUJnZz09\n \nMeeting ID: 864 1523 0827\nPasscode: 835547
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-11/
LOCATION:Online via Zoom
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="jeannette Janssen":MAILTO:jeannette.janssen@dal.ca
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20240206T153000
DTEND;TZID=UTC:20240206T163000
DTSTAMP:20260610T162222
CREATED:20240205T201726Z
LAST-MODIFIED:20240205T201815Z
UID:7536-1707233400-1707237000@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar
DESCRIPTION:Zoom link below. Live viewing for local participants in Chase 227 (tea-drinkers are encouraged to bring their own mug).\n \nSpeaker: Evelyn Smith-Roberge\, Georgia Tech\nTitle:Correspondence Packings of Planar Graphs\n \nAbstract: Suppose a graph G has list chromatic number k. It is easy to see that if L is a (k+1)-list assignment for G\, then G admits two L-colourings f and g where f(v) =/= g(v) for every vertex v in the graph. But what if we want still more disjoint L-colourings without making our lists too big? In this talk\, I will discuss recent progress towards determining the list packing number of various classes of planar graphs: that is\, the smallest number k such that if L is a k-list assignment for an arbitrary graph G in the class under study\, then L can be decomposed into k disjoint L-colourings. All results I will discuss also hold in the correspondence colouring framework. Joint work with Daniel Cranston.\n \nJoin ZOOM Meeting:\nhttps://us02web.zoom.us/j/86415230827?pwd=QUxLUnlMdWYzL05zSUJ4bnBCOUJnZz09\n\nMeeting ID: 864 1523 0827\nPasscode: 835547
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-10/
LOCATION:Online via Zoom
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="jeannette Janssen":MAILTO:jeannette.janssen@dal.ca
END:VEVENT
END:VCALENDAR