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BEGIN:VEVENT
DTSTART;TZID=UTC:20230322T153000
DTEND;TZID=UTC:20230322T163000
DTSTAMP:20260611T004152
CREATED:20230319T132045Z
LAST-MODIFIED:20230319T132045Z
UID:7186-1679499000-1679502600@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar: Mohammad Salavatipour\, U. Alberta
DESCRIPTION:Approximation Schemes for Resource Minimization for Fire Containment\nResource Minimization Fire Containment (RMFC) is a natural model for optimal inhibition of\nharmful spreading phenomena on a graph. In the RMFC problem on trees\, we are given an undirected\ntree G\, and a vertex r where the fire starts at\, called root. At each time step\, the firefighters\ncan protect up to B vertices of the graph while the fire spreads from burning vertices to all their\nneighbors that have not been protected so far. The task is to find the smallest B that allows for\nsaving all the leaves of the tree. The problem is hard to approximate up to any factor better than 2\neven on trees unless P = NP. \nIn this talk we present an asymptotic QPTAS for RMFC on trees. More specifically\, let \eps > 0\,\nand F be an instance of RMFC where the optimum number of firefighters to save all the leaves is\nOPT(F). We present an algorithm which uses at most \ceil(1 + \eps )OPT(F)\rceil many firefighters at each\ntime step and runs in time n^O(\log\log n). This suggests that the existence of an asymptotic PTAS is\nplausible especially since the exponent is O(log log n). \n————————————————————-\nJoin Zoom Meeting\nhttps://us02web.zoom.us/j/86415230827?pwd=QUxLUnlMdWYzL05zSUJ4bnBCOUJnZz09 \nMeeting ID: 864 1523 0827\nPasscode: 835547
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-mohammad-salavatipour-u-alberta/
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:20230315T153000
DTEND;TZID=UTC:20230315T163000
DTSTAMP:20260611T004152
CREATED:20230315T123936Z
LAST-MODIFIED:20230315T123936Z
UID:7144-1678894200-1678897800@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar: Caleb Jones and Rylo Ashmore (Memorial University)
DESCRIPTION:Speaker 1: Caleb Jones\, Memorial University\n \nTitle: Extending Graph Burning to Hypergraphs\n \nAbstract:\nWe introduce a round-based model much like graph burning which applies to hypergraphs. The rules for this new model are very natural\,and generalize the original model of graph burning. We also introduce a variant called lazy hypergraph burning\, along with a new parameter\, the lazy burning number. Interestingly\, lazily burning a graph is trivial\, while lazily burning a hypergraph can be quite complicated. Moreover\, the lazy burning model is a useful tool for analyzing the round-based model on hypergraphs. We obtain bounds on the burning number and lazy burning number of a hypergraph in terms of its parameters.\n \n \nSpeaker 2: Rylo Ashmore\, Memorial University\n \nTitle: Herding Cats Stuck in Trees.\n \nAbstract:\nIn the game of Cat Herding on a graph\, one player (the herder) will omnipresently delete edges\, while the other player (the cat) is on a vertex of the graph\, and will move along any path to a new vertex. Eventually\, the cat is isolated on a single vertex\, and the cat’s objective is to delay this event\, while the herder tries to hasten it. In an optimally played game\, the number of cuts the herder made to isolate the cat is the cat number of the graph. In this talk\, we will investigate this graph parameter for both dense and sparse graphs. We will see an argument that the asymptotic behaviour of the cat number of complete graphs is n^2/3. We also look at an unexpected connection between cat herding on trees and Fibonacci numbers. In particular\, we will see that trees with maximum cat number amongst graphs with n vertices have cat number asymptotically log_φ (n).\n\nZoom link: https://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-caleb-jones-and-rylo-ashmore-memorial-university/
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:20230308T153000
DTEND;TZID=UTC:20230308T163000
DTSTAMP:20260611T004152
CREATED:20230304T105511Z
LAST-MODIFIED:20230304T105511Z
UID:7138-1678289400-1678293000@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar: Lucas Mol\, Thomson Rivers University
DESCRIPTION:Avoiding additive powers in words\nA word is a sequence of symbols taken from some finite alphabet. A square is a word of the form xx\, where x is a nonempty word. It is well-known that there are infinite words over an alphabet of size 3 that contain no squares. Suppose now that the alphabet is some finite subset of the integers. An additive square is a word of the form xx’\, where x and x’ have the same nonzero length and the same sum. Additive cubes\, fourth powers\, etc.\, are defined similarly. We present a method for proving that certain types of infinite words contain no additive k-powers. This is joint work with James Currie\, Narad Rampersad\, and Jeffrey Shallit.\n\n\n—————————————————————————————————————-\n\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-lucas-mol-thomson-rivers-university/
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:20230301T153000
DTEND;TZID=UTC:20230301T163000
DTSTAMP:20260611T004152
CREATED:20230226T121131Z
LAST-MODIFIED:20230226T121131Z
UID:7132-1677684600-1677688200@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar: Isaac McMullin and Ian George\, Dalhousie University
DESCRIPTION:Speaker 1: Isaac McMullin \nExistence of Optimal Split Reliability Polynomials\nOne of the most common models of robustness of a graph against random failures has all vertices operational\, but the edges independently operational with probability p. On one hand\, one can ask for the probability that all vertices can communicate (all-terminal reliability) while on the other hand\, we can ask that two specific vertices (or terminals) can communicate with each other (two-terminal reliability). While both of these questions have been well-studied\, they are both increasing functions of the edge probability. One new approach is split reliability\, where for two fixed vertices s and t\, we consider the probability that every vertex communicates with one of s or t\, but not both. The split reliability of G is a polynomial function of p that for connected graphs is 0 both at p=0 and at p=1. In this presentation\, we explore the existence for fixed numbers n>=2 and m>=n-1 of an optimal connected (n\,m)-graph G_(n\,m) for split reliability\, that is\, a connected graph with n vertices and m edges for which for any other such graph H\, the split reliability of G_(n\,m) is at least as large as that of H\, for all values of p in [0\,1]. Unlike the similar problems for all-terminal and two-terminal reliability\, where only partial results are known\, we completely solve the issue for split reliability\, where we show that there is an optimal (n\,m)-graph for split reliability if and only if n<=3\, m=n-1\, or n=m=4. \n  \n\n\nSpeaker 2: Ian George \nDegree Polynomials of Graphs \nIn this talk we introduce the Degree Polynomial of a graph.  This polynomial is defined to be the generating function of the sequence (a_0\, a_1\, a_2\, …) where a_k is the number of vertices of degree k in a graph.  Little has been published about this polynomial other than its behaviour under graph operations.  We will explore some basic properties of this polynomial\, and see what information it encodes about a graph.  Then we will discuss the roots of degree polynomials\, or degree roots\, giving some bounds and density results.  Along the way\, the degree polynomials and degree roots for certain families of graphs will be highlighted. \n\nThe talks will be held in room 227 in the Chase building at Dalhousie\, and streamed via zoom \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-isaac-mcmullin-and-ian-george-dalhousie-university/
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:20230215T153000
DTEND;TZID=UTC:20230215T163000
DTSTAMP:20260611T004152
CREATED:20230213T124408Z
LAST-MODIFIED:20230213T124408Z
UID:7121-1676475000-1676478600@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar: Jérémie Turcotte\, Université de Montréal
DESCRIPTION:Progress towards the Burning Number Conjecture\nThe burning number b(G) of a graph G is the smallest integer k such that G can be covered by k balls of radii respectively 0\,…\,k-1\, and was introduced independently by Brandenburg and Scott at Intel as a transmission problem on processors and Bonato\, Janssen and Roshanbin as a model for the spread of information in social networks. The Burning Number Conjecture claims that b(G)<=\lceil\sqrt{n}\rceil\, where n is the number of vertices of G. This bound is tight for paths. The previous best bound for this problem\, by Bastide et al.\, was b(G)<= \sqrt{\frac{4n}{3}}+1. We prove that the Burning Number Conjecture holds asymptotically\, that is b(G)<= (1+o(1))\sqrt{n}. Following a brief introduction to graph burning\, this talk will focus on the general ideas behind the proof. \nMeeting ID: 885 9352 1895\nPasscode: 522241
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-jeremie-turcotte-universite-de-montreal/
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:20230208T153000
DTEND;TZID=UTC:20230208T163000
DTSTAMP:20260611T004152
CREATED:20230213T124145Z
LAST-MODIFIED:20230213T124512Z
UID:7119-1675870200-1675873800@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar: Jason Brown\, Dalhousie University
DESCRIPTION:Colourings\, Polynomials and Roots\nA lot has happened since graph colourings first arose as an applied problem in cartography – do four colours always suffice to distinguish countries when colouring a map? Along the way to the proof\, the related enumeration function to count the number of k-colourings was proposed. While the latter didn’t help much in the quest for the Four Colour Theorem\, it did lead to a fascinating branch of graph theory\, namely chromatic polynomials. While polynomials are the simplest of functions\, their properties can take you deep within mathematics. In this talk I will describe some recent result on chromatic polynomials and their offshoots\, connecting to commutative algebra as well as real and complex analysis. And on our trip\, we visit with some old friends\, including Charles Hermite\, Jacques Sturm\, and Carl Gauss. \nMeeting ID: 831 4765 9865\nPasscode: 505092
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-jason-brown-dalhousie-university/
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:20230118T153000
DTEND;TZID=UTC:20230118T163000
DTSTAMP:20260611T004152
CREATED:20230113T131357Z
LAST-MODIFIED:20230113T131357Z
UID:7049-1674055800-1674059400@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar: Jane (Pu) Gao\, University of Waterloo
DESCRIPTION:Conditions for perfect matchings in random sparse bipartite graphs \nGiven a uniformly random sparse matrix A\, with specified number of nonzero entries in columns and rows\, we determine when A has full row rank over a finite field. As a corollary\, by considering A as the adjacency matrix of a bipartite graph\, our result determines the conditions for the existence of a perfect matching in various models of random sparse bipartite graphs. We will explore some useful insight from statistical physics that guides our probabilistic combinatorial proof. This is joint work with Coja-Oghlan\, Hahn-Klimroth\, Lee\, Mueller and Rolvien. \n  \nJoin Zoom Meeting\nhttps://us02web.zoom.us/j/82306017918?pwd=Q0hKTElTMzQxaythWmE3SnhtbGZDUT09\n\nMeeting ID: 823 0601 7918\nPasscode: 045489
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-jane-pu-gao-university-of-waterloo/
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:20230111T153000
DTEND;TZID=UTC:20230111T163000
DTSTAMP:20260611T004152
CREATED:20230106T111103Z
LAST-MODIFIED:20230106T113715Z
UID:7016-1673451000-1673454600@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar: Pawel Pralat\, Metropolitan University of Toronto
DESCRIPTION:An Unsupervised Framework for Comparing Graph Embeddings\nThe goal of many machine learning applications is to make predictions or discover new patterns using graph-structured data as feature information. In order to extract useful structural information from graphs\, one might want to try to embed it in a geometric space by assigning coordinates to each node such that nearby nodes are more likely to share an edge than those far from each other. There are many embedding algorithms (based on techniques from linear algebra\, random walks\, or deep learning) and the list constantly grows. As a result\, selecting the best embedding is a challenging task and very often requires domain experts. Our general framework assigns the divergence score to each embedding which\, in an unsupervised learning fashion\, distinguishes good from bad embeddings. In order to benchmark embeddings\, we generalize the Chung-Lu random graph model to incorporate geometry.\n\n\nJoin Zoom Meeting\nhttps://us02web.zoom.us/j/82306017918?pwd=Q0hKTElTMzQxaythWmE3SnhtbGZDUT09\n\nMeeting ID: 823 0601 7918\nPasscode: 045489
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-pawel-pralat-metropolitan-university-of-toronto/
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:20221130T153000
DTEND;TZID=UTC:20221130T163000
DTSTAMP:20260611T004152
CREATED:20221124T144803Z
LAST-MODIFIED:20230106T112807Z
UID:6970-1669822200-1669825800@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar: Sebastian Cioaba\, University of Delaware
DESCRIPTION:Addressing graphs and hypergraphs \nIn 1970s\, Ron Graham and Henry Pollak introduced the notion of graph addressing which is a labeling of the vertices of an undirected graph by words of the same length over the alphabet {0\,1\,*} such that the distance between any two vertices equals the number of positions in their labels/addresses where one vertex has a 0 and the other one has a 1. The minimum of length of such words has been investigated by various people and is closely related to the partition of the edge set of the graph into bicliques (complete bipartite subgraphs). In this talk\, I will describe some recent results related to this parameter for various families of graphs and the corresponding problem for hypergraphs. \nZoom info:\n\nhttps://us02web.zoom.us/j/87564743456?pwd=cTdkMGxYQ0dGaG4zdkZpeFVlTmsrQT09 \nMeeting ID: 875 6474 3456\nPasscode: 259500
URL:https://aarms.math.ca/event/atlantic-graph-theory-semibar-sebastian-cioaba-university-of-delaware/
LOCATION:Online via Zoom
CATEGORIES:AARMS Atlantic Graph Theory Seminar,Atlantic Graph Theory Seminar
ORGANIZER;CN="jeannette Janssen":MAILTO:jeannette.janssen@dal.ca
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20220413T153000
DTEND;TZID=UTC:20220413T163000
DTSTAMP:20260611T004152
CREATED:20220411T113741Z
LAST-MODIFIED:20220411T113741Z
UID:6641-1649863800-1649867400@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar: Aysel Erey (Gebze Technical University\, Turkey)
DESCRIPTION:Graph polynomials\n\nIn this talk\, I will discuss various aspects of several graph polynomials such as the location of their roots\, their combinatorial properties and extremal questions.\n\nJoin Zoom Meeting: link
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-aysel-erey-gebze-technical-university-turkey/
LOCATION:Zoom seminar
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="Jason Brown":MAILTO:jason.brown@dal.ca
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20220406T153000
DTEND;TZID=UTC:20220406T163000
DTSTAMP:20260611T004152
CREATED:20220404T142531Z
LAST-MODIFIED:20220404T142531Z
UID:6637-1649259000-1649262600@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar: John Engbers (Marquette University)
DESCRIPTION:Extremal questions for vertex colorings of graphs\n\nFor graphs $G$ and $H$\, an $H$-coloring of $G$ is a map from the vertices of $G$ to the vertices of $H$ so that an edge in $G$ is mapped to an edge in $H$.  The graph $H$ can be thought of as the allowable coloring scheme: its vertices are the colors used and its edges indicating colors that can appear on the endpoints of an edge in $G$. When the graph $H$ is the complete graph $K_q$\, an $H$-coloring corresponds to a proper vertex coloring of $G$ with $q$ colors; when $H$ is an edge with one looped endvertex\, an $H$-coloring corresponds to an independent set in $G$.After familiarizing ourselves with the notion of an $H$-coloring\, we will consider the following extremal graph theory question: given a family of graphs and an $H$\, which graph in the family has the most number of $H$-colorings\, and which has the least number of $H$-colorings?  We will discuss some things that are known (and not known!) in a variety of families\, including trees and graphs with a fixed minimum degree.\n\n\nJoin Zoom Meeting: link\n\n\n 
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-john-engbers-marquette-university/
LOCATION:Zoom seminar
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="Jason Brown":MAILTO:jason.brown@dal.ca
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20220316T153000
DTEND;TZID=UTC:20220316T163000
DTSTAMP:20260611T004152
CREATED:20220314T110128Z
LAST-MODIFIED:20220314T110138Z
UID:6626-1647444600-1647448200@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar: Theodore Kolokolnikov (Dalhousie)
DESCRIPTION:We study the algebraic connectivity for several classes of random semi-regular graphs. For large random semi-regular bipartite graphs\, we explicitly compute both their algebraic connectivity and as well as the full spectrum distribution. For an integer d in [3\,8]\, we find families of random semi-regular graphs that have higher algebraic connectivity than a random d-regular graphs with the same number of vertices and edges. On the other hand\, we show that regular graphs beat semi-regular graphs when d >8. More generally\, we study random semi-regular graphs whose average degree is d\, not necessary an integer. This provides a natural generalization of a d-regular graph in the case of a non-integer d. We characterise their algebraic connectivity in terms of a root of a certain 6th-degree polynomial. Finally\, we construct a small-world-type network of average degree 2.5 with a relatively high algebraic connectivity. We also propose some related open problems and conjectures.
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-theodore-kolokolnikov-dalhousie/
LOCATION:Online via Zoom
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="Jason Brown":MAILTO:jason.brown@dal.ca
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20220309T153000
DTEND;TZID=UTC:20220309T163000
DTSTAMP:20260611T004152
CREATED:20220307T121100Z
LAST-MODIFIED:20220307T122041Z
UID:6619-1646839800-1646843400@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar: Pjotr Buys (University of Amdsterdam)
DESCRIPTION:About a year ago Jason Brown spoke in our seminar (of the university of Amsterdam) about the two-terminal reliability polynomial and left us with some questions about the closure of the complex zeros of all such polynomials (the zero-locus). In this talk I will define a way to capture\, for a certain parameter\, whether the set of all two-terminal reliability polynomials behaves chaotically around this parameter or not\, i.e. whether this parameter is active or passive. I call the set of all active parameters the activity-locus and I will show that it is equal to the zero-locus. I will use this framework to prove some fun things about the zero-locus. Although I have not yet figured out how to use this to answer any of the open questions posed by Jason\, I am hopeful it might be a step in the right direction. \n\nJoin Zoom Meeting: link
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-pjotr-nuys-university-of-amdsterdam/
LOCATION:Online via Zoom
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="Jason Brown":MAILTO:jason.brown@dal.ca
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20220216T153000
DTEND;TZID=UTC:20220216T163000
DTSTAMP:20260611T004152
CREATED:20220215T113731Z
LAST-MODIFIED:20220215T113757Z
UID:6608-1645025400-1645029000@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar: Ferenc Bencs (University of Amsterdam)
DESCRIPTION:In this talk\, I will show regions that contain no complex zeros the edge-cover polynomials of hypergraphs. The edge cover polynomial of a graph $G$ is the generating function of edges that covers $V(G)$. It is known that the zeros of this polynomial have length at most $\frac{(2+\sqrt{3})^2}{1+\sqrt{3}}$\, that we strengthen by showing that it is at most $4$.  We use the general subgraph counting polynomial of Wagner to establish this result along with its generalization for the edge cover polynomial of hypergraphs. As another example\, we will establish a new bound on the length of the zeros of the domination and total domination polynomials of graphs in terms of the maximum degree.\n\n\n\n\n\nJoint work with P\’eter Csikv\’ari and  Guus Regts.
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-ferenc-bencs-university-of-amsterdam/
LOCATION:Zoom seminar
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="Jason Brown":MAILTO:jason.brown@dal.ca
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20220209T153000
DTEND;TZID=UTC:20220209T163000
DTSTAMP:20260611T004152
CREATED:20220207T121303Z
LAST-MODIFIED:20220207T121303Z
UID:6584-1644420600-1644424200@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar: Margaret-Ellen Messinger (Mount Allison University)
DESCRIPTION:Reconfiguration for Dominating Sets\n\nGiven a problem and a set of feasible solutions to that problem\, the associated  reconfiguration problem involves determining whether one feasible solution to the original problem can be transformed to a different feasible solution through a sequence of allowable moves\, with the condition that the intermediate stages are also feasible solutions.  Any reconfiguration problem can be modelled with a  reconfiguration graph\, where the vertices represent feasible solutions and two vertices are adjacent if and only if the corresponding feasible solutions can be transformed to each other via em one allowable move.The domination reconfiguration graph of a graph $G$\, denoted ${\mathcal D}(G)$\, has a vertex corresponding to each dominating set of $G$ and two vertices of ${\mathcal D}(G)$ are adjacent if and only if the corresponding dominating sets differ by the deletion or addition of a single vertex.  We are interested in properties of domination reconfiguration graphs. For example\, it is easy to see that they are always connected and bipartite.  We can also characterize exactly which graphs yield domination reconfiguration graphs with Eulerian circuits.  While none has a Hamilton cycle\, we explore families of graphs whose reconfiguration graphs have Hamilton paths.\n\n\nJoin Zoom Meeting: link\n\n 
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-margaret-ellen-messinger-mount-allison-university/
LOCATION:Zoom seminar
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="Jason Brown":MAILTO:jason.brown@dal.ca
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20220202T153000
DTEND;TZID=UTC:20220202T163000
DTSTAMP:20260611T004152
CREATED:20220130T142415Z
LAST-MODIFIED:20220131T120204Z
UID:6579-1643815800-1643819400@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar: Melissa Huggan (Mount Allison)
DESCRIPTION:The Orthogonal Colouring Game\nThe Orthogonal Colouring Game is a combinatorial game in which two players alternately colour vertices of a pair of isomorphic graphs while respecting the properness and the orthogonality of the colouring. Each player aims to maximize her score\, which is the number of coloured vertices in the copy of the graph she owns. An involution $\sigma$ of a graph $G$ is strictly matched if its fixed point set induces a clique and any non-fixed point $v \in V(G)$ is connected with its image $\sigma(v)$ by an edge. \nIn this talk\, we introduce the game and our main result that the second player has a strategy to force a draw in this game for graphs that admit a strictly matched involution. We will also give a structural characterization of graphs admitting a strictly matched involution. \nThis is joint work with Stephan Dominique Andres\, Francois Dross\, Fionn Mc Inerney\, and Richard J. Nowakowski. \nJoin Zoom Meeting: link \n 
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-melissa-huggan-mount-allison/
LOCATION:Zoom seminar
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="Jason Brown":MAILTO:jason.brown@dal.ca
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20220126T153000
DTEND;TZID=UTC:20220126T163000
DTSTAMP:20260611T004152
CREATED:20220124T120023Z
LAST-MODIFIED:20220124T120023Z
UID:6576-1643211000-1643214600@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar: Andrea Burgess (UNB)
DESCRIPTION:Mutually Orthogonal Cycle Systems\nA $k$-cycle system of order $n$ is a set of $k$-cycles whose edges partition the edge set of $K_n$.  We say that two cycle systems $\mathcal{C}$ and $\mathcal{C}’$ are {\em orthogonal} if every cycle in $\mathcal{C}$ shares at most one edge with each cycle in $\mathcal{C}’$.  Orthogonal cycle systems arise naturally from simple Heffter arrays and biembeddings of cycle decompositions. \nA collection of cycle systems is {\em mutually orthogonal} if any two of the systems are orthogonal.  In this talk\, we give bounds on the number of mutually orthogonal $k$-cycle systems of order $n$ and provide constructions for sets of mutually orthogonal cyclic cycle systems. \nThis is joint work with Nicholas Cavenagh and David Pike. \nJoin Zoom Meeting: link
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-andrea-burgess-unb/
LOCATION:Zoom seminar
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="Jason Brown":MAILTO:jason.brown@dal.ca
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20220119T153000
DTEND;TZID=UTC:20220119T163000
DTSTAMP:20260611T004152
CREATED:20220116T181412Z
LAST-MODIFIED:20220116T181412Z
UID:6553-1642606200-1642609800@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar: Robert Kooij (Delft University of Technology)
DESCRIPTION:Robustness of Complex Networks \nNetwork Science aims to understand the graph structure of networks and the dynamic processes that take place on networks. Examples of processes on networks are transport of items (IP packets with digitalized  information\, cars\, containers) and diffusion (epidemics\, electric current\, water flows\, human emotions). The Network Architectures and Services Section at the Delft University of Technology contributes to the fundaments of Network Science: we investigate amongst others geometric representations of networks\, epidemic spread on networks\, spectra of  graphs and network algorithms. In addition\, we apply our mathematical knowledge to the design\, management and control of critical  infrastructures\, such as telecom networks and power grids\, in order to make these networks robust\, resilient\, efficient and reliable. In this talk we will give three examples of our results in the field of robustness of complex  networks\, namely robustness with respect to malware spread\, robustness of network controllability and the robustness of a real-world critical infrastructure. \nJoin Zoom Meeting: link
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-robert-kooij-delft-university-of-technology/
LOCATION:Zoom seminar
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="Jason Brown":MAILTO:jason.brown@dal.ca
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20220112T153000
DTEND;TZID=UTC:20220112T163000
DTSTAMP:20260611T004152
CREATED:20220109T183647Z
LAST-MODIFIED:20220109T183647Z
UID:6550-1642001400-1642005000@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar: Iain Moffat (Royal Holloway\, University of London)
DESCRIPTION:Spanning Trees and Graphs Embedded in Surfaces\n\nTo what extent is a graph determined by the trees contained in it? That is\, if we know the edge sets of each of the spanning trees (i.e.\, maximal acyclic subgraphs) in a connected graph\, then do we know the graph itself? It only takes a little bit of thought to see that the answer is “no” (e.g.\, suppose the graph is a tree).  But this “no” is really a “more or less\, yes”.   A classical result of Whitney states that we know the graph up to some simple moves. \n\nIn this talk we consider what changes if we ask this question not for graphs in the abstract\, but graphs that are embedded on surfaces.  We shall see how this question brings together a seemingly disjoint collection of topics in mathematics and brings new approaches to topological graph theory.
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-iain-moffat-royal-holloway-university-of-london/
LOCATION:Zoom seminar
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="Jason Brown":MAILTO:jason.brown@dal.ca
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20211208T153000
DTEND;TZID=UTC:20211208T163000
DTSTAMP:20260611T004152
CREATED:20211206T120336Z
LAST-MODIFIED:20211206T120336Z
UID:6547-1638977400-1638981000@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar: Sandra Kingan (Brooklyn College and Graduate Center\, CUNY)
DESCRIPTION:I will begin by giving a general overview of what it means to find monarchs for excluded minor classes of graphs and matroids. In a paper that appeared in 2018\, I used the Strong Splitter Theorem to give a short proof of Oxley’s result that the class of binary matroids with no 4-wheel minor consists of a few small matroids and an infinite family of maximal 3-connected rank r matroids known as the binary spikes. Such a family is called a monarch for the excluded minor class. This proof essentially comes down to finding the monarchs for non-regular matroids with no minors isomorphic to a 9-element rank 4 matroid known as P9 or its dual P*9. In a paper that appeared this year (Australasian Journal of Combinatorics\, 79(3)\, 302–326)\, I was able to strengthen the result by characterizing the class of binary non-regular matroids with no minor isomorphic to just P*9. The only members of this class are the rank 3 and 4 binary projective geometries\, a 16-element rank 5 matroid\, and two monarchs: the rank r binary spikes with 2r+1 elements mentioned earlier and another infinite family with 4r−5 elements. As a consequence\, a simple binary matroid of rank at least 6 with no P*9-minor has size at most r(r+1)/2 and this bound is attained by the rank r complete graph. This is one of few excluded minor classes for which the members are so precisely determined. \n  \nJoin Zoom Meeting: link
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-sandra-kingan-brooklyn-college-and-graduate-center-cuny/
LOCATION:Zoom seminar
CATEGORIES:AARMS Atlantic Graph Theory Seminar
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BEGIN:VEVENT
DTSTART;TZID=UTC:20211201T153000
DTEND;TZID=UTC:20211201T163000
DTSTAMP:20260611T004152
CREATED:20211128T200242Z
LAST-MODIFIED:20211128T200242Z
UID:6543-1638372600-1638376200@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar: James Preen (Cape Breton University)
DESCRIPTION:There are many results about triangles in graphs\, but the property that every edge in a graph is in at least one triangle seems not to have been studied before. The 4-regular case was quickly solved collaboratively following an internet posting and then written about by one author in their blog\, before being published in the Journal of Graph Theory in 2013. \nHowever\, the result that was originally wanted was a characterisation for 5-regular graphs\, and that did not emerge as smoothly. With no solution published several years later\, I started working on it and have submiited my paper resolving it in 2021. In this talk I will outline the background and the ideas used in the proof\, which involves cliques\, multiple edges and a generalisation of the the line graph construction. \nJoin Zoom Meeting: link\nTo view previous slides and talks\, click here.
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-james-preen-cape-breton-university/
LOCATION:Zoom seminar
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="Jason Brown":MAILTO:jason.brown@dal.ca
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20211117T153000
DTEND;TZID=UTC:20211117T163000
DTSTAMP:20260611T004152
CREATED:20211115T114239Z
LAST-MODIFIED:20211115T114239Z
UID:6506-1637163000-1637166600@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar: Pavol Hell (SFU)
DESCRIPTION:I will discuss a few examples where considering loops leads to interesting insights\, often allowing unifying existing results. These examples will include cops and robbers games\, graph homomorphisms\, variants of interval and chordal graphs\,\nand versions of domination. \nJoin Zoom Meeting: link
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-pavol-hell-sfu/
LOCATION:Zoom seminar
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="Jason Brown":MAILTO:jason.brown@dal.ca
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20211103T153000
DTEND;TZID=UTC:20211103T163000
DTSTAMP:20260611T004152
CREATED:20211031T172611Z
LAST-MODIFIED:20211031T172611Z
UID:6472-1635953400-1635957000@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar: Jo Ellis-Monaghan (University of Amsterdam)
DESCRIPTION:2017 saw the centennial of William Tutte\, one of the greatest mathematicians of modern times.  One of the testimonies to Tutte’s genius is that nearly everything he did proved to be a catalyst\, triggering an explosion of further investigations and opening whole new vistas of mathematics.  The Tutte polynomial is one of many such examples in his legacy.   Here we will explore some of its salient properties and some of the many directions that propagated outward from the original Tutte polynomial.  These include several ways in which the Tutte polynomial may be defined and its universality\, as well as some of its combinatorial and algebraic properties.  We will showcase information encoded in the Tutte polynomial as evaluations and specializations\, as these inform nearly every aspect of combinatorics.   Furthermore\, the scope of the Tutte polynomial is continually broadening through generalizations of either its domain or parameter space\, and we will highlight some important examples\, and touch on its interrelations with other combinatorial polynomials.  We will conclude with its particularly fruitful connections with biology and the Potts model of statistical mechanics\, and offer some open questions.
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-jo-ellis-monaghan-university-of-amsterdam/
LOCATION:Zoom seminar
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="Jason Brown":MAILTO:jason.brown@dal.ca
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BEGIN:VEVENT
DTSTART;TZID=UTC:20211027T153000
DTEND;TZID=UTC:20211027T163000
DTSTAMP:20260611T004152
CREATED:20211025T002720Z
LAST-MODIFIED:20211025T003603Z
UID:6450-1635348600-1635352200@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar: Guss Regts (University of Amsterdam)
DESCRIPTION:Improved bounds for zeros of the chromatic polynomial on bounded degree graphs\nAbout 20 years ago Sokal proved that there exists a constant C so that for any graph G\, all of the complex zeros of its chromatic polynomial are contained in the disk of radius C Delta(G) centered at 0. (Here Delta(G) denotes the maximum degree of G.) He showed that C could be taken slightly smaller than 8. This was improved to 6.91 by Fernández and Procacci. In this talk I will present an improvement to 5.02 and explain some of the ideas and ingredients of the proof. \nBased on joint work with Maurizio Moreschi\, Viresh Patel and Ayla Stam. \nJoin Zoom Meeting: link
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar/
LOCATION:Zoom seminar
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="Jason Brown":MAILTO:jason.brown@dal.ca
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20211020T153000
DTEND;TZID=UTC:20211020T163000
DTSTAMP:20260611T004152
CREATED:20211025T003426Z
LAST-MODIFIED:20211025T003520Z
UID:6454-1634743800-1634747400@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar: Viresh Patel (University of Amsterdam)
DESCRIPTION:Title: Path decompositions of random directed graphs \nIn this talk we consider the problem of partitioning the edges of a digraph into as few paths as possible. The minimum number of paths needed in such an edge decomposition is called the path number of the digraph. \nThe problem of determining the path number is generally NP-hard. However\, there is a simple (easy to compute) lower bound for the path number of a digraph in terms of its degree sequence\, and a conjecture of Alspach\, Pullman\, and Mason from 1976 states that this lower bound gives the correct value of the path number for any even tournament. The conjecture was recently resolved\, and in this talk I will discuss to what extent the conjecture holds for other digraphs. In particular I will discuss some of the ingredients of a recent result showing that the conjecture holds for almost all digraphs. \nMore generally we will see the conjecture holds with high probability for the random directed graph D_{n\,p} for a large range of p. In fact the proof does not use randomness in a significant way.\n\nThis is joint work with Alberto Espuny Díaz and Fabian Stroh. \nJoin Zoom Meeting: link
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-viresh-patel-university-of-amsterdam/
LOCATION:Zoom seminar
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="Jason Brown":MAILTO:jason.brown@dal.ca
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=UTC:20211013T153000
DTEND;TZID=UTC:20211013T163000
DTSTAMP:20260611T004152
CREATED:20211012T120433Z
LAST-MODIFIED:20211012T120607Z
UID:6327-1634139000-1634142600@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar: Danny Dyer (Memorial University)
DESCRIPTION:Title: The basics of the deduction game \nAbstract: \nThe deduction game is a new variant of the classical chasers and runners game where the chasers are trying to catch an invisible runner quickly\, but with no communication possible between chasers on different vertices. Instead\, chasers may deduce where their fellow chasers *must* move\, and make corresponding adjustments to their own movements. The goal is to use as few chasers as possible\, and in some cases that number is quite high. We will examine some bounds on the deduction number\, determine the deduction number of several classes of graphs\, and pose some open problems. This is joint work with Andrea Burgess and Mozhgan Farahani. \nJoin Zoom Meeting 
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-danny-dyer-memorial-university/
LOCATION:Zoom seminar
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="Jason Brown":MAILTO:jason.brown@dal.ca
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BEGIN:VEVENT
DTSTART;TZID=UTC:20211006T153000
DTEND;TZID=UTC:20211006T163000
DTSTAMP:20260611T004152
CREATED:20211004T174543Z
LAST-MODIFIED:20211004T174543Z
UID:6322-1633534200-1633537800@aarms.math.ca
SUMMARY:Atlantic Graph Theory Seminar: Anthony Bonato (Ryerson University)
DESCRIPTION:In pursuit-evasion games\, a set of pursuers attempts to locate\, eliminate\, or contain an evader in a network. The rules\, specified from the outset\, greatly determine the difficulty of the questions posed above. For example\, the evader may be visible\, but the pursuers may have limited movement speed\, only moving to nearby vertices adjacent to them. \nCentral to pursuit-evasion games is the idea of optimizing certain parameters\, whether they are the search number\, burning number\, or localization number\, for example. We report on progress in several pursuit-evasion games on graphs and conjectures arising from their analysis. Finding the values\, bounds\, and algorithms to compute these graph parameters leads to topics intersecting graph theory\, the probabilistic method\, and geometry.
URL:https://aarms.math.ca/event/atlantic-graph-theory-seminar-anthony-bonato-ryerson-university/
LOCATION:Zoom seminar
CATEGORIES:AARMS Atlantic Graph Theory Seminar
ORGANIZER;CN="Jason Brown":MAILTO:jason.brown@dal.ca
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