CanaDAM 2021
En ligne, 25 - 28 mai 2021 canadam.math.ca/2021f
Programme        

Horaire - Minisymposia libres

Veuillez noter que l'horaire peut être modifié sans préavis, surtout s'il s'agit de modifications à l'intérieur d'une session. Les horaires sont en HAE (GMT -4)

Algebraic and Combinatorial Approaches to Designs and Codes - Part I (CM1)
Org: Thaís Bardini Idalino (Universidade Federal de Santa Catarina, Brazil), Jonathan Jedwab (Simon Fraser University) et Shuxing Li (Simon Fraser University)
Designs and codes are closely intertwined studies that share many common discrete structures. This minisymposium explores algebraic and combinatorial approaches to the construction, analysis, and classification of designs and codes, with particular emphasis on these common discrete structures.
 
mardi 25 mai
11:20 - 11:45 Jingzhou Na (Simon Fraser University), Perfect Sequence Covering Arrays
11:50 - 12:15 Karen Meagher (University of Regina), Erd\H{o}s-Ko-Rado theorems for 2-transitive groups
12:20 - 12:45 Andriaherimanana Razafimahatratra (University of Regina), On transitive groups that do not have the Erdős-Ko-Rado property
12:50 - 13:15 Aidan W. Murphy (Virginia Tech, VA), Codes from curves and repair
13:20 - 13:45 Bill Martin (Worcester Polytechnic Institute, MA), Selecting resilient functions for fault-tolerant random bit generation
 
Algebraic and Combinatorial Approaches to Designs and Codes - Part II (CM7)
Org: Thaís Bardini Idalino (Universidade Federal de Santa Catarina, Brazil), Jonathan Jedwab (Simon Fraser University) et Shuxing Li (Simon Fraser University)
Designs and codes are closely intertwined studies that share many common discrete structures. This minisymposium explores algebraic and combinatorial approaches to the construction, analysis, and classification of designs and codes, with particular emphasis on these common discrete structures.
 
mardi 25 mai
15:30 - 15:55 Hadi Kharaghani (University of Lethbridge), A class of balanced weighing matrices and the corresponding association scheme
16:00 - 16:25 Jim Davis (University of Richmond, VA), Designs with the Symmetric Difference Property
16:30 - 16:55 Zeying Wang (Michigan Technological University, MI), New necessary conditions on (negative) Latin square type partial difference sets in abelian groups
17:00 - 17:25 Ian Wanless (Monash University, Australia), Omniversal Latin squares
17:30 - 17:55 Xiande Zhang (University of Science and Technology of China), Optimal ternary constant weight codes in $l_1$-metric
 
Algebraic and Combinatorial Approaches to Designs and Codes - Part III (CM12)
Org: Thaís Bardini Idalino (Universidade Federal de Santa Catarina, Brazil), Jonathan Jedwab (Simon Fraser University) et Shuxing Li (Simon Fraser University)
Designs and codes are closely intertwined studies that share many common discrete structures. This minisymposium explores algebraic and combinatorial approaches to the construction, analysis, and classification of designs and codes, with particular emphasis on these common discrete structures.
 
mercredi 26 mai
11:20 - 11:45 Marco Buratti (University of Perugia, Italy), Old and new results on elementary abelian 2-designs
11:50 - 12:15 Nikolay Kaleyski (University of Bergen, Norway), Bounding the Hamming distance between APN functions
12:20 - 12:45 Eimear Byrne (University College Dublin, Ireland), New subspace designs from $q$-matroids
12:50 - 13:15 Gohar Kyureghyan (University of Rostock, Germany), Image sets of APN maps
13:20 - 13:45 Alex Pott (Otto-von-Guericke University, Germany), Designs and bent functions
 
Algorithms for interval graphs and related families - Part I (CM26)
Org: Yixin Cao (Hong Kong Polytechnic University) et Derek G. Corneil (University of Toronto)
Interval graphs are intersection graphs of intervals on the real line. For their natural applications (e.g., representation of temporal objects) and nice mathematical properties, interval graphs have been among the most studied in algorithmic graph theory. The study of these families have brought forth new techniques as well as new structures. Their popularity also benefits from many interesting kins, e.g., circular-arc graphs, interval bigraphs, and circular-ones matrices, not to mention chordal graphs, AT-free graphs and many subclasses. On the one hand, even the recognition of interval graphs, for which a linear-time algorithm has been presented nearly 50 years ago, is still under intensive investigation. On the other hand, there are recently a lot of exciting new results on problems formulated on these families. We plan to bring together experts in graph theory and in algorithms to explore the properties and algorithms of these families.
 
vendredi 28 mai
11:20 - 11:45 Derek G. Corneil (University of Toronto), Early days of interval graph algorithms
11:50 - 12:15 Akanksha Agrawal (Indian Institute of Technology Madras), Polynomial Kernel for Interval Vertex Deletion
12:20 - 12:45 Guillaume Ducoffe (University of Bucharest, Romania), Faster computation of graph diameter by using one (or two) properties of the interval graphs
12:50 - 13:15 Francisco Soulignac (University of Buenos Aires), Representation problems for unit interval and unit circular-arc graphs
13:20 - 13:45 Flavia Bonomo (University of Buenos Aires), Algorithms for k-thin and proper k-thin graphs
 
Algorithms for interval graphs and related families - Part II (CM32)
Org: Yixin Cao (Hong Kong Polytechnic University) et Derek G. Corneil (University of Toronto)
Interval graphs are intersection graphs of intervals on the real line. For their natural applications (e.g., representation of temporal objects) and nice mathematical properties, interval graphs have been among the most studied in algorithmic graph theory. The study of these families have brought forth new techniques as well as new structures. Their popularity also benefits from many interesting kins, e.g., circular-arc graphs, interval bigraphs, and circular-ones matrices, not to mention chordal graphs, AT-free graphs and many subclasses. On the one hand, even the recognition of interval graphs, for which a linear-time algorithm has been presented nearly 50 years ago, is still under intensive investigation. On the other hand, there are recently a lot of exciting new results on problems formulated on these families. We plan to bring together experts in graph theory and in algorithms to explore the properties and algorithms of these families.
 
vendredi 28 mai
15:30 - 15:55 Yixin Cao (Hong Kong Polytechnic University), Recognizing (unit) interval graphs by zigzag graph searches
16:00 - 16:25 Celina de Figueiredo (Universidade Federal do Rio de Janeiro), Maximum cut and Steiner tree restricted to interval graphs and related families
16:30 - 16:55 Pavol Hell (Simon Fraser University), Variants of interval graphs and related families
17:00 - 17:25 Michel Habib (Paris University), Grounded intersection graphs and forbidden patterns on 4 vertices
17:30 - 17:55 Lalla Mouatadid (University of Toronto and Google), $(\alpha, \beta)$-Modules in Graphs
 
Arithmetic Combinatorics - Part I (CM2)
Org: Yifan Jing (University of Illinois at Urbana-Champaign) et Chieu-Minh Tran (University of Notre Dame)
Arithmetic Combinatorics is a rapidly growing discipline, with interactions with many other areas of mathematics, including ergodic theory, harmonic analysis, number theory, model theory, etc.

In this mini-symposium, we aim to bring researchers in arithmetic combinatorics in order to present recent developments in this field, exchange research ideas, and initiate new collaborations.

 
mardi 25 mai
11:20 - 11:45 Sarah Peluse (Institute for Advanced Study), An asymptotic version of the prime power conjecture for perfect difference sets
11:50 - 12:15 George Shakan (University of Oxford), Effective Khovanskii Theorems
12:20 - 12:45 Max Wenqiang Xu (Stanford University), Discrepancy in Modular Arithmetic Progressions
12:50 - 13:15 Cosmin Pohoata (Yale University), Trifference problem
13:20 - 13:45 Yifan Jing (University of Illinois at Urbana-Champaign), Minimal and nearly minimal measure expansions in connected unimodular groups
 
Arithmetic Combinatorics - Part II (CM13)
Org: Yifan Jing (University of Illinois at Urbana-Champaign) et Chieu-Minh Tran (University of Notre Dame)
Arithmetic Combinatorics is a rapidly growing discipline, with interactions with many other areas of mathematics, including ergodic theory, harmonic analysis, number theory, model theory, etc.

In this mini-symposium, we aim to bring researchers in arithmetic combinatorics in order to present recent developments in this field, exchange research ideas, and initiate new collaborations.

 
mercredi 26 mai
11:20 - 11:45 Weikun He (Korea Institute for Advanced Study), Sum-product estimates in semisimple algebras and random walks on the torus
11:50 - 12:15 Simon Machado (University of Cambridge), Approximate Subgroups, Meyer Sets and Arithmeticity
12:20 - 12:45 Arturo Rodriguez Fanlo (University of Oxford), On metric approximate subgroups
12:50 - 13:15 Gabriel Conant (University of Cambridge), Quantitative stable arithmetic regularity in arbitrary finite groups
13:20 - 13:45 Chieu-Minh Tran (University of Notre Dame), A nonabelian Brunn-Minkowski inequality
 
Average Graph Parameters - Part I (CM16)
Org: Stijn Cambie (Radboud University Nijmegen, the Netherlands)
Continuing the sessions held last year, we want to get together with enthusiasts working on different average graph parameters. From the minisymposium in 2019 arised some papers, so we are hopeful for this year as well. During the talks, the state of the art and intriguing open problems in the field will be shared.

Starting with the oldest and most well-known average graph parameter, the Wiener index (which dates back to 1947) or equivalently the average distance of a graph. But there will also be talks on the average connectivity, order and size of certain substructures of graphs such as independent sets, dominating sets and subtrees.

 
mercredi 26 mai
15:30 - 15:55 Peter Dankelmann (University of Johannesburg), On the Wiener Index of Graphs with Large Maximum Degree
16:00 - 16:25 Riste Skrekovski (University of Ljubljana), Some problems and results on some graph parameters
16:30 - 16:55 Eva Czabarka (University of South Carolina), Minimum Wiener index of planar triangulations and quadrangulations
17:00 - 17:25 Fadekemi Janet Osaye (Auburn University), The average eccentricity of a graph with prescribed girth
17:30 - 17:55 Lucas Mol (The University of Winnipeg), The mean subtree order of graphs under edge addition
 
Average Graph Parameters - Part II (CM33)
Org: Stijn Cambie (Radboud University Nijmegen, the Netherlands)
Continuing the sessions held last year, we want to get together with enthusiasts working on different average graph parameters. From the minisymposium in 2019 arised some papers, so we are hopeful for this year as well. During the talks, the state of the art and intriguing open problems in the field will be shared.

Starting with the oldest and most well-known average graph parameter, the Wiener index (which dates back to 1947) or equivalently the average distance of a graph. But there will also be talks on the average connectivity, order and size of certain substructures of graphs such as independent sets, dominating sets and subtrees.

 
vendredi 28 mai
15:30 - 15:55 Iain Beaton (Dalhousie University), The Average Order of Dominating Sets of a Graph
16:00 - 16:25 Valisoa Misanantenaina (Stellenbosch University), The average size of independent vertex/edge sets of a graph
16:30 - 16:55 Andrew Vince (University of Florida), The Average Size of a Connected Vertex Set of a Graph
17:00 - 17:25 John Haslegrave (University of Warwick), The average size of a connected set in a connected graph with degree constraints
17:30 - 17:55 Suil O (The State University of New York, Korea), The average connectivity matrix of a graph
 
Chemical Graph Theory - Part I (CM3)
Org: Nino Bašić (University of Primorska, Slovenia) et Elizabeth Hartung (Massachusetts College of Liberal Arts, USA)
This minisymposium in chemical graph theory explores various applications of graph theory to chemistry. A molecule can be described as a graph, where vertices represent atoms and edges represent chemical bonds: benzenoids and fullerenes are two examples of such graph classes. Properties of those graphs, such as perfect matchings and graph spectra, can be used to model characteristics of molecules, including stability, reactivity, and electronic structure. Other related topics in chemical graph theory include enumeration of graphs classes and algorithms for their enumeration. Graphs are also important for biosciences, such as phylogenetics where they are used to study phylogenetic trees and related structures, and synthetic biology where graphs proved to be useful for modeling self-assembly of DNA and protein nanostructures.
 
mardi 25 mai
11:20 - 11:45 Elizabeth Hartung (Massachusetts College of Liberal Arts, USA), Resonance Structures and Aromaticity in Capped Carbon Nanotubes
11:50 - 12:15 Jack Graver (Syracuse University, USA), The Clar - Fries Mystery
12:20 - 12:45 Petra Žigert Pleteršek (University of Maribor, Slovenia), Topological indices of unsaturated hydrocarbons
12:50 - 13:15 Dong Ye (Middle Tennessee State University, USA), Resonance graphs on perfect matchings
13:20 - 13:45 Vesna Andova (Ss. Cyril and Methodius University, Northern Macedonia), On Three Constructions of Nanotori
 
Chemical Graph Theory - Part II (CM8)
Org: Nino Bašić (University of Primorska, Slovenia) et Elizabeth Hartung (Massachusetts College of Liberal Arts, USA)
This minisymposium in chemical graph theory explores various applications of graph theory to chemistry. A molecule can be described as a graph, where vertices represent atoms and edges represent chemical bonds: benzenoids and fullerenes are two examples of such graph classes. Properties of those graphs, such as perfect matchings and graph spectra, can be used to model characteristics of molecules, including stability, reactivity, and electronic structure. Other related topics in chemical graph theory include enumeration of graphs classes and algorithms for their enumeration. Graphs are also important for biosciences, such as phylogenetics where they are used to study phylogenetic trees and related structures, and synthetic biology where graphs proved to be useful for modeling self-assembly of DNA and protein nanostructures.
 
mardi 25 mai
15:30 - 15:55 Patrick W. Fowler (University of Sheffield, UK), The Chemical Significance of Graph Energy
16:00 - 16:25 Dragan Stevanović (Mathematical Institute of the Serbian Academy of Sciences and Arts, Serbia), On Hosoya's dormants and sprouts
16:30 - 16:55 Irene Sciriha (University of Malta, Malta), The conductivity of the connected sum of root graphs with a common nullspace
17:00 - 17:25 Riste Škrekovski (University of Ljubljana, Slovenia), On 12-regular nut graphs
17:30 - 17:55 Jelena Sedlar (University of Split, Croatia), Two types of indices and their extremal trees
 
Chemical Graph Theory - Part III (CM14)
Org: Nino Bašić (University of Primorska, Slovenia) et Elizabeth Hartung (Massachusetts College of Liberal Arts, USA)
This minisymposium in chemical graph theory explores various applications of graph theory to chemistry. A molecule can be described as a graph, where vertices represent atoms and edges represent chemical bonds: benzenoids and fullerenes are two examples of such graph classes. Properties of those graphs, such as perfect matchings and graph spectra, can be used to model characteristics of molecules, including stability, reactivity, and electronic structure. Other related topics in chemical graph theory include enumeration of graphs classes and algorithms for their enumeration. Graphs are also important for biosciences, such as phylogenetics where they are used to study phylogenetic trees and related structures, and synthetic biology where graphs proved to be useful for modeling self-assembly of DNA and protein nanostructures.
 
mercredi 26 mai
11:20 - 11:45 Tomaž Pisanski (University of Ljubljana, Slovenia), Flat benzenoid complexes
11:50 - 12:15 Tomislav Došlić (University of Zagreb, Croatia), Nice subgraphs of fullerene graphs with prescribed components
12:20 - 12:45 Damir Vukičević (University of Split, Croatia), Vukicevic, Boskovic: Adriatic graphs - mathematical properties and applications to correct NIST database
12:50 - 13:15 Lavanya Selvaganesh (Indian Institute of Technology (BHU), India), Bounds Of The Symmetric Division Deg Index For Graphs With Cyclomatic Number At Most 2 And With A Perfect Matching
13:20 - 13:45 Nino Bašić (University of Primorska, Slovenia), Pentagonal Clusters in Fullerenes
 
Coherent configurations with few fibers - Part I (CM19)
Org: Alyssa Sankey (University of New Brunswick)
Coherent configurations are sets of association schemes, linked by additional relations. They arise naturally in relation to the graph isomorphism problem and to finite permutation groups, which provide numerous examples of Schurian cc's -- those in which the orbits, under the action of the group on ordered pairs, form the relations. The fruitful and interesting interplay between graphs, designs, finite geometries and other combinatorial objects is apparent in many constructions of both Schurian and non-Schurian cc's. Some headway has been made in recent work employing computer experimentation to construct and enumerate small cc's. The cc's with very few vertices have been catalogued, yet the classification of cc's with few fibers has not been approached in a systematic way. This minisymposium highlights work towards that goal.
 
jeudi 27 mai
11:20 - 11:45 Stefan Gyurki (Slovak University of Technology), The Paulus-Rozenfeld-Thompson graph on 26 vertices
11:50 - 12:15 Bohdan Kivva (University of Chicago), Robustness of the Johnson scheme under fusion and extension
12:20 - 12:45 Mikhail Muzychuk (Ben-Gurion University of the Negev), On Jordan schemes
12:50 - 13:15 Grigory Ryabov (Novosibirsk State University), Infinite family of nonschurian separable association schemes
 
Coherent configurations with few fibers - Part II (CM22)
Org: Alyssa Sankey (University of New Brunswick)
Coherent configurations are sets of association schemes, linked by additional relations. They arise naturally in relation to the graph isomorphism problem and to finite permutation groups, which provide numerous examples of Schurian cc's -- those in which the orbits, under the action of the group on ordered pairs, form the relations. The fruitful and interesting interplay between graphs, designs, finite geometries and other combinatorial objects is apparent in many constructions of both Schurian and non-Schurian cc's. Some headway has been made in recent work employing computer experimentation to construct and enumerate small cc's. The cc's with very few vertices have been catalogued, yet the classification of cc's with few fibers has not been approached in a systematic way. This minisymposium highlights work towards that goal.
 
jeudi 27 mai
15:30 - 15:55 Dennis Epple (University of Toronto), The Shrikhande Graph on the Crossroads of Algebraic and Topological Graph Theory
16:00 - 16:25 Sven Reichard (Dresden International University), On Jordan Schemes II
16:30 - 16:55 Alyssa Sankey (University of New Brunswick), Strongly regular designs admitting fusion to strongly regular decomposition
17:00 - 17:25 Jason Williford (University of Wyoming), Coherent Configurations and Extremal Graph Theory
 
Computational proof techniques for combinatorics on words (CM4)
Org: James Currie (University of Winnipeg), Narad Rampersad (University of Winnipeg) et Jeffrey Shallit (University of Waterloo)
Combinatorics on words is an old area that studies the properties of words (finite strings of symbols over a finite alphabet), but one where the available techniques have recently been supplemented by the use of various computational ideas, such as decision algorithms, SAT solvers, and proof assistants. With these techniques, proofs of conjectures can sometimes be obtained purely mechanically, with little work by humans. This mini-symposium will feature introductory talks on these ideas, illustrated by many examples.
 
mardi 25 mai
11:20 - 11:45 Curtis Bright (University of Windsor), SAT solvers and combinatorics problems
11:50 - 12:15 Joel D. Day (Loughborough University), Computational methods for solving word equations
12:20 - 12:45 Stepan Holub (Charles University, Prague), Proof assistants in combinatorics on words
12:50 - 13:15 Jeffrey Shallit (University of Waterloo), Proving theorems in combinatorics on words with Walnut
13:20 - 13:45 Reed Oei (University of Illinois), Design and use of the Pecan system
 
Cycles in Planar Graphs (CM9)
Org: Abhinav Shantanam (Simon Fraser University) et Carol T. Zamfirescu (Ghent University)
The talks focus on recent developments concerning cycles in planar graphs -- fundamental topics in graph theory -- with an emphasis on longest cycles and Hamiltonicity.
 
mardi 25 mai
15:30 - 15:55 Xiaonan Liu (Georgia Institute of Technology), Number of Hamiltonian cycles in planar triangulations
16:00 - 16:25 On-Hei Solomon Lo (University of Science and Technology of China), Gaps in the cycle spectrum of polyhedral graphs
16:30 - 16:55 Emily A. Marshall (Arcadia University), Hamiltonicity of planar graphs with a forbidden minor
17:00 - 17:25 Jens M. Schmidt (Hamburg University of Technology), The Isolation Lemma
17:30 - 17:55 Abhinav Shantanam (Simon Fraser University), Pancyclicity in $4$-connected planar graphs
 
Enumerative and Extremal Graph Theory (CM34)
Org: Rachel Kirsch (Iowa State University)
This minisymposium will highlight recent advances in graph theory, hypergraph theory, and combinatorics, with an emphasis on problems involving counting or optimizing some parameter.
 
vendredi 28 mai
15:30 - 15:55 Gabriela Araujo-Pardo (Universidad Nacional Autónoma de México), The Moore and Cage Problems on Mixed Graphs
16:00 - 16:25 Zhanar Berikkyzy (Fairfield University), Rainbow solutions to the Sidon equation in cyclic groups and in the interval
16:30 - 16:55 Jessica De Silva (California State University Stanislaus), Image Segmentation via Hypergraph-based MRF Models
17:00 - 17:25 Michael Guyer (Auburn University), On clique immersions in line graphs
17:30 - 17:55 Linda Lesniak (Western Michigan University), On the necessity of Chv\'{a}tal's hamiltonian degree condition
 
Extremal problems for hypergraphs (CM5)
Org: Frederik Garbe (Masaryk University)
Compared to the graph case, extremal problems in the context of hypergraphs often exhibit an additionally nuanced behaviour. This minisymposium covers a wide range of recent results from this area - including hypergraph Turán numbers, Dirac-type results, and hypergraph colouring problems.
 
mardi 25 mai
11:20 - 11:45 Stefan Glock (ETH Zürich), The intersection spectrum of 3-chromatic intersecting hypergraphs
11:50 - 12:15 Tom Kelly (University of Birmingham), A proof of the Erdős–Faber–Lovász conjecture
12:20 - 12:45 Ander Lamaison (Masaryk University), Hypergraphs with minimum uniform Turán density
12:50 - 13:15 Richard Lang (Heidelberg University), Minimum degree conditions for tight Hamilton cycles
13:20 - 13:45 Nicolás Sanhueza-Matamala (Czech Academy of Sciences), Spanning bounded-degree tight $k$-trees
 
Flow polytopes of graphs (CM27)
Org: Carolina Benedetti (Universidad de los Andes), Christopher Hanusa (Queens College of the City University of New York), Pamela E. Harris (Williams College) et Alejandro Morales (UMass, Amherst)
Flow polytopes of graphs are an important family of polytopes with connections to algebraic combinatorics, representation theory and optimization. There has been recent progress and connections of this class of polytopes with diagonal harmonics, Schubert polynomials, generalized permutahedra and Lorentzian polynomials. This minisymposium will bring together established and young researchers with closely related interests to share the latest results and open problems.
 
vendredi 28 mai
11:20 - 11:45 Jihyeug Jang (Sungkyunkwan University), Volumes of flow polytopes related to the caracol graphs
11:50 - 12:15 Karola Mészáros (Cornell University), Flow polytopes in combinatorics and algebra
12:20 - 12:45 Avery St. Dizier (University of Illinois, Urbana-Champaign), Flow Polytopes and Grothendieck polynomials
12:50 - 13:15 Emily Barnard (DePaul University), Pairwise Completability for 2-Simple Minded Collections
13:20 - 13:45 Martha Yip (University of Kentucky), A unifying framework for the $\nu$-Tamari lattice and principal order ideals in Young's lattice
 
Graph Colouring -- surfaces, homomorphisms, and distinguishing (CM28)
Org: Rick Brewster (Thompson Rivers University) et Benjamin Moore (University of Waterloo)
The study of colouring has deep roots in graph theory and remains a source of many interesting problems. In this collection of diverse speakers and talks, we visit both topological and algebraic questions. Two talks reach back to the 4 Colour Theorem with results on local choosability of planar graphs, and Grunbaum colourings. The other talks examine more algebraic questions. Two talks focus on homomorphisms, namely a density bound for triangle free 4-critical graphs and the circular chromatic number of signed graphs. While the remaining talk connects to automorphisms, namely, the distinguishing number of graphs.
 
vendredi 28 mai
11:20 - 11:45 Debra Boutin (Hamilton College), Distinguishing Cube Families
11:50 - 12:15 Zhouningxin Wang (IRIF, Universite de Paris), Circular chromatic number of signed graphs
12:20 - 12:45 Arnott Kidner (University of Victoria), Switchable 2-Colouring is Polynomial
12:50 - 13:15 Evelyne Smith-Roberge (University of Waterloo), Local choosability of planar graphs
13:20 - 13:45 Benjamin Moore (University of Waterloo), A density bound for triangle free 4-critical graphs
 
Graph Polynomials - Part I (CM17)
Org: Iain Beaton (Dalhousie University) et Ben Cameron (University of Guelph)
For a variety of combinatorial problems, such as network reliability and graph colourings, the models turn out to be graph polynomials. On the other hand, the investigation of various subgraph properties leads one to explore the associated combinatorial sequences by formulating generating polynomials. In all cases, polynomials carry useful information about the underlying combinatorics, and one can draw on classical areas of mathematics, such as analysis and algebra, in the investigations. Combinatorial properties such as unimodality and log-concavity of various graphical sequences can surprisingly be extracted from the location of the roots of such polynomials. In this two part minisymposium, we aim to draw on the research of people working on a variety of graph polynomials to share techniques and methods to help advance the study of each polynomial.
 
mercredi 26 mai
15:30 - 15:55 Iain Beaton (Dalhousie University), On the Unimodality of Domination Polynomials
16:00 - 16:25 Danielle Cox (Mount Saint Vincent University), Chromatic Polynomials of 2-Edge-Coloured Graphs
16:30 - 16:55 Samantha Dahlberg (Arizona State University), Chromatic symmetric functions and $e$-positivity
17:00 - 17:25 David Galvin (University of Notre Dame), The independence polynomial of the random tree
17:30 - 17:55 János Makowsky (Technion - Israel Institute of Technology), Graph polynomials unimodular for almost all graphs.
 
Graph Polynomials - Part II (CM23)
Org: Iain Beaton (Dalhousie University) et Ben Cameron (University of Guelph)
For a variety of combinatorial problems, such as network reliability and graph colourings, the models turn out to be graph polynomials. On the other hand, the investigation of various subgraph properties leads one to explore the associated combinatorial sequences by formulating generating polynomials. In all cases, polynomials carry useful information about the underlying combinatorics, and one can draw on classical areas of mathematics, such as analysis and algebra, in the investigations. Combinatorial properties such as unimodality and log-concavity of various graphical sequences can surprisingly be extracted from the location of the roots of such polynomials. In this two part minisymposium, we aim to draw on the research of people working on a variety of graph polynomials to share techniques and methods to help advance the study of each polynomial.
 
jeudi 27 mai
15:30 - 15:55 Ferenc Bencs (Alfréd Rényi Institute of Mathematics), Zero-free regions for some graph polynomials.
16:00 - 16:25 Jason Brown (Dalhousie University), Recent Results in Network Reliability
16:30 - 16:55 Ben Cameron (University of Guelph), The largest real root of the independence polynomial of a unicyclic graph
17:00 - 17:25 Péter Csikvári (Eötvös Loránd University), Evaluations of Tutte polynomials of large girth regular graphs
17:30 - 17:55 Stephan Wagner (Uppsala University), Distribution of the coefficients of the subtree polynomial
 
Graph Product Structure Theory (CM10)
Org: Pat Morin (Carleton University)
Dujmović, Joret, Micek, Morin, Ueckerdt and Wood (2019) showed that every planar graph is contained in the strong product of a bounded treewidth graph and a path. This mini-symposium will first introduce this \emph{product structure theorem} and its generalizations and present a number of applications, including new asymptotically optimal results for

  • queue number (Heath, Leighton, Rosenberg 1992);
  • nonrepetitive chromatic number (Alon, Grytczuk, Hałuszczak, and Riordan 2002);
  • $p$-centered colourings (Nešetřil and Ossona de Mendez 2006, Dvořák 2016) and $\ell$-vertex rankings (Karpas, Neiman, and Smorodinsky 2016); and
  • adjacency labelling and universal graphs (Kannan, Naor, and Rudich 1988; Babai, Erd\H{o}s, Chung, Graham, and Spencer 1982).
The introductory talk will also discuss several generalization of the product structure theorem that extend these applications to broader graph classes, including bounded genus graphs, apex-minor-free graphs, bounded-degree graphs from minor-closed families, and $k$-planar graphs for fixed $k$.
 
mardi 25 mai
15:30 - 15:55 Vida Dujmovic (University of Ottawa), Product structure Theorem(s)
16:00 - 16:25 David Wood (Monash University), Planar graphs have bounded queue-number
16:30 - 16:55 Louis Esperet (Laboratoire G-SCOP (CNRS, Univ. Grenoble Alpes)), Planar graphs have bounded nonrepetitive chromatic number
17:00 - 17:25 Piotr Micek (Jagiellonian University), Centered colorings and vertex rankings
17:30 - 17:55 Gwenaël Joret (Université Libre de Bruxelles), Sparse universal graphs for planarity
 
Graph Searching (CM6)
Org: Anthony Bonato (Ryerson University) et Nancy Clarke (Acadia University)
In graph searching, a set of pursuers attempts to locate or eliminate the threat posed by an evader in the network. The rules 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. Such a paradigm leads to the game of Cops and Robbers, and deep questions like Meyniel's conjecture on the cop number of a graph. Central to all graph searching questions is the idea of optimizing certain parameters, whether they are the cop number, burning number, or localization number, for example. Finding the exact values, bounds, and algorithms to compute these graph parameters leads to fascinating topics intersecting with classical graph theory, combinatorial designs, and probabilistic methods.

The proposed minisymposium brings together leading researchers in graph searching, who will present state-of-the-art research in this direction.

 
mardi 25 mai
11:20 - 11:45 Fionn Mc Inerney (CISPA Helmholtz Center for Information Security), Eternal Domination in D-Dimensional Grids
11:50 - 12:15 Bojan Mohar (Simon Fraser University), Cops and robbers on surfaces
12:20 - 12:45 Nancy Clarke (Acadia University), A variation of the Cops and Robber game with a new capture condition
12:50 - 13:15 William Kinnersley (University of Rhode Island), Infinitely fast robbers on grids
13:20 - 13:45 Melissa Huggan (Ryerson University), Locating an invisible adversary
 
Movement and symmetry in graphs - Part I (CM11)
Org: Karen Gunderson (University of Manitoba), Karen Meagher (University of Regina) et Joy Morris (University of Lethbridge)
In algebraic graph theory, combinatorial matrix theory, infection processes on graphs, and extremal combinatorics, the best modern results are often found using an interdisciplinary approach, leveraging tools and techniques from these other fields. The tools developed in solving these types of problems are often strong and transferable. Algebraic techniques, a deeper understanding of graph symmetries, probabilistic techniques and structural extremal results show a great promise to develop a deep and general theory that encompasses many graph and hypergraph classes all at once.

This minisymposium will be highlighting recent results in these areas that connect to the planned research topics and projects for the PIMS-funded CRG ``Movement and symmetry in graphs''.

 
mardi 25 mai
15:30 - 15:55 Karen Gunderson (University of Manitoba), Bootstrap percolation on infinite graphs
16:00 - 16:25 Jeannette Janssen (Dalhousie University), An approximation algorithm for finding the zero-forcing number of a graph
16:30 - 16:55 Karen Meagher (University of Regina), Open problems related to Erd\H{o}s-Ko-Rado type results
17:00 - 17:25 Joy Morris (University of Lethbridge), Regular Representations
 
Movement and symmetry in graphs - Part II (CM29)
Org: Karen Gunderson (University of Manitoba), Karen Meagher (University of Regina) et Joy Morris (University of Lethbridge)
In algebraic graph theory, combinatorial matrix theory, infection processes on graphs, and extremal combinatorics, the best modern results are often found using an interdisciplinary approach, leveraging tools and techniques from these other fields. The tools developed in solving these types of problems are often strong and transferable. Algebraic techniques, a deeper understanding of graph symmetries, probabilistic techniques and structural extremal results show a great promise to develop a deep and general theory that encompasses many graph and hypergraph classes all at once.

This minisymposium will be highlighting recent results in these areas that connect to the planned research topics and projects for the PIMS-funded CRG ``Movement and symmetry in graphs''.

 
vendredi 28 mai
11:20 - 11:45 Edward Dobson (University of Primorska), Recognizing vertex-transitive digraphs which are wreath products and double coset digraphs
11:50 - 12:15 Venkata Raghu Tej Pantangi (Southern University of Science and Technology), Intersecting sets in Permutation groups.
12:20 - 12:45 Jason Semeraro (University of Leicester), Higher tournaments, hypergraphs, automorphisms and extremal results
12:50 - 13:15 Mahsa Nasrollahi (University of Regina), On a generalization of the Erdos-Ko-Rado theorem to intersecting and set-wise intersecting perfect matchings
13:20 - 13:45 Gabriel Verret (University of Auckland), Regular Cayley maps and skew morphisms of monolithic groups
 
New Trends in Analytic Combinatorics (CM24)
Org: Stephen Melczer (University of Waterloo)
The use of analytic methods to derive asymptotic behaviour of combinatorial sequences is a cornerstone of modern enumeration. This minisymposium aims to highlight new research directions in the area, including tools for multivariate generating functions, sequences with "exotic" asymptotic behaviour, generating function classes beyond the common D-finite framework, and an entropy approach to asymptotics; applications include topics in theoretical computer science, representation theory, and algebraic combinatorics. By combining both theory and practice, and focusing on current research, the session aims to strengthen old collaborations and foster new ones.
 
jeudi 27 mai
15:30 - 15:55 Michael Wallner (TU Wein), Compacted binary trees and minimal automata admit stretched exponentials
16:00 - 16:25 Veronika Pillwein (RISC - Johannes Kepler University), Algorithms beyond the holonomic universe
16:30 - 16:55 Stephen Gillen (University of Pennsylvania), Gillis-Reznick-Zeilberger's power series and the mysterious factor of 3
17:00 - 17:25 Greta Panova (University of Southern California), Unimodality and Kronecker asymptotics via random variables
17:30 - 17:55 Marcus Michelen (University of Illinois at Chicago), Maximum entropy and integer partitions
 
Practical Applications of Design Theory - Part I (CM30)
Org: Thaís Bardini Idalino (Universidade Federal de Santa Catarina, Brazil), Jonathan Jedwab (Simon Fraser University) et Shuxing Li (Simon Fraser University)
Practical questions about how to design experiments were the historical inspiration for the rich and beautiful study of modern design theory, which has deep connections to coding theory, finite geometry, graph theory, and other branches of combinatorics. This minisymposium showcases the fruitful interplay between theory and application, by exploring some of the diverse ways in which design theory continues to be used in practical applications.
 
vendredi 28 mai
11:20 - 11:45 Yasmeen Akhtar (IISER Pune, India), Level-wise Screening via Locating Arrays
11:50 - 12:15 Lucia Moura (University of Ottawa), Variable-strength arrays and applications
12:20 - 12:45 Maura Paterson (Birkbeck, University of London), Authentication codes with perfect secrecy and algebraic manipulation detection codes
12:50 - 13:15 Brett Stevens (Carleton University), Single change covering designs
13:20 - 13:45 Doug Stinson (University of Waterloo), On equitably ordered splitting BIBDs
 
Practical Applications of Design Theory - Part II (CM35)
Org: Thaís Bardini Idalino (Universidade Federal de Santa Catarina, Brazil), Jonathan Jedwab (Simon Fraser University) et Shuxing Li (Simon Fraser University)
Practical questions about how to design experiments were the historical inspiration for the rich and beautiful study of modern design theory, which has deep connections to coding theory, finite geometry, graph theory, and other branches of combinatorics. This minisymposium showcases the fruitful interplay between theory and application, by exploring some of the diverse ways in which design theory continues to be used in practical applications.
 
vendredi 28 mai
15:30 - 15:55 Charlie Colbourn (Arizona State University), Popularity Block Ordering for Steiner Systems
16:00 - 16:25 Peter Dukes (University of Victoria), The use of graph decompositions for variance-balanced designs in the presence of correlated errors
16:30 - 16:55 Guang Gong (University of Waterloo), Polynomials, Sequences and Complementary Codes
17:00 - 17:25 Kirsten Nelson (Carleton University), Construction of Covering Arrays from Interleaved Sequences
17:30 - 17:55 Daniel Panario (Carleton University), LDPC codes based on trade designs
 
Recent aspects of sphere packings - Part I (CM18)
Org: Karoly Bezdek (University of Calgary, Canada) et Oleg Musin (The University of Texas Rio Grande Valley, USA)
Sphere packings have been studied from the birth of geometry. The minisymposium will focus on selected latest developments about densest packings of spheres and extremal properties of contact graphs of sphere packings. Particular emphases are given for estimating kissing numbers and contact numbers of congruent sphere packings in Euclidean as well as non-Euclidean spaces. The methods to be discussed use techniques from combinatorial geometry, convex geometry; geometry of numbers; Voronoi tilings; geometric rigidity; coding theory; linear programming as well as semidefinite programming. Together with the latest results we hope to discuss some open problems that appear to be within reach and have the potential to progress the interplay between analysis, geometry, and combinatorics. Part I will have 5 talks each being centered around kissing numbers. Part II will consist of 5 talks investigating densest sphere packings and contact graphs of sphere packings.
 
mercredi 26 mai
15:30 - 15:55 Serge Vladut (Aix-Marseille University, France), Lattices with exponentially large kissing numbers
16:00 - 16:25 Alexander Kolpakov (University of Neuchatel, Neuchatel, Switzerland), Kissing number in non-Euclidean spaces of constant sectional curvature
16:30 - 16:55 Maria Dostert (Royal Institute of Technology (KTH), Stockholm, Sweden), Kissing number of the hemisphere in dimension 8
17:00 - 17:25 Alexey Glazyrin (The University of Texas Rio Grande Valley, USA), Linear programming bounds revisited
17:30 - 17:55 Oleg Musin (The University of Texas Rio Grande Valley, USA), The SDP bound for spherical codes using their distance distribution
 
Recent aspects of sphere packings - Part II (CM25)
Org: Karoly Bezdek (University of Calgary, Canada) et Oleg Musin (The University of Texas Rio Grande Valley, USA)
Sphere packings have been studied from the birth of geometry. The minisymposium will focus on selected latest developments about densest packings of spheres and extremal properties of contact graphs of sphere packings. Particular emphases are given for estimating kissing numbers and contact numbers of congruent sphere packings in Euclidean as well as non-Euclidean spaces. The methods to be discussed use techniques from combinatorial geometry, convex geometry; geometry of numbers; Voronoi tilings; geometric rigidity; coding theory; linear programming as well as semidefinite programming. Together with the latest results we hope to discuss some open problems that appear to be within reach and have the potential to progress the interplay between analysis, geometry, and combinatorics. Part I will have 5 talks each being centered around kissing numbers. Part II will consist of 5 talks investigating densest sphere packings and contact graphs of sphere packings.
 
jeudi 27 mai
15:30 - 15:55 Robert Connelly (Cornell University, Ithaca, NY, USA), Flipping and flowing
16:00 - 16:25 Thomas Fernique (University of Paris 13, Paris, France), Maximally dense sphere packings
16:30 - 16:55 Philippe Moustrou (UiT – The Arctic University of Norway, Norway), Coloring the Voronoi cell of a lattice
17:00 - 17:25 Dustin G. Mixon (The Ohio State University, Columbus, USA), Uniquely optimal codes of low complexity are symmetric
17:30 - 17:55 Karoly Bezdek (University of Calgary, Canada), Bounds for contact numbers of locally separable unit sphere packings
 
Spectral Graph Theory - Part I (CM20)
Org: Sebastian Cioaba (University of Delaware) et Michael Tait (Villanova University)
Spectral methods have become ubiquitous in graph theory for several reasons including efficiently giving bounds on hard to compute graph parameters (e.g. the Hoffman-ratio bound), quantifying edge distribution and pseudo-randomness (e.g. the expander-mixing lemma and Cheeger-type inequalities), and giving well-performing graph algorithms (e.g. spectral partitioning and max-cut approximations). We propose a minisymposiumon "Spectral graph theory" focused on recent developments in the field. We propose a 2 part minisymposium with the following confirmed speakers:

Aida Abiad, Krystal Guo, Ferdinand Ihringer, Jephian Lin, Nathan Lindzey, Theo McKenzie, Siddanth Mohanty, Sjanne Zeijlemaker

 
jeudi 27 mai
11:20 - 11:45 Ferdinand Ihringer (Ghent University), Strongly regular graphs satisfying the $4$-vertex condition
11:50 - 12:15 Jephian Lin (National Sun Yat-sen University), The strong spectral property for graphs
12:20 - 12:45 Aida Abiad (Eindhoven University of Technology), Neumaier graphs with few eigenvalues
12:50 - 13:15 Krystal Guo (University of Amsterdam), Entanglement of free Fermions on distance-regular graphs
 
Spectral Graph Theory - Part II (CM31)
Org: Sebastian Cioaba (University of Delaware) et Michael Tait (Villanova University)
Spectral methods have become ubiquitous in graph theory for several reasons including efficiently giving bounds on hard to compute graph parameters (e.g. the Hoffman-ratio bound), quantifying edge distribution and pseudo-randomness (e.g. the expander-mixing lemma and Cheeger-type inequalities), and giving well-performing graph algorithms (e.g. spectral partitioning and max-cut approximations). We propose a minisymposiumon "Spectral graph theory" focused on recent developments in the field. We propose a 2 part minisymposium with the following confirmed speakers:

Aida Abiad, Krystal Guo, Ferdinand Ihringer, Jephian Lin, Nathan Lindzey, Theo McKenzie, Siddanth Mohanty, Sjanne Zeijlemaker

 
vendredi 28 mai
11:20 - 11:45 Sjanne Zeijlemaker (Eindhoven University of Technology), Optimization of eigenvalue bounds for the independence and chromatic number of graph powers
11:50 - 12:15 Nathan Lindzey (University of Colorado, Boulder), Some Recent Applications of Association Schemes
12:20 - 12:45 Sidhanth Mohanty (University of California, Berkeley), On the relationship between spectra, girth and vertex expansion in regular graphs
12:50 - 13:15 Theo McKenzie (University of California, Berkeley), Support of Closed Walks and Second Eigenvalue Multiplicity of Graphs
 
The Metric Dimension of a Graph and its Variants - Part I (CM15)
Org: Shonda Dueck (University of Winnipeg)
Motivated by the problem of efficiently locating a moving point or intruder in a network, the concept of the metric dimension of a graph was first introduced by Slater, and independently by Harary and Melter, in the mid 1970's. This graph parameter has applications in network discovery and verification, combinatorial optimization, chemistry, and many other areas. The problem of determining the metric dimension of a graph is NP hard, and so researchers focus on bounding this parameter in terms of its diameter, order and size, and on determining the metric dimension of different classes of graphs. Several interesting and useful variants of the metric dimension have also been introduced over the years, such as the partition dimension, the strong dimension, the edge dimension, the threshold dimension, and the threshold strong dimension of a graph. In this minisymposium, we present several recent developments in research on the metric dimension of graphs.
 
mercredi 26 mai
11:20 - 11:45 Florent Foucaud (University Clermont Auvergne, France), Bounds on the order of a graph of given metric dimension and diameter: studies for standard graph classes
11:50 - 12:15 Ismael Gonzalez Yero (Universidad de Cadiz, Spain), Comparing the metric and edge metric dimensions of graphs
12:20 - 12:45 Tero Laihonen (Turku University, Finland), On Vertices Belonging to Every Metric Basis
12:50 - 13:15 Elizabeth Maritz (University of the Free State, South Africa), On the partition dimension of circulant graphs
13:20 - 13:45 Dorota Kuziak (Universidad de Cadiz, Spain), The strong metric dimension of a graph
 
The Metric Dimension of a Graph and its Variants - Part II (CM21)
Org: Shonda Dueck (University of Winnipeg)
Motivated by the problem of efficiently locating a moving point or intruder in a network, the concept of the metric dimension of a graph was first introduced by Slater, and independently by Harary and Melter, in the mid 1970's. This graph parameter has applications in network discovery and verification, combinatorial optimization, chemistry, and many other areas. The problem of determining the metric dimension of a graph is NP hard, and so researchers focus on bounding this parameter in terms of its diameter, order and size, and on determining the metric dimension of different classes of graphs. Several interesting and useful variants of the metric dimension have also been introduced over the years, such as the partition dimension, the strong dimension, the edge dimension, the threshold dimension, and the threshold strong dimension of a graph. In this minisymposium, we present several recent developments in research on the metric dimension of graphs.
 
jeudi 27 mai
11:20 - 11:45 Shonda Dueck (University of Winnipeg, Canada), Logarithmic bounds on the threshold strong dimension of a graph
11:50 - 12:15 Beth Novick (Clemson University, USA), A geometric characterization of the threshold strong dimension of a graph
12:20 - 12:45 Linda Eroh (University of Wisconsin, Oshkosh Campus, USA), The threshold strong dimension of trees
12:50 - 13:15 Richard Tillquist (University of Colorado, USA), A Bound on the Metric Dimension of Hamming Graphs and Applications in Machine Learning