Analytic and Probabilistic Techniques in Combinatorics - Part I (CM1) Org: Jan Volec (Emory University and Universitat Hamburg) Contemporary combinatorics is an exciting and rapidly growing discipline on the frontier of mathematics and computer science. Many new techniques in combinatorics rely on applications of tools from other mathematical areas such as algebra, analysis and probability. In the last decade, various novel methods have emerged. For example, recent works in the probabilistic method culminated with the celebrated container method which answered many long-standing open problems, new developments of algebraic techniques were crucial in settling famous conjectures in design theory or number theory, analytic approaches to Szemerédi's regularity lemma served as the corner-stone of graph limits, which then spin-off to techniques for large networks and development of flag algebras. In this mini-symposium, we aim to bring researchers in combinatorics in order to present further developments and applications of these methods, and talk about completely new approaches. We will discuss relevant open problems, exchange research ideas, and initiate new collaborations. jeudi 30 mai 10:30 - 10:50 Debsoumya Chakraborti (Carnegie Mellon University), Extremal Graphs With Local Covering Conditions, Canfor Policy Room 1600 10:55 - 11:15 Joonkyung Lee (Universitat Hamburg), On triangulated common graphs, Canfor Policy Room 1600 11:20 - 11:40 Jon Noel (University of Warwick), Cycles of length three and four in tournaments, Canfor Policy Room 1600 11:45 - 12:05 Yanitsa Pehova (University of Warwick), Decomposing graphs into edges and triangles, Canfor Policy Room 1600 12:10 - 12:30 Florian Pfender (University of Colorado Denver), 5-Cycles in Graphs, Canfor Policy Room 1600 Analytic and Probabilistic Techniques in Combinatorics - Part II (CM2) Org: Jan Volec (Emory University and Universitat Hamburg) Contemporary combinatorics is an exciting and rapidly growing discipline on the frontier of mathematics and computer science. Many new techniques in combinatorics rely on applications of tools from other mathematical areas such as algebra, analysis and probability. In the last decade, various novel methods have emerged. For example, recent works in the probabilistic method culminated with the celebrated container method which answered many long-standing open problems, new developments of algebraic techniques were crucial in settling famous conjectures in design theory or number theory, analytic approaches to Szemerédi's regularity lemma served as the corner-stone of graph limits, which then spin-off to techniques for large networks and development of flag algebras. In this mini-symposium, we aim to bring researchers in combinatorics in order to present further developments and applications of these methods, and talk about completely new approaches. We will discuss relevant open problems, exchange research ideas, and initiate new collaborations. jeudi 30 mai 15:30 - 15:50 Robert Hancock (Masaryk University), Some results in 1-independent percolation, Canfor Policy Room 1600 15:55 - 16:15 Guilherme Oliveira Mota (Universidade Federal do ABC), The multicolour size-Ramsey number of powers of paths, Canfor Policy Room 1600 16:20 - 16:40 Robert Šámal (Charles University), A rainbow version of Mantel's Theorem, Canfor Policy Room 1600 16:45 - 17:05 Maryam Sharifzadeh (University of Warwick), Graphons with minimum clique density, Canfor Policy Room 1600 Average Graph Parameters - Part I (CM3) Org: Lucas Mol et Ortrud Oellermann (University of Winnipeg) Probably the oldest and most well-known average graph parameter, the average distance of a graph - also known as the Wiener index, dates back to 1947. Of particular interest is the close correlation of the Wiener index of the molecular graph and the chemical properties of the substance such as the boiling point, viscosity and surface tension. In this minisymposium results on various average graph parameters such as the average distance in a digraph, the average order of subtrees of trees and some of its generalizations, as well as the average connectivity of graphs and digraphs are presented. jeudi 30 mai 10:30 - 10:50 Lucas Mol (University of Winnipeg), The Mean Subtree Order and the Mean Connected Induced Subgraph Order, Sauder Industries Policy Room 2270 10:55 - 11:15 Stephan Wagner (Stellenbosch University), Extremal subtree densities of trees, Sauder Industries Policy Room 2270 11:20 - 11:40 Hua Wang (Georgia Southern University), Average distance between leaves and peripheral vertices, Sauder Industries Policy Room 2270 11:45 - 12:05 Pengyu Liu (Simon Fraser University), A polynomial metric on rooted binary tree shapes, Sauder Industries Policy Room 2270 Average Graph Parameters - Part II (CM4) Org: Lucas Mol et Ortrud Oellermann (University of Winnipeg) Probably the oldest and most well-known average graph parameter, the average distance of a graph - also known as the Wiener index, dates back to 1947. Of particular interest is the close correlation of the Wiener index of the molecular graph and the chemical properties of the substance such as the boiling point, viscosity and surface tension. In this minisymposium results on various average graph parameters such as the average distance in a digraph, the average order of subtrees of trees and some of its generalizations, as well as the average connectivity of graphs and digraphs are presented. jeudi 30 mai 15:30 - 15:50 Stijn Cambie (Radboud University), Asymptotic resolution of a question of Plesník, Sauder Industries Policy Room 2270 15:55 - 16:15 Peter Dankelmann (University of Johannesburg), The average distance of maximal planar graphs, Sauder Industries Policy Room 2270 16:20 - 16:40 Suil O (State University of New York, Korea), Average connectivity and average edge-connectivity in graphs, Sauder Industries Policy Room 2270 16:45 - 17:05 Ortrud Oellermann (University of Winnipeg), The average connectivity of minimally $2$-connected graphs, Sauder Industries Policy Room 2270 Bootstrap Percolation (CM5) Org: Natasha Morrison (Instituto National de Matemática Pura e Aplicada) et Jonathan Noel (University of Warwick) Bootstrap percolation is a process on graphs which models real world phenomena including the dynamics of ferromagnetism and the spread of opinions in a social network. Topics covered in this minisymposium include recent breakthroughs on old and difficult problems alongside some of the most exciting new research directions in the area. mardi 28 mai 15:30 - 15:50 Janko Gravner (University of California, Davis), Polluted Bootstrap Percolation, McCarthy Tetrault Lecture Room 2245 15:55 - 16:15 Lianna Hambardzumyan (McGill University), Polynomial method and graph bootstrap percolation, McCarthy Tetrault Lecture Room 2245 16:20 - 16:40 David Sivakoff (The Ohio State University), Bootstrap percolation on Cartesian products of lattices with Hamming graphs, McCarthy Tetrault Lecture Room 2245 16:45 - 17:05 Ivailo Hartarsky (École normale supérieure de Lyon), The second term for two-neighbour bootstrap percolation in two dimensions, McCarthy Tetrault Lecture Room 2245 Colourings and homomorphisms (CM6) Org: Gary MacGillivray (University of Victoria) The talks focus on aspects of graph colouring and homomorphisms including fractional colourings, oriented colourings, geometric homomorphisms and reconfiguration problems. jeudi 30 mai 10:30 - 10:50 Debra Boutin (Hamilton College), Geometric Homomorphisms and the Geochromatic Number, Scotiabank Lecture Room 1315 10:55 - 11:15 Richard Brewster (Thompson Rivers University), The complexity of signed graph homomorhpisms, Scotiabank Lecture Room 1315 11:20 - 11:40 Christopher Duffy (University of Saskatchewan), Colourings, Simple Colourings, and a Connection to Bootstrap Percolation, Scotiabank Lecture Room 1315 11:45 - 12:05 John Gimbel (University of Alaska), Bounds on the fractional chromatic number of a graph., Scotiabank Lecture Room 1315 12:10 - 12:30 Jae-Baek Lee (Kyungpook National University), Reconfiguring Reflexive Digraphs, Scotiabank Lecture Room 1315 Covering Arrays - Part I (CM7) Org: Lucia Moura (University of Ottawa) et Brett Stevens (Carleton University) A covering array with $N$ rows, $k$ columns, $v$ symbols and strength $t$ is an $N \times k$ array with entries from a $v$-ary alphabet such that each of its subarrays with $t$ columns contains every $t$-tuple of the alphabet at least once as a row. Covering arrays have gained a lot of attention in the theory of combinatorial designs and in applications to software and network testing. Classical covering arrays and their many generalizations have interesting relations to areas of combinatorics such as extremal set theory, finite fields, graph homomorphisms, covering codes and combinatorial group testing. Methods for their construction range from recursive and algebraic to probabilistic and computational. In this two-part mini-symposium, we have a collection of talks highlighting current research on various aspects of covering arrays. vendredi 31 mai 10:30 - 10:50 Brett Stevens (Carleton University), Introduction to covering arrays, Canfor Policy Room 1600 10:55 - 11:15 Yasmeen Akhtar (Arizona State University, USA), Constructing High Index Covering Arrays and Their Application to Design of Experiments, Canfor Policy Room 1600 11:20 - 11:40 Kirsten Nelson (Carleton University), Constructing covering arrays from interleaved sequences, Canfor Policy Room 1600 11:45 - 12:05 Myra B. Cohen (Iowa State University), Learning to Build Covering Arrays with Hyperheuristic Search, Canfor Policy Room 1600 Covering Arrays - Part II (CM8) Org: Lucia Moura (University of Ottawa) et Brett Stevens (Carleton University) A covering array with $N$ rows, $k$ columns, $v$ symbols and strength $t$ is an $N\times k$ array with entries from a $v$-ary alphabet such that each of its subarrays with $t$ columns contains every $t$-tuple of the alphabet at least once as a row. Covering arrays have gained a lot of attention in the theory of combinatorial designs and in applications to software and network testing. Classical covering arrays and their many generalizations have interesting relations to areas of combinatorics such as extremal set theory, finite fields, graph homomorphisms, covering codes and combinatorial group testing. Methods for their construction range from recursive and algebraic to probabilistic and computational. In this two-part mini-symposium, we have a collection of talks highlighting current research on various aspects of covering arrays. vendredi 31 mai 15:30 - 15:50 Lucia Moura (University of Ottawa), Getting hyper with covering arrays, Canfor Policy Room 1600 15:55 - 16:15 Anant Godbole (East Tennessee State University, USA), Covering Arrays for Some Equivalence Classes of Words, Canfor Policy Room 1600 16:20 - 16:40 Muhammad Javed (Ryerson University), Sequence Covering Arrays, Canfor Policy Room 1600 16:45 - 17:05 André Castoldi (Universidade Tecnológica Federal do Paraná, Brazil), Bounds on Covering Codes in Rosenbloom-Tsfasman Spaces using Ordered Covering Arrays, Canfor Policy Room 1600 Design Theory - Part I (CM9) Org: Andrea Burgess (University of New Brunswick), Peter Danziger (Ryerson University) et David Pike (Memorial University of Newfoundland) 2019 marks the 175th anniversary of the birth of F\'{e}lix Walecki, who did pioneering work in design theory, particularly in factorizations and cycle decompositions of the complete graph. In addition to celebrating this event, this minisymposium brings together leading and emerging researchers in combinatorial design theory to share their results pertaining to designs and related structures, their properties and applications. mercredi 29 mai 15:30 - 15:50 Esther Lamken (California Institute of Technology), Constructions and uses of incomplete pairwise balanced designs, Canadian Pacific Lecture Room 1530 15:55 - 16:15 Peter Dukes (University of Victoria), Packings of 4-cliques in complete graphs, Canadian Pacific Lecture Room 1530 16:20 - 16:40 Flora Bowditch (University of Victoria), Localized Structure in Graph Decompositions, Canadian Pacific Lecture Room 1530 16:45 - 17:05 Iren Darijani (Memorial University of Newfoundland), k-colourings of star systems, Canadian Pacific Lecture Room 1530 Design Theory - Part II (CM10) Org: Andrea Burgess (University of New Brunswick), Peter Danziger (Ryerson University) et David Pike (Memorial University of Newfoundland) 2019 marks the 175th anniversary of the birth of F\'{e}lix Walecki, who did pioneering work in design theory, particularly in factorizations and cycle decompositions of the complete graph. In addition to celebrating this event, this minisymposium brings together leading and emerging researchers in combinatorial design theory to share their results pertaining to designs and related structures, their properties and applications. jeudi 30 mai 10:30 - 10:50 Marco Buratti (Università degli Studi di Perugia), Cyclic designs: some selected topics, McLean Management Studies Lab 2945 10:55 - 11:15 Saad El-Zanati (Illinois State University), On edge orbits and hypergraph designs, McLean Management Studies Lab 2945 11:20 - 11:40 Francesca Merola (Università Roma Tre), Cycle systems of the complete multipartite graph, McLean Management Studies Lab 2945 11:45 - 12:05 Mateja Sajna (University of Ottawa), On the Honeymoon Oberwolfach Problem, McLean Management Studies Lab 2945 12:10 - 12:30 Sibel Ozkan (Gebze Technical University), On The Hamilton-Waterloo Problem and its Generalizations, McLean Management Studies Lab 2945 Design Theory - Part III (CM11) Org: Andrea Burgess (University of New Brunswick), Peter Danziger (Ryerson University) et David Pike (Memorial University of Newfoundland) 2019 marks the 175th anniversary of the birth of F\'{e}lix Walecki, who did pioneering work in design theory, particularly in factorizations and cycle decompositions of the complete graph. In addition to celebrating this event, this minisymposium brings together leading and emerging researchers in combinatorial design theory to share their results pertaining to designs and related structures, their properties and applications. jeudi 30 mai 15:30 - 15:50 Doug Stinson (University of Waterloo), Constructions of optimal orthogonal arrays with repeated rows, McLean Management Studies Lab 2945 15:55 - 16:15 Brett Stevens (Carleton University), Affine planes with ovals for blocks, McLean Management Studies Lab 2945 16:20 - 16:40 Trent Marbach (Nankai University), Balanced Equi-n-squares, McLean Management Studies Lab 2945 16:45 - 17:05 Hadi Kharighani (University of Lethbridge), Unbiased Orthogonal Designs, McLean Management Studies Lab 2945 Elegant and Discrete Mathematics (CM12) Org: Karen Meagher (University of Regina) Discrete math is famous for being an area of mathematics where the problems are easy to state, but difficult to prove. This session will focus on results where the problems are easy to state, but the solutions are surprisingly elegant and give deeper insight into the mathematics behind the problem. The speakers will each describe an elegant new result in their field. The talks will focus on key ideas in the proofs and the intriguing aspects of their results. The goal is to offer some entry points into modern algebraic combinatorics, enumerative combinatorics, graph theory, and extremal set theory. mardi 28 mai 15:30 - 15:50 Karen Meagher (University of Regina), All 2-transitive groups have the Erdos-Ko-Rado Property, McLean Management Studies Lab 2945 15:55 - 16:15 Marni Mishna (Simon Fraser University), On the complexity of the cogrowth sequence, McLean Management Studies Lab 2945 16:20 - 16:40 Jessica Striker (North Dakota State University), Bijections - Marvelous, Mysterious, and Missing, McLean Management Studies Lab 2945 16:45 - 17:05 Steph van Willigenburg (Univeristy of British Columbia), The positivity of trees, McLean Management Studies Lab 2945 17:10 - 17:30 Hanmeng (Harmony) Zhan (Université de Montréal), Some elegant results in algebraic graph theory, McLean Management Studies Lab 2945 Finite Fields in Discrete Mathematics - Part I (CM13) Org: Petr Lisonek (Simon Fraser University) et Daniel Panario (Carleton University) In this minisymposium several topics in discrete mathematics where finite fields play an important role are presented. The talks show the use of finite fields to construct combinatorial objects and to prove interesting results in areas such as designs, graphs, Latin squares, cryptography, Boolean functions, codes and sequences, algebraic curves and finite geometries, among others. vendredi 31 mai 10:30 - 10:50 Daniel Panario (Carleton University), Finite Fields in Discrete Mathematics, Sauder Industries Policy Room 2270 10:55 - 11:15 Thais Bardini Idalino (University of Ottawa), Embedding cover-free families and cryptographical applications, Sauder Industries Policy Room 2270 11:20 - 11:40 Daniele Bartoli (University of Perugia), More on exceptional scattered polynomials, Sauder Industries Policy Room 2270 11:45 - 12:05 Claudio Qureshi (University of Campinas), Dynamics of Chebyshev polynomials over finite fields, Sauder Industries Policy Room 2270 12:10 - 12:30 Anne Canteaut (Inria Paris), Searching for APN permutations with the butterfly construction, Sauder Industries Policy Room 2270 Finite Fields in Discrete Mathematics - Part II (CM14) Org: Petr Lisonek (Simon Fraser University) et Daniel Panario (Carleton University) In this minisymposium several topics in discrete mathematics where finite fields play an important role are presented. The talks show the use of finite fields to construct combinatorial objects and to prove interesting results in areas such as designs, graphs, Latin squares, cryptography, Boolean functions, codes and sequences, algebraic curves and finite geometries, among others. vendredi 31 mai 15:30 - 15:50 Sihem Mesnager (University of Paris VIII), On good polynomials over finite fields for optimal locally recoverable codes, Sauder Industries Policy Room 2270 15:55 - 16:15 Lucas Reis (University of Sao Paulo), Permutations of finite sets from an arithmetic setting, Sauder Industries Policy Room 2270 16:20 - 16:40 Daniel Katz (California State University, Northridge), Nonvanishing minors and uncertainty principles for Fourier analysis over finite fields, Sauder Industries Policy Room 2270 16:45 - 17:05 Ariane Masuda (City University of New York), Functional Graphs of R\'edei Functions, Sauder Industries Policy Room 2270 17:10 - 17:30 Petr Lisonek (Simon Fraser University), Maximally non-associative quasigroups, Sauder Industries Policy Room 2270 Finite Geometries and Applications (CM15) Org: Sam Mattheus (Vrije Universiteit Brussel) Finite geometries is the research field in which finite incidence structures, often defined over finite fields, are investigated. Among the structures of interest are vector spaces and projective spaces, generalized polygons and others. The study of these structures and their substructures is the central topic in this area for several reasons. Plenty of these substructures are investigated for their intrinsic importance and interest, others are investigated because of their relation to other research areas such as coding theory, graph theory and even number theory. In this symposium we will have a mix of both, presenting purely geometrical problems, graph theoretical problems with geometrical roots, applications to coding theory and even an application in number theory over finite fields. mardi 28 mai 10:30 - 10:50 Sam Mattheus (Vrije Universiteit Brussel), Number theory in finite fields from a geometrical point of view, Cominco Policy Room 1415 10:55 - 11:15 Jozefien D'haeseleer (Universiteit Gent), Projective solids pairwise intersecting in at least a line, Cominco Policy Room 1415 11:20 - 11:40 Jan De Beule (Vrije Universiteit Brussel), A lower bound on the size of linear sets on a projective line of finite order, Cominco Policy Room 1415 11:45 - 12:05 Lins Denaux (Universiteit Gent), Small weight code words in the code of points and hyperplanes of PG(n,q), Cominco Policy Room 1415 12:10 - 12:30 Lisa Hernandez Lucas (Vrije Universiteit Brussel), Dominating sets in finite generalized quadrangles, Cominco Policy Room 1415 Graph Polynomials - Part I (CM16) Org: Danielle Cox (Mount Saint Vincent University) et Christopher Duffy (University of Saskatchewan) Polynomials are powerful mathematical models. Many combinatorial sequences can be investigated via their associated generating polynomial. The study of graph polynomials can be found in the literature of many combinatorial problems. For instance, one can investigate combinatorial sequences associated with graph properties, such as independence or domination by looking at the analytic properties of the associated generating polynomial. Other combinatorial problems, such as network reliability and graph colouring are modelled using polynomials. This two part mini-symposium will highlight interesting new results related to the study of graph polynomials. mardi 28 mai 10:30 - 10:50 Iain Beaton (Dalhousie University), Independence Equivalence Class of Paths and Cycles, Canfor Policy Room 1600 10:55 - 11:15 Ben Cameron (Dalhousie University), The Maximum Modulus of an Independence Root, Canfor Policy Room 1600 11:20 - 11:40 Mackenzie Wheeler (University of Victorica), Chromatic Uniqueness of Mixed Graphs, Canfor Policy Room 1600 11:45 - 12:05 Lucas Mol (University of Winnipeg), The Subtree Polynomial, Canfor Policy Room 1600 12:10 - 12:30 Lise Turner (University of Waterloo), Convergence of Coefficients of the Rank Polynomial in Benjamini-Schramm Convergent Sequences of Graphs, Canfor Policy Room 1600 Graph Polynomials - Part II (CM17) Org: Danielle Cox (Mount Saint Vincent Universityx) et Christopher Duffy (Christopher Duffy) Polynomials are powerful mathematical models. Many combinatorial sequences can be investigated via their associated generating polynomial. The study of graph polynomials can be found in the literature of many combinatorial problems. For instance, one can investigate combinatorial sequences associated with graph properties, such as independence or domination by looking at the analytic properties of the associated generating polynomial. Other combinatorial problems, such as network reliability and graph colouring are modelled using polynomials. This two part mini-symposium will highlight interesting new results related to the study of graph polynomials. mardi 28 mai 15:30 - 15:50 David Wagner (University of Waterloo), Ursell inequalities for random spanning trees, Canfor Policy Room 1600 15:55 - 16:15 Christopher Duffy (University of Saskatchewan), The Oriented Chromatic Polynomial, Canfor Policy Room 1600 16:20 - 16:40 Nicholas Harvey (University of British Columbia), Computing the Independence Polynomial in Shearer's Region for the Lovasz Local Lemma, Canfor Policy Room 1600 16:45 - 17:05 Danielle Cox (Mount Saint Vincent University), Optimal Graphs for Domination Polynomials, Canfor Policy Room 1600 Graph Searching Games - Part I (CM18) Org: Anthony Bonato (Ryerson University) et Danielle Cox (Mount Saint Vincent University) In graph searching games such as Cops and Robbers, agents must capture or slow an intruder loose on a network. The rules of the game dictate how the players move and how capture occurs. The associated optimization parameter in Cops and Robbers is the cop number, which measures how many cops are needed for a guaranteed capture. The study of the cop number has lead to a number of unsolved problems, ranging from Meyniel's conjecture to Schroeder's conjecture on graphs with bounded genus. Cops and Robbers is only one graph searching game among many others, and graph searching intersects with algorithmic, structural, and probabilistic graph theory. Other recent graph searching games and processes that have generated interest are Zombies and Survivors, localization, graph burning, and Firefighting. The proposed minisymposium brings together leading researchers in graph searching, who will present state-of-the-art research in this direction. mercredi 29 mai 10:30 - 10:50 Anthony Bonato (Ryerson University), Bounds and algorithms for graph burning, Sauder Industries Policy Room 2270 10:55 - 11:15 Nancy Clarke (Acadia University), $\ell$-Visibility Cops and Robber, Sauder Industries Policy Room 2270 11:20 - 11:40 Sean English (Ryerson University), Catching Robbers Quickly and Efficiently, Sauder Industries Policy Room 2270 11:45 - 12:05 Natasha Komarov (St. Lawrence University), Containing a robber on a graph, Sauder Industries Policy Room 2270 Graph Searching Games - Part II (CM19) Org: Anthony Bonato (Ryerson University) et Danielle Cox (Mount Saint Vincent University) In graph searching games such as Cops and Robbers, agents must capture or slow an intruder loose on a network. The rules of the game dictate how the players move and how capture occurs. The associated optimization parameter in Cops and Robbers is the cop number, which measures how many cops are needed for a guaranteed capture. The study of the cop number has lead to a number of unsolved problems, ranging from Meyniel's conjecture to Schroeder's conjecture on graphs with bounded genus. Cops and Robbers is only one graph searching game among many others, and graph searching intersects with algorithmic, structural, and probabilistic graph theory. Other recent graph searching games and processes that have generated interest are Zombies and Survivors, localization, graph burning, and Firefighting. The proposed minisymposium brings together leading researchers in graph searching, who will present state-of-the-art research in this direction. mercredi 29 mai 15:30 - 15:50 Bill Kinnersley (University of Rhode Island), Cops and Lawless Robbers, Sauder Industries Policy Room 2270 15:55 - 16:15 Kerry Ojakian (Bronx Community College (C.U.N.Y.)), Graphs that are cop-win, but not zombie-win, Sauder Industries Policy Room 2270 16:20 - 16:40 Pawel Pralat (Ryerson University), Zero Forcing Number of Random Regular Graphs, Sauder Industries Policy Room 2270 16:45 - 17:05 Ladislav Stacho (Simon Fraser University), Efficient Periodic Graph Traversal on Graphs with a Given Rotation System, Sauder Industries Policy Room 2270 Graph Structure and Algorithms (CM20) Org: Kathie Cameron (Wilfrid Laurer University) et Shenwei Huang (Nankai University) Graph algorithms are at the core of discrete mathematics and computer science. They play an increasingly critical role in fundamental research as well as real applications. In this mini-symposium, we will hear a variety of exciting developments on complexity of graph problems such as colouring, $\chi$-bounds, clique minors, and hamiltonian cycles, and on structure of important classes of graphs and digraphs. vendredi 31 mai 10:30 - 10:50 Kathie Cameron (Wilfrid Laurer University), Hadwiger's Conjecture for (Cap, Even Hole)-Free Graphs, Cominco Policy Room 1415 10:55 - 11:15 Owen Merkel (University of Waterloo), An optimal $\chi$-Bound for ($P_6$, diamond)-free graphs, Cominco Policy Room 1415 11:20 - 11:40 Juraj Stacho (Google Zurich), 3-colorable Subclasses of $P_8$-free Graphs, Cominco Policy Room 1415 11:45 - 12:05 César Hernández Cruz (CINVESTAV Mexico), On the Pancyclicity of $k$-quasi-transitive Digraphs ofLlarge Diameter, Cominco Policy Room 1415 12:10 - 12:30 Pavol Hell (Simon Fraser University), Bipartite Analogues of Comparability and Co-comparability Graphs, Cominco Policy Room 1415 Matching Theory (CM21) Org: Nishad Kothari (University of Campinas) Matching Theory pertains to the study of perfect matchings in graphs. It is one of the oldest branches of graph theory that finds many applications in combinatorial optimization, and that continues to inspire new results. For several problems in Matching Theory, such as counting the number of perfect matchings, one may restrict attention to matching covered' or 1-extendable' graphs --- connected graphs in which each edge lies in some perfect matching. Lov\'asz and Plummer (1986) provide a comprehensive treatment of the subject in their book Matching Theory''. Since then, a lot more work has been done to further our understanding of the structure of $1$-extendable graphs, as well as their generalization `$k$-extendable' graphs --- connected graphs in which every matching of size $k$ may be extended to a perfect matching. In this minisymposium, we shall cover some of the recent developments in this beautiful area that continues to blossom. mercredi 29 mai 10:30 - 10:50 Marcelo Carvalho (Federal University of Mato Grosso do Sul (UFMS)), Birkhoff--von Neumann Graphs that are PM-compact, McCarthy Tetrault Lecture Room 2245 10:55 - 11:15 Nishad Kothari (University of Campinas (UNICAMP)), Constructing $K_4$-free bricks that are Pfaffian, McCarthy Tetrault Lecture Room 2245 11:20 - 11:40 Phelipe Fabres (Federal University of Mato Grosso do Sul (UFMS)), Minimal Braces, McCarthy Tetrault Lecture Room 2245 11:45 - 12:05 Michael Plummer (Vanderbilt University), Distance Matching in Planar Triangulations: some new results, McCarthy Tetrault Lecture Room 2245 12:10 - 12:30 Robert Aldred (University of Otago), Asymmetric Distance Matching Extension, McCarthy Tetrault Lecture Room 2245 Minisymposium in honor of Frank Ruskey's 65th birthday (CM22) Org: Torsten Mütze (TU Berlin) et Joe Sawada (University of Guelph) Frank Ruskey turned 65 last year, and the goal of this minisymposium is to honor his scientific achievements in discrete mathematics and theoretical computer science, by bringing together collaborators, colleagues, academic descendants and friends on this occasion. The talks center around combinatorial algorithms, Gray codes, Venn diagrams, and other discrete topics that are close to Frank's own contributions. mardi 28 mai 10:30 - 10:50 Joe Sawada (University of Guelph), From 3/30 on Frank's midterm to a career in Academia, Sauder Industries Policy Room 2270 10:55 - 11:15 Gary MacGillivray (University of Victoria), Using combinatorial algorithms to search for golf schedules, Sauder Industries Policy Room 2270 11:20 - 11:40 Alejandro Erickson (University of Victoria), Tatami Tilings in a Template for Teaching to Teenagers, Sauder Industries Policy Room 2270 11:45 - 12:05 Gara Pruesse (Vancouver Island University), Linear Extensions of Posets -- Gray codes, fast generation algorithms, and a long-standing conjecture, Sauder Industries Policy Room 2270 12:10 - 12:30 Torsten Mütze (TU Berlin), Combinatorial generation via permutation languages, Sauder Industries Policy Room 2270 Optimization, Geometry and Graphs (CM23) Org: Bruce Shepherd (UBC) This session links topics in optimization arising in geometric and graphical settings. mardi 28 mai 10:30 - 10:50 Coulter Beeson (UBC), Revisiting the Core of Papadimitriou's Multi-Flow Game, Scotiabank Lecture Room 1315 10:55 - 11:15 Will Evans (UBC), Minimizing Interference Potential Among Moving Entities, Scotiabank Lecture Room 1315 11:20 - 11:40 David Hartvigsen (Notre Dame), Finding Triangle-free 2-factors, Revisited, Scotiabank Lecture Room 1315 11:45 - 12:05 Venkatesh Srinivasan (UBC), Scalable Misinformation Prevention in Social Networks, Scotiabank Lecture Room 1315 12:10 - 12:30 Tamon Stephen (SFU), On the Circuit Diameter Conjecture, Scotiabank Lecture Room 1315 Structured families of graphs and digraphs: characterizations, algorithms and partition problems (CM24) Org: César Hernández-Cruz (CINVESTAV, Mexico) There are many graph and digraph families that can be characterized by forbidding the existence of certain substructures, e.g., induced subgraphs or minors. Two main questions naturally arise for these families: Can they be recognized efficiently? Is the characterization useful to solve hard problems efficiently in these classes? This session is devoted to the study of such graph and digraph families, their characterization theorems, and how their structure is useful to solve, or approximate, vertex partition problems (colourings, homomorphisms, vertex arboricity) efficiently. vendredi 31 mai 15:30 - 15:50 Sebastián González Hermosillo de la Maza (Simon Fraser University), Arboricity and feedbacks sets in cographs, Fletcher Challenge Theatre 1900 15:55 - 16:15 Seyyed Aliasghar Hosseini (Simon Fraser University), The evolution of the structure of ABC-minimal trees, Fletcher Challenge Theatre 1900 16:20 - 16:40 Jing Huang (University of Victoria), Graph and digraph classes arising from list homomorphism problems, Fletcher Challenge Theatre 1900 16:45 - 17:05 Mahdieh Malekian (Simon Fraser University), The structure of graphs with no $H$-immersion, Fletcher Challenge Theatre 1900 Symmetry in Graphs - Part I (CM25) Org: Joy Morris (University of Lethbridge) Symmetry in graphs has both beauty and practical implications, and typically involves the actions of permutation groups on the vertices and/or on the edges. This minisymposium will explore recent work on symmetry in graphs. Talks will emphasise situations where symmetries are limited in some way (for example, removing symmetries by colouring vertices or edges, or studying graphs that only admit specified symmetries). This is part 1 of 2. mercredi 29 mai 10:30 - 10:50 Debra Boutin (Hamilton College), New Techniques in the Cost of 2-Distinguishing Hypercubes, Canfor Policy Room 1600 10:55 - 11:15 Karen Collins (Wesleyan University), The distinguishing number of posets and lattices, Canfor Policy Room 1600 11:20 - 11:40 Richard Hammack (Virginia Commonwealth University), Edge-transitive direct products of graphs, Canfor Policy Room 1600 11:45 - 12:05 Bohdan Kivva (University of Chicago), Minimal degree of the automorphism group of primitive coherent configurations, Canfor Policy Room 1600 12:10 - 12:30 Florian Lehner (University of Warwick), On symmetries of vertex and edge colourings of graphs, Canfor Policy Room 1600 Symmetry in Graphs - Part II (CM26) Org: Joy Morris (University of Lethbridge) Symmetry in graphs has both beauty and practical implications, and typically involves the actions of permutation groups on the vertices and/or on the edges. This minisymposium will explore recent work on symmetry in graphs. Talks will emphasise situations where symmetries are limited in some way (for example, removing symmetries by colouring vertices or edges, or studying graphs that only admit specified symmetries). This is part 2 of 2. mercredi 29 mai 15:30 - 15:50 Michael Giudici (University of Western Australia), Arc-transitive bicirculants, Canfor Policy Room 1600 15:55 - 16:15 Klavdija Kutnar (University of Primorska), Hamilton paths of cubic vertex-transitive graphs, Canfor Policy Room 1600 16:20 - 16:40 Joy Morris (University of Lethbridge), Almost all Cayley digraphs are DRRs, Canfor Policy Room 1600 16:45 - 17:05 Gabriel Verret (University of Auckland), An update on the Polycirculant Conjecture, Canfor Policy Room 1600