# Contributed Minisymposia

There will be contributed minisymposia in the following areas.

Algebraic graph theory in quantum computing

Quantum walks are an important concept in the study of quantum algorithms. Quantum walk algorithms have been studied and shown to perform exponentially or polynomially better for various black box problems. Problems about quantum walks on graphs have also produced numerous interesting mathematical problems, where techniques in algebraic graph theory have yielded new advances. This minisymposium will give an overview of recent work along this vein, as well as encourage further collaboration. Other organizers: Chris Godsil (University of Waterloo), Krystal Guo (University of Waterloo), and Christino Tamon (Clarkson University)

Mark Kempton (Harvard University), Christopher van Bommel (University of Waterloo), Luc Vinet (University of Montreal), Thomas Wong (University of Texas at Austin), Harmony Zhan (University of Waterloo).

Average Graph Parameters I
Org: Ortrud Oellermann and Lucas Mol (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 reliability of a graph and their relationships with the structural properties of the (di)graph are presented.

Danielle Cox (Mount Saint Vincent University), Peter Dankelmann (University of Johannesburg), Lucas Mol (University of Winnipeg), Ortrud Oellermann (University of Winnipeg), Hua Wang (Georgia Southern University).

Combinatorial Gray codes
Org: Jan Goedgebeur (Ghent University) and Torsten MÃ¼tze (TU Berlin)

Generating all the objects in a particular class (e.g. permutations, subsets, strings, trees, graphs etc.) such that each object is generated exactly once is one of the oldest and most basic combinatorial problems, with a large number of practical applications. In fact, more than half of Donald Knuth's most recent book in the seminal series 'The Art of Computer Programming' is entirely devoted to this fundamental subject. This minisymposium aims at presenting some of the exciting recent developments in the area of combinatorial Gray codes, and to circulate challenging open problems among researchers in the field. This minisymposium has a companion entitled Computational combinatorics' in which such generation algorithms have been applied successfully to solve various combinatorial problems.

Torsten MÃ¼tze (TU Berlin), Joe Sawada (University of Guelph), Aaron Williams (Bard College at Simon's Rock), Dennis Wong (Northwest Missouri State University).

Combinatorial Optimization
Org: Guyslain Naves (Aix-Marseille University) and Bruce Shepherd (McGill)

Min-max results (exact and approximate) and new models in combinatorial optimization arising from flows, cuts, and matroids.

Ahmad Abdi (Waterloo), Andras Frank (Eotvos Lorand University), Vivek Madan (Uuniversity Illininois Urbana-Champaign), Richard Santiago (McGill University), Bruce Shepherd (McGill University).

Computational combinatorics
Org: Jan Goedgebeur (Ghent University) and Torsten MÃ¼tze (TU Berlin)

Computers are often used in combinatorics to determine if combinatorial objects with given structural or extremal properties exist as these existence problems are often too complex to solve by hand. This is done by designing and implementing generation algorithms which construct combinatorial objects from a given class (typically avoiding the generation of isomorphic copies). This minisymposium presents some recent examples where computers have been successfully used to solve problems in graph colouring, Hamiltonicity and Ramsey theory. This minisymposium has a companion entitled Combinatorial Gray codes', covering algorithms for generating various families of combinatorial objects, which are an essential tool for such exhaustive enumeration approaches.

Richard Brewster (Thompson Rivers University), Jan Goedgebeur (Ghent University), Gary MacGillivray (University of Victoria), Stanislaw Radziszowski (Rochester Institute of Technology).

Discrete Mathematical Biology, Part I
Org: Torin Greenwood and Christine Heitsch (Georgia Institute of Technology)

This pair of minisymposia will examine discrete models and combinatorial methods across a spectrum of mathematical biology. Problems in biology motivate new combinatorial methods, which have intrinsic mathematical appeal. Complementing this, new mathematical techniques bring advancements to biology. These talks exhibit the fruitful interplay between the fields.

Sharlee Climer (University of Missouri - St. Louis), Joanna Ellis-Monaghan (Saint Michael's College), Torin Greenwood (Georgia Institute of Technology), Ezra Miller (Duke University), Sonja Petrovic (Illinois Institute of Technology).

Discrete Mathematical Biology, Part II
Org: Torin Greenwood and Christine Heitsch (Georgia Institute of Technology)

This pair of minisymposia will examine discrete models and combinatorial methods across a spectrum of mathematical biology. Problems in biology motivate new combinatorial methods, which have intrinsic mathematical appeal. Complementing this, new mathematical techniques bring advancements to biology. These talks exhibit the fruitful interplay between the fields.

Peter Clote (Boston College), Elena Dimitrova (Clemson University), Tara Petrie (Simon Fraser University), Christian Reidys (Virginia Institute of Technology), David Sivakoff (Ohio State University).

Entropy compression and the Lovasz Local Lemma
Org: Michael Molloy (University of Toronto)

The Lovasz Local Lemma is a powerful proof technique which proves the existence of an object, by showing that a random procedure attempting to produce it will succeed with positive probability. For example, every graph with certain properties has a colouring of a certain type. $\\$ In 2008, Moser introduced entropy compression, a technique to provide efficient algorithms which construct objects that the Local Lemma guarantees to exist. His technique has since been used to obtain new existence proofs using procedures where it is hard to apply traditional versions of the Local Lemma. For example, one can try to colour a graph by colouring vertices one-at-a-time, each time choosing a random colour that does not appear on the neighbourhood of the vertex. The spread of dependencies in such a procedure is usually too much for the Local Lemma. But procedures of this type can fit quite well into Moser's framework.

Fotis Iliopoulos (UC Berkeley), Gwenael Joret (UniversitÃ© Libre de Bruxelles), Piotr Micek (Jagiellonian University), Michael Molloy (University of Toronto).

Geometry and Combinatorial Optimization
Org: Guyslain Naves (Aix-Marseille University)

This session's focus is on geometric aspects of combinatorial optimization.

Marcel Celaya (Georgia Tech), Robert Davis (Michigan State University), Guyslain Naves (Marseille University), Andras Sebo (Grenoble).

Graph Colouring, Part I
Org: Luke Postle (University of Waterloo)

Graph coloring is one the oldest and most storied areas of graph theory. Despite dating back to the days of the Four Color Conjecture, there has been much recent interest and active progress in this area, especially in the last few decades. Many generalizations of graph coloring, developed to tackle practical problems, can be extended beyond their original applications in order to attack new areas. This two-part minisymposium seeks to highlight a number of these interesting new developments by bringing together researchers in this classical field.

Michelle Delcourt (University of Illinois at Urbana-Champaign), Thomas Kelly (University of Waterloo), Sophie Spirkl (Princeton University), David Wood (Monash University), Yelena Yuditsky (McGill University).

Graph Colouring, Part II
Org: Michelle Delcourt (University of Illinois at Urbana-Champaign)

Graph coloring is one the oldest and most storied areas of graph theory. Despite dating back to the days of the Four Color Conjecture, there has been much recent interest and active progress in this area, especially in the last few decades. Many generalizations of graph coloring, developed to tackle practical problems, can be extended beyond their original applications in order to attack new areas. This two-part minisymposium seeks to highlight a number of these interesting new developments by bringing together researchers in this classical field.

Anton Bernshteyn (University of Illinois at Urbana-Champaign), Vida Dujmovic (University of Ottawa), Ararat Harutyunyan (University of Toulouse), Luke Postle (University of Waterloo), Hehui Wu (Shanghai Center for Mathematical Sciences).

Graph Polynomials
Org: Jason Brown (Dalhousie University)

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 (such as independence and domination) leads one to explore the associated combinatorial sequences by formulating generating polynomials. In all cases, polynomials carry useful or even essential information about the underlying combinatorics, and the connections allow one to draw on classical areas of mathematics, such as analysis and algebra, in the investigations.

Jason Brown (Dalhousie University), Ben Cameron (Dalhousie University), Danielle Cox (Mount Saint Vincent University), Lucas Mol (University of Winnipeg), David Wagner (University of Waterloo).

Graph Structure and Algorithms I
Org: Kathie Cameron and Shenwei Huang (Wilfrid Laurier University / University of New South Wales)

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 classical and parameterized complexity of graph problems such as coloring, homomorphisms and graph search, and on structure of important classes of graphs and digraphs.

CÃ©sar HernÃ¡ndez Cruz (Universidad Nacional AutÃ³noma de MÃ©xico), Jing Huang (University of Victoria), Shenwei Huang (University of New South Wales), Edward Lee (University of New South Wales), Arash Rafiey (Indiana State University).

Graph Structure and Algorithms II
Org: Kathie Cameron and Shenwei Huang (Wilfrid Laurier University / University of New South Wales)

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 classical and parameterized complexity of graph problems such as coloring, homomorphisms and graph search, and on structure of important classes of graphs and digraphs.

Kathie Cameron (Wilfrid Laurier University), Elaine Eschen (West Virginia University), Pavol Hell (Simon Fraser University), Chinh Hoang (Wilfrid Laurier University), R. Sritharan (University of Dayton).

Graphs and Games: the Mathematics of Richard Nowakowski (Part I)
Org: Shannon Fitzpatrick (University of Prince Edward Island)

This minisymposium is in honour of Richard Nowakowski, on the occasion of his 65th birthday. Throughout his career, Richard has worked on a variety of problems, but his influence has been most keenly felt in the fields of Graph Searching and Combinatorial Game Theory. This is an opportunity for Richard's former students, collaborators, and colleagues to present research in areas of particular interest to Richard, and celebrate his contribution to mathematics in Canada.

Nancy Clarke (Acadia University), Stephen Finbow (Saint Francis Xavier University), Shannon Fitzpatrick (University of Prince Edward Island), Neil McKay (University of New Brunswick, Saint John), Margaret-Ellen Messinger (Mount Allison University).

Graphs and Games: the Mathematics of Richard Nowakowski (Part II)
Org: Margaret-Ellen Messinger (Mount Allison University)

This minisymposium is in honour of Richard Nowakowski, on the occasion of his 65th birthday. Throughout his career, Richard has worked on a variety of problems, but his influence has been most keenly felt in the fields of Graph Searching and Combinatorial Game Theory. This is an opportunity for Richard's former students, collaborators, and colleagues to present research in areas of particular interest to Richard, and celebrate his contribution to mathematics in Canada.

Anthony Bonato (Ryerson University), Jason Brown (Dalhousie University), Chris Duffy (Dalhousie University), Gena Hahn (UniversitÃ© de MontrÃ©al), Pawel Pralat (Ryerson University).

Graphs and Games: the Mathematics of Richard Nowakowski (Part III)

This minisymposium is in honour of Richard Nowakowski, on the occasion of his 65th birthday. Throughout his career, Richard has worked on a variety of problems, but his influence has been most keenly felt in the fields of Graph Searching and Combinatorial Game Theory. This is an opportunity for Richard's former students, collaborators, and colleagues to present research in areas of particular interest to Richard, and celebrate his contribution to mathematics in Canada.

Art Finbow (Saint Mary's University), Bert Hartnell (Saint Mary's University), Jeannette Janssen (Dalhousie University).

In honour of the work of Alex Rosa (Part I)
Org: Peter Danziger, Tommaso Traetta (Ryerson University)

On the occasion of Alex Rosa's 80th birthday we offer these two sessions in honour of his work. Particularly known for his work on Triple Sytems, Dr. Rosa has published in many areas of Combinatorics including Graph Labellings, Steiner Triple systems and Graph Decompositions. He has over 200 refereed journal publications, many books, and was a founding editor of the Journal of Combinatorial Designs. He has been awarded the prestigous Euler medal by the Institute of Combinatorics and its Applications. He is universally recognised as one of the leading lights of modern Combinatorics, his activities and influence in Discrete Mathematics continue to this day. These sessions will highlight recent progress in areas of interest in Design Theory and beyond to which Alex has blazed the trail.

Peter Dukes (University of Victoria), FranÄ›k FrantiÅ¡ek (McMaster University), Esther Lamken (University of Caltech), Nabil Shalaby (Memorial University), Doug Stinson (University of Waterloo).

In honour of the work of Alex Rosa (Part II)
Org: Peter Danziger, Tommaso Traetta (Ryerson University)

On the occasion of Alex Rosa's 80th birthday we offer these two sessions in honour of his work. Particularly known for his work on Triple Systems, Dr. Rosa has published in many areas of Combinatorics including Graph Labellings, Steiner Triple systems and Graph Decompositions. He has over 200 refereed journal publications, many books, and was a founding editor of the Journal of Combinatorial Designs. He has been awarded the prestigious Euler medal by the Institute of Combinatorics and its Applications. He is universally recognised as one of the leading lights of modern Combinatorics, his activities and influence in Discrete Mathematics continue to this day. These sessions will highlight recent progress in areas of interest in Design Theory and beyond to which Alex has blazed the trail.

Andrea Burgess (University of New Brunswick), Barbara Maenhaut (University of Queensland), David Pike (Memorial University), Brett Stevens (Carleton University), Tommaso Traetta (Ryerson University).

Pursuit-Evasion Games on Graphs
Org: Bill Kinnersley (University of Rhode Island)

Pursuit-evasion games are a type of combinatorial game in which one or more pursuers'' attempts to capture a mobile evader'' within some environment (often represented by a graph). In addition to being of theoretical interest, pursuit-evasion games have applications in a variety of areas, from mobile computing to military operations. This minisymposium will focus on recent developments in the field, with a particular emphasis on the classic game of Cops and Robbers.

Danny Dyer (Memorial University), Saeed Aliasghar Hosseini (Simon Fraser University), Bill Kinnersley (University of Rhode Island), Natasha Komarov (St. Lawrence University), Kerry Ojakian (Bronx Community College (C.U.N.Y.)).

Reconfiguration
Org: Ruth Haas (U. Hawaii, Manoa)

The reconfiguration version of a problem concerns when one feasible solution to a problem can be reconfigured to another via an allowable set of operations. There has recently been a lot of interest in this topic including reconfiguration of graph coloring and domination among other problems These talks give an overview of the area as well as current work and open problems.

Benjamin Moore (Simon Fraser University), Moritz MÃ¼hlenthaler (Erlangen-Nurnberg), Naomi Nishimura (Waterloo), Beth Novick (Clemson University), Karen Seyffarth (U Calgary).

Topological and Geometric Algorithms, Part I
Org: Mark Ellingham and Joanna Ellis-Monaghan (Vanderbilt University and Saint Michael's College)

One of the strengths of discrete mathematics is its broad applicability in a wide range of other fields. For example, many problems in discrete mathematics have a topological or geometric component or setting. Moreover, particularly for questions driven by applications, many such problems include algorithmic approaches. This minisymposium brings together researchers whose work in discrete mathematics involves both spatial and computational considerations, many with a sub-theme of structural questions arising from biological and other applications. Examples include: graph drawing in various settings; determining folding configurations for paper, DNA, or protein structures; and generating graph embeddings with certain symmetries.

Joanna Ellis-Monaghan (Saint Michael's College), Christine Heitsch (Georgia Institute of Technology), NataÅ¡a Jonoska (University of South Florida), Ada Morse (University of Vermont).

Topological and Geometric Algorithms, Part II
Org: Mark Ellingham and Joanna Ellis-Monaghan (Vanderbilt University and Saint Michael's College)

One of the strengths of discrete mathematics is its broad applicability in a wide range of other fields. For example, many problems in discrete mathematics have a topological or geometric component or setting. Moreover, particularly for questions driven by applications, many such problems include algorithmic approaches. This minisymposium brings together researchers whose work in discrete mathematics involves both spatial and computational considerations, many with a sub-theme of structural questions arising from biological and other applications. Examples include: graph drawing in various settings; determining folding configurations for paper, DNA, or protein structures; and generating graph embeddings with certain symmetries.

Therese Biedl (University of Waterloo), Mark Ellingham (Vanderbilt University), Ellen Gethner (University of Colorado Denver), Anna Lubiw (University of Waterloo), Sue Whitesides (University of Victoria).

Handling of online submissions has been provided by the CMS.