# Graphs at Ryerson (G & R) Seminars

## Series 2017

** Monday, May 8, 2017 at 12:00pm, Location: ENG-210**

Dejan Delic, Ryerson University

From Graph isomorphism to a New Algorithm for Maltsev

Constraint Satisfaction Problems

** Monday, May 1, 2017 at 10:00am, Location: ENG-210**

Konstantinos Georgiou, Ryerson University

Search-and-Fetch with 2 Robots on a Disk

** Tuesday, April 25, 2017 at 12:00pm, Location: ENG-210**

Dr. Maksim Mironov, Moscow Institute of Physics and Technology

On Mixing in Pairwise Markov Random Fields with Application to Social Networks

** Monday, April 10, 2017 at 10:00am, Location: ENG-210**

Dr. Ewa Infeld, Ryerson University

The Graph Theory of On-line Anonymity Systems and Browsing Privacy

** Monday, March 27, 2017 at 10:00am, Location: ENG-210**

Dejan Delic, Ryerson University

Space Dichotomy for List Homomorphism Problems

** Monday, March 20, 2017 at 10:00am, Location: ENG-210**

Dr. Anthony Bonato, Ryerson University

Overprescribed Cops and Robbers

** Monday, March 6, 2017 at 10:00am, Location: ENG-210**

Dr. Edward Lee, University of Waterloo

Circle Graph Obstructions

** Monday, February 13, 2017 at 11:00am, Location: ENG-210**

Dr. Pawel Pralat, Ryerson University

Modularity of complex networks models

** Monday, February 6, 2017 at 10:00am, Location: ENG-210**

Tommaso Traetta, Ryerson University

Title: f-Pyramidal Steiner Triple Systems

** Friday, January 27, 2017 at 11:00am, Location: ENG-210**

Dr. Andrei Raigorodskii, DIHT MIPT & Yandex

The independence numbers and the chromatic numbers of random

subgraphs of Kneser graphs and their generalizations

## Series 2016

** Thursday, December 1, 2016 at 10:00am, Location: ENG-210**

Dr. Konstantinos Georgiou, Ryerson University

Geometric and Computational Aspects for Attacking Combinatorial

Optimization Problems Using Semi-Definite Programs

** Thursday, November 17, 2016 at 10:00am, Location: ENG-210**

Dr. Gokhan Yildirim, York University

On the Longest monotone and alternating subsequences of

pattern-avoiding permutations

** Thursday, November 3, 2016 at 10:00am, Location: ENG-210**

Dr. Igor Shinkar, University of California, Berkeley

On Percolation and NP-Hardness

** Thursday, October 20, 2016 at 10:00am, Location: ENG-210**

Michael Molloy, Department of Computer Science, University of Toronto

Entropy compression and the Lovasz Local Lemma

** Thursday, October 6, 2016 at 10:00am, Location: ENG-210**

Bogumil Kaminski, Warsaw School of Economics, Poland

On the relationship between call graph topology and prices on pre-paid

telecommunication market

** Thursday, September 22, 2016 at 10:00am, Location: ENG-210**

Dr. Ewa Infeld, Ryerson University

Avoidance coupling of simple random walks.

** Thursday, September 15, 2016 at 10:00am, Location: ENG-210**

Dr. Pawel Pralat, Ryerson University

Perfect matchings and Hamiltonian cycles in the preferential attachment model

** Monday, April 25, 2016 at 11:00am, Location: ENG-210**

Dejan Delic Ryerson University

Atomization of Constraint Satisfaction Problems and Partition Pebble Games

** Monday, March 21, 2016 at 12:00pm, Location: ENG-210**

Xavier Perez-Gimenez, Ryerson University

Perfect matchings and Hamilton cycles in the preferential attachment model

** Monday, March 7, 2016 at 12:00pm, Location: ENG-210**

Speaker: Andrea Burgess, University of New Brunswick (Saint John Campus)

On the Hamilton-Waterloo problem with odd cycle lengths

**Graphs at Ryerson**

Speaker: Isaac Tamblyn, University of Ontario Institute of Technology

Mapping the equilibrium phase diagram of information flow through a complex network

** Monday,February 8 , 2016 at 12:00pm, Location: ENG-210**

Speaker: Konstantinos Georgiou, Ryerson University

Fence Patrolling with Two-Speed Robots

** Monday,February 1 , 2016 at 12:00pm, Location: VIC736**

Speaker: Anthony Bonato, Ryerson University

Conjectures on Cops and Robbers Games 2.0

** Monday, January 18, 2016 at 12:00pm, Location: ENG-210**

Speaker: Tommaso Traetta, Ryerson University

Cycle systems and parallel classes

## Series 2015

** Tuesday, December 8, 2015 at 3:00pm, Location: ENG-210 **

Speaker: Perez-Gimenez, Ryerson University

The robot crawler process

** Tuesday, November 24, at 3:00pm, Location: ENG-210 **

Speaker: Peter Horak, University of Washington Tacoma

Tiling n-space by unit cubes

** Tuesday, November 17, at 3:00pm, Location: ENG-210 **

Speaker: Pawel Pralat Ryerson University

Clique colouring of random graphs

** Thuesday, October 20, at 3:00pm, Location: ENG-210 **

Speaker: Pawel Pralat Ryerson University

To Catch a Falling Robber

**Tuesday, October 6, 2015, 3:00pm Location: ENG-210 **

Speaker: Xavier Perez-Gimenez, Ryerson University

A probabilistic version of the game of Zombies and Survivors on graphs

**Tuesday, September 29, 2015, 3:00pm Location: ENG-210 **

Speaker: Benjamin Reiniger, Ryerson University

Graph coloring, sparseness, and girth

**Tuesday, September 15, 2015, 3:00pm Location: ENG-210 **

Speaker: Konstantinos Georgiou, Ryerson University

Lift and project systems performing on
the partial-vertex-cover polytope

**Friday, August 7, 2015, 11:00am Location: ENG-210 **

Speaker: Jason Brown, Dalhousie University

Optimality and Network Reliability

**Friday, July 24, 2015, 11:00am Location: ENG-210 **

Speaker: Pawel Pralat, Ryerson University

Modelling self-organizing networks

**Wednesday, May 27, 2015, 1:00pm Location: ENG-210 **

Speaker: Barbara Maenhaut, University of Queensland

Cycle decompositions of multigraphs

**Friday, May 25, 2015, 1:00pm Location: ENG-210 **

Speaker: Jim Nastos, University of British Columbia

Using Graph Classes in Social Network Analysis

**Wednesday, May 13, 2015, 1:00pm, Location: ENG-210**

Sergey Melnik, University of Limerick

Modeling complex networks' structure and dynamics

**Monday, March 23, 2015, 1:00pm, Location: ENG-210 **

Anthony Bonato, Ryerson University

Don't be dense, try hypergraphs!

**Monday, March 9, 2015, 1:00pm, Location: ENG-210 **

Speaker: Pawel Pralat, Ryerson University

Almost all 5-regular graphs have an edge orientation in which
every out-degree is either 4 or 1.

**Monday, February 23, 2015, 1:00pm, Location: ENG-210 **

Speaker: Tobias Muller, Utrecht University

A hyperbolic model for complex networks

**Monday, January 26, 2015, 1:00pm, ENG-210 **

Speaker: Jason Brown, Dalhousie University

Convexity on Graphs

**Monday, January 19, 2015, 1:00pm,1:00pm, ENG-210 **

Speaker: Xavier Perez-Gimenez, Ryerson University

Majority bootstrap percolation on regular graphs

**Monday, January 12, 2015, 1:00pm,1:00pm, ENG-210 **

Speaker: Dieter Mitsche, Universite de Nice Sophia-Antipolis

On rigidity, orientability and cores of random graphs with sliders

## Series 2014

**Monday, December 8, 2014, 1:00pm, ENG-210 **

Speaker: Jane (Pu) Gao, University of Waterloo

Clustering in random CSPs

**Monday, November 24, 2014, 1:00pm, ENG-210 **

Speaker: Jerzy Wojciechowski, West Virginia University

Algebraic Cycle Matroids

**Monday, November 17, 2014, 1:00pm, ENG-210 **

Speaker: Patrick Bennett, University of Toronto

Resolution Space in Random 3-SAT

**Monday, November 10, 2014, 1:00 pm, ENG 21**

Dennis D.A. Epple, University of Victoria

Collapse and Fibonacci words

**Monday, October 27, 2014, 1:00 pm, ENG 21**

Tommaso Traetta, Ryerson University

Factorizations, graph labelings and symmetries

**Monday, October 27, 2014, 1:00 pm, ENG 21**

Ada Chan, York University

Type II matrices, association schemes and hypercubes

**Monday, September 29, 2014, 1:00 pm, ENG 210**

Nathan Lapierre, Dalhousie University

Visualizing massive social network graphs

**Wednesday, April 23, 2014, 1:30 pm, ENG 210**

Pawel Pralat, Ryerson University

Power of k choices and rainbow spanning trees in random graphs

**Monday, September 15, 2014, 1:00 pm, ENG 210**

Elham Roshanbin, Dalhousie University

Graph burning

**Wednesday, April 23, 2014, 1:30 pm, ENG 210**

Pawel Pralat, Ryerson University

Encoding arguments instead of probability theory?

**Wednesday, April 2, 2014, 1:30 pm, ENG 210**

Saieed Akbari, Sharif University of Technology

c-Sum Flows in Graphs and 2-Designs

**Friday, March 21, 2014, 11:00 am, ENG 210**

Ben Seamone, Universite de Montreal

Cycle extendibility in Hamiltonian chordal graphs

**Wednesday, February 5, 2014 1:30 pm, ENG 210**

Patrick Bennett, University of Toronto

The t-tone chromatic number of random graphs

**Wednesday, January 22, 2014 1:30 pm, ENG 210**

Pawel Pralat, Ryerson University

Total acquisition in random graphs

## Series 2013

**Monday, December 9, 2013, 10:00 am, ENG 210**

Deepak Bal, Ryerson University

Rainbow Matchings and Hamilton Cycles in Random Graphs

**Thursday, November 28, 2013, 11:00 am, ENG 210**

Andrzej Dudek, Western Michigan University

On generalized Ramsey numbers of Erdos and Rogers

**Monday, November 11, 2013, 10:00 am, ENG 210**

Dejan Delic, Ryerson University

Homomorphism Dichotomy for Oriented Trees and Treelike

Structures Via Absorption

**Monday, November 4, 2013, 10:00 am, ENG 210**

Serge Gaspers,University of New South Wales and NICTA

Backdoors to Satisfaction

**Monday, October 28, 2013, 10:00am, ENG 210**

Bill Kinnersley, Ryerson University

The computational complexity of Cops and Robbers

**Wednesday, October 21, 2013, 10:00am, ENG 210**

Patrick Bennett, University of Toronto

The random greedy algorithm for independent sets in hypergraphs

**Wednesday, October 2, 2013, 1:00pm, ENG 210**

Jason Brown, Dalhousie University

Roots of Combinatorial Polynomials

**Monday, September 23, 2013, 10:00am, ENG 210**

Xavier Perez Gimenez, University of Waterloo

Arboricity and spanning-tree packing in random graphs with

an application to load balancing

**Monday, September 16, 2013, 10:00am, ENG 210**

Anthony Bonato,
Ryerson University

Dimension matching in Facebook and LinkedIn networks

**Tuesday, June 4, 2013, 1:15pm, ENG 210**

Robert Bailey, Ryerson University

Metric dimension of imprimitive distance-regular graphs

**Monday, June 3, 2013, 12:15pm, ENG 210**

Steve Chaplick, Charles University

Equilateral L-Contact Graphs

**Tuesday, May 14, 2013, 1:115pm, ENG 210**

Muhammad Javed, Ryerson University

Cycle decomposition of complete graphs of small orders

**Tuesday, May 7, 2013, 11:00am (note different time), ENG 210**

Dr. Rasha Kashef, University of Waterloo

Combining Multiple Partitioning Using Cooperative-based
Consensus Clustering (Model and Applications)

**Tuesday, April 23, 2013, 1:15pm, ENG 210**

Dr. Przemyslaw Gordinowicz, Technical University of Lodz, Poland

Brushing is easier when brushes can travel together

**Tuesday, April 16, 2013, 1:15pm, ENG 210**

Vivija Ping You

Department of Mathematics, Ryerson University

Distance k Cops and Robbers and Brush Cleaning on Graphs

**Tuesday, April 2, 2013, 1:15pm, ENG 210**

Pawel Pralat

Department of Mathematics, Ryerson University

Cops and Robbers playing on edges

**Tuesday, February 26, 2013, 1:15 pm, ENG 210**

Dr. Dejan Delic

Ryerson University

Expressibility of digraph homomorphisms in logic LFP+Rank

**Tuesday, February 5, 2013, 1:15 pm, ENG 210**

Dr. Peter Danziger

Ryerson University

The Generalised Oberwolfach Problem: The Bipartite Case

**Tuesday, January 22, 2013, 1:15 pm, ENG 210**

Dr. Andrea Burgess

Ryerson University

Asymptotic enumeration of sparse
strongly connected digraphs by vertices and edges.

## Series 2012

**Wednesday, November 21, 2012, 1:15 pm, ENG 210**

Dr. Xavier Perez Gimenez

University of Waterloo

Asymptotic enumeration of sparse
strongly connected digraphs by vertices and edges.

** Wednesday, November 7, 2012, 1:15pm, ENG 210**

Dr. Robert Bailey

Ryerson University

Orthogonal matrices with zero diagonal,
and eigenvalues of graphs

** Wednesday, October 17, 2012, 1:15pm, ENG 210**

Dr. Bill Kinnersley

Ryerson University

Degree Ramsey and on-line degree Ramsey numbers

**Thursday, October 3, 2012, 1:15pm, ENG 210 **

Przemyslaw Gordinowicz

Technical University of Lodz

The countable p.e.c. graph and its automorphisms

**Wednesday, September 26, 2012, 1:15pm, ENG 210 **

Pawel Pralat

Department of Mathematics, Ryerson University

Metric dimension for random graphs

**Wednesday, September 12, 2012, 1:15pm, ENG 210 **

Anthony Bonato

Department of Mathematics, Ryerson University

Generalized vertex-pursuit games

**Thursday, June 7, 2012, 10:30am, ENG 210**

Eric Moorhouse

Department of Mathematics, University of Wyoming

Colouring the Plane

**Thursday, May 31, 2012, 10:30am, ENG 210**

Dr.Stephen Finbow

Department of Mathematics St. Francis Xavier University

Discharging from the point of view of a fire extinguisher

**Thursday, May 24, 2012, 10:30 am, ENG 210**

Dr. Jason I. Brown

Department of Mathematics, Dalhousie University

Network Reliability

**Thursday, May 3, 2012, 10:30 am, ENG 210**

Pawel Pralat

Department of Mathematics, Ryerson University

Solutions to this year puzzles

**Thursday, April 05, 2012, 10:30 am, ENG 210**

Abbas Mehrabian

Department of Mathematics, University of Waterloo

On the density of nearly regular graphs with a good edge-labelling

**Thursday, April 19, 2012, 10:30 am, ENG 210**

Andrea Burgess

Department of Mathematics, Ryerson University

Cops and robbers on graphs based on designs

**Thursday, March 22, 2012, 10:30 am, ENG 210**

Peter Danziger

Department of Mathematics, Ryerson University

Infinitely Resolvable Designs

**Thursday, March 8, 2012, 9:45 am, ENG 210**

Dieter Mitsche

Department of Mathematics, Ryerson University

Cops and invisible robbers: the cost of drunkenness

**Thursday, February 16, 2012, 10:30 am, ENG 210**

Robert Bailey

Department of Mathematics, University of Regina

The metric dimension problem

**Thursday, February 9, 2012, 10:30 am, ENG 210**

Steven Chaplick

Department of Computer Science, University of Toronto

Path Graphs and PR-trees

## Series 2011

**Thursday, November 24, 2011, 1:00 pm, ENG 210**

Dr. Mike Molloy

Department of Computer Science, University of Toronto

Frozen vertices in colourings
of a random graph

**Thursday, November 3, 2011, 1:00 pm, ENG 210**

Andrea
Burgess

Department of Mathematics, Ryerson
University

Near factorizations of complete graphs

**Thursday, November 3, 2011, 12:40 pm, ENG
210**

Dejan
Delic

Department of Mathematics, Ryerson University

Hard vs easy algorithms:
how doesgraph theory help us?

**Thursday, October 20, 2011, 1:00 pm, ENG
210**

Steve
Chaplick

Department of Computer Science, University
of Toronto

Path
Graphs and PR-trees

**Thursday,October 13 , 2011, 1:00 pm, ENG 210**

Dr. Dejan Delic

Department of Mathematics, Ryerson University

Reduction of CSP Dichotomy to
Digraphs - Part II

**Thursday, Sept 29, 2011, 1:00 pm, ENG 210**

Dr. Dejan Delic

Department of Mathematics, Ryerson University

Reduction of CSP Dichotomy to Digraphs - Part I

**Thursday, Sept 15, 2011, 1:30 pm, ENG 210**

Dr. Anthony Bonato

Department of Mathematics, Ryerson University

Problems and conjectures on Cops and Robbers

**Thursday, May 12, 2011, 10:30 am, ENG 210**

Tamar Krikorian

Department of Mathematics, Ryerson University

OA's, OOA's, OCA's and MOCA's

**Thursday, April 14, 2011, 10:30 am, ENG 210**

Liam Baird

Department of Mathematics, Ryerson University

Meyniel extremal families of graphs

**Friday, March 25, 2011, 10:00 am, ENG 210**

Richard Nowakowski

Department of Mathematics & Statistics, Dalhousie University

A survey on the search for well-covered atoms

**Thursday, March 10, 2011, 10:00 am, ENG 210**

Andrea Burgess

Department of Mathematics, Ryerson University

Generalized packing designs

**Thursday, January 27, 2011, 10:30 am, ENG 210**

Nevena Francetic, University of Toronto

Department of Mathematics, University of Toronto

Covering arrays with row limit

**Thursday, January 13, 2011, 10:30 am, ENG 210**

Dr. Dejan Delic

Department of Mathematics, Ryerson University

Tree Dualities and Orderings on Oriented Trees

## Series 2010

**Friday, November 26, 2010, 2:00 pm, ENG 210**

Pawel Pralat

Department of Mathematics, West Virginia University

Meyniel's conjecture holds for random graphs

**Tuesday, November 2, 2010, 2:00 pm, ENG 210**

Changping Wang

Department of Mathematics, Ryerson University

Orthogonal (g,f)-factorizations in graphs

**Tuesday, October 19, 2010, 2:00 pm, ENG 210**

Peter Danziger

Department of Mathematics, Ryerson University

The Oberwolfach and related problems

**Tuesday, October 5, 2010, 2:00 pm, ENG 210**

Graeme Kemkes

Department of Mathematics, Ryerson University

Random regular graphs

**Tuesday, September 21, 2010, 2:00 pm, ENG 210**

Anthony Bonato

Department of Mathematics, Ryerson University

Graph densities

**Tuesday, March 30, 2010, 2:00 pm, ENG 210**

Pawel Pralat

Department of Mathematics, Ryerson University

Graphs with average degree smaller than 30/11 are burning slowly

**Tuesday, March 16, 2010, 2:00 pm, ENG 210**

Dejan Delic

Department of Mathematics, Ryerson University

Homomorphism Testing Strategies For Finite Digraphs

**Tuesday, March 12, 2010, 2:00 pm, ENG 210**

Changping Wang

Department of Mathematics, Ryerson University

Some Problems on Domination

**Tuesday, February 9, 2010, 2:00 pm, ENG 210**

Peter Danziger

Department of Mathematics, Ryerson University

MOLS: Bachelors and Monogamous Mates

**Tuesday, January 26, 2010, 2:00 pm, ENG 210**

Margaret-Ellen Messinger

Department of Mathematics, Mount Allison University

Cleaning A Network with Mechanized Brushes

**Tuesday, January 12, 2010, 2:00 pm, ENG 210**

Anthony Bonato

Department of Mathematics, Ryerson University

Meyniels Conjecture