April 14, 2024

June 20-21,2014
Conference on Graph Theory, Matrix Theory and Interactions

A Conference to celebrate the scholarship of David Gregory
Queen's University
Talks to be held at:
Department of Mathematics,
Jeffrey Hall, Queen's University, Kingston, ON

Organizing Committee
Sebastian Cioaba, Bryan Shader, Ram Murty,
Claude Tardif, Kevin Vander Meulen, David Wehlau

Conference Summary

This conference is meant to be a celebration of the scholarship of the late David A. Gregory, a long-serving Professor in the Department of Mathematics at Queen's University. David Gregory explored mathematical problems that bridged two areas of mathematics: linear algebra and discrete mathematics, especially graph theory. His insights, careful approach and writing influenced many mathematicians, especially in combinatorial matrix theory.

David's research was initially focused upon vector sequence spaces but moved into topics related to ranks, exploring Boolean rank, nonnegative rank, and even introducing a new concept, Hermitian rank. He explored algebraic connections with some graph theoretic counting problems, like finding bounds on clique cover numbers, biclique partitions, and multiclique decompositions of graphs. He was fond of exploring variations on the Graham-Pollak theorem, a result which solves a purely combinatorial problem via clever algebraic means. Following along these lines, David has been keenly interested in eigenvalues of graphs and tournaments, exploring connections to inertia of graphs, spread of the eigenvalues of a graph, and most recently, relationships between eigenvalues and the size of matchings of a graph, or the independence number.

David Gregory made many contributions to these topics. The goal of the conference is to spend some time reflecting on David's contributions, to gather researchers who have collaborated with David (of which there are many), as well as other researchers who have been influenced by his work, to explore recent developments, and to make new or stronger connections in the research community. The conference will be of interest to the linear algebra community, especially those in combinatorial matrix theory, but researchers representing any aspect of David Gregory's mathematical scholarship are invited to attend and propose a presentation.

Further, some colleagues who have worked closely with David are preparing a manuscript which surveys the scholarship of David Gregory and presents open problems that he has proposed. David left some very interesting open problems that are of interest to the wider linear algebra and discrete mathematics communities.

Publications of David Gregory

Please contact any committee member if you wish to attend and/or present, or to receive further information.

Invited Speakers:
Richard A Brualdi, University of Wisconsin
Sebastian Cioaba, University of Delaware
Edwin van Dam, Tilburg University
Randall J Elzinga, The Royal Military College of Canada
Robert Erdahl, Queen's University
Shaun Fallat, University of Regina
Chris Godsil, University of Waterloo
Willem Haemers, Tilburg University
Steve Kirkland, University of Manitoba
Kevin N. Vander Meulen, Redeemer University College
Eric Moorhouse, University of Wyoming
Ram Murty, Queen's University
Naomi Shaked-Monderer, The Max Stern Yezreel Valley College
Claude Tardif, The Royal Military College of Canada
David Wehlau, The Royal Military College of Canada

Contributing Speakers:
Aida Abiad, Tilburg University
Marina Arav, Georgia State University
Louis Deaett, Quinnipiac University
Dr. Alpesh M. Dhorajia, BITS Pilani
A. Farrag, Dalhousie University
Jan Foniok, University of Warwick
Hein van der Holst, Georgia State University
Oksana Pichugina, Brock University
Mozhgan Pourmoradnasseri, Arvutiteaduse instituut Tartu
Steven Rayan, University of Toronto
David Roberson, Nanyang Technological University
Michael Tait, University of California, San Diego
Ludmila Tsiovkina, Krasovsky Institute of Mathematics and Mechanics
Hein van der Holst, Queen's University

Dedicated Journal Issue

A special issue of the Electronic Journal of Linear Algebra will be dedicated to David Gregory.

The proceedings of this conference will appear as a volume of the Electronic Journal of Linear Algebra (ELA). Papers fitting the scope of the conference but not presented at the conference are welcome.
Editors for the volume are Sebastian Cioaba (cioaba(at), Ram P Murty (murty(at), Claude Tardif (Claude.Tardif(at), Kevin N. Vander Meulen (kvanderm(at), and David Wehlau (wehlau-d(at) The Editor-in-Chief is Bryan Shader (elamath(at)

All papers will be subject to the usual refereeing procedure for ELA. The deadline for submissions is September 22, 2014. Authors should submit a paper directly to ELA (elamath(at), and clearly indicate that the paper is to be considered for this special volume, or to one of the special editors. Submission guidelines are available at

Local Accommodation

A block of rooms has been set aside on a first-come first-serve basis at the Donald Gordon Centre.

Rooms at the Donald Gordon Centre are reserved for Friday June 20 and Saturday June 21 (there is awaiting list for Thursday June 19).

Online Reservation:
Group Code: 134830 PIN 200614
or call 1-866-455-2655
Rate: $130 Cdn plus taxes/night – including on-site parking
Location: 20 minute walk to lecture room.
Cut-off-date: June 1st, 2014.
Name of booking: David Gregory Conference

A block of suites has been set aside on a first-come first-serve basis at Leggett/Watts Hall. The suites include two rooms with a bathroom in between. Participants may make there own arrangement to share a suite to save costs, otherwise they have the whole suite to themselves. These suites are reserved for Thursday June 19 and Friday June 20. If an additional night is desired, e.g. staying a third night June 21, then please indicate so in the notes section of
the online booking.

Online Reservation:
 Group Code:    25751
  or call   613-533-2223
 Rate: $99 Cdn plus taxes/night – parking extra
Location: 5 minute walk to lecture room.
Cut-off-date: June 1st, 2014
Name of booking: David Gregory Conference

Participants as of June 13
Awaiting Confirmation *

Full Name University/Affiliation
Abiad, Aida Tilburg University
Alhevaz, Abdollah* Amirkabir University of Technology
Arav, Marina Georgia State University
Breen, Jane University of Manitoba
Brualdi, Richard A. University of Wisconsin - Madison
Cioaba, Sebastian University of Delaware
Deaett, Louis Quinnipac University
Eastman, Brydon Redeemer University College
Elzinga, Randall Royal Military College
Erdahl, Bob* Queen's University
Erdahl, Robert Queen's University
Fallat, Shaun University of Regina
Farrag, Abdel-Aziz Dalhousie University
Fiol, Miquel Angel Universitat Politecnica de Catalunya
Foniok, Jan University of Warwick
Godsil, Chris University of Waterloo
Haemers, Willem Tilburg university
Javed, Sana* Abdus Salaam School of Mathematical Sciences G.C university
Kirkland, Steve University of Manitoba
Klymchuk, Tetiana* Taras Shevchenko National University of Kyiv
Li, Weiqiang* University of Delaware
Maltais, Elizabeth University of Ottawa
Mollahajiaghaei, Mohsen The University of Western Ontario
Moorhouse, Eric University of Wyoming
Murty, Ram Queen's University
Newman, Mike University of Ottawa
Pichugina, Oksana Brock University
Pirzada, Shariefuddin* University of Kashmir
Rayan, Steven University of Toronto
Roberson, David Nanyang Technological University
Shaked-Monderer, Naomi The Max Stern Yezreel Valley College
Tait, Michael University of California, San Diego
Tardif, Claude Royal Military College of Canada
Tsiovkina, Ludmila Krasovsky Institute of Mathematics and Mechanics
van Dam, Edwin Tillburg University
van der Holst, Hein Georgia State University
Vander Meulen, Kevin Redeemer University College
Wehlau, David Queen's University
Williford, Jason University of Wyoming