Media Release – January 20, 2021
Canadian Mathematical Society

Dr. Luke Postle to Receive the 2021 Coxeter-James Prize

OTTAWA, ON – The Canadian Mathematical Society (CMS) is pleased to announce that Dr. Luke Postle (University of Waterloo) has been named the recipient of the 2021 Coxeter-James Prize for his work in the area of graph theory.  Dr. Postle will receive his award and present a prize lecture during the CMS Winter Meeting in December 2021.

Dr. Luke Postle is an exceptional young researcher in structural graph theory, earning his Ph.D. in 2012 in the Department of Mathematics at the Georgia Institute of Technology. He quickly earned a strong international reputation by using a broad and innovative range of tools to solve old and deep problems in combinatorics. He made several significant contributions, to difficult, important, and long-standing open problems in graph colouring.

Dr. Postle established himself as a leading researcher in graph theory. He published in the top journals such as Journal of Combinatorial Theory B (JCTB), Combinatorica, and Journal of Graph Theory, and gave talks at conferences and universities around the world.  He made ground-breaking progress on many famous conjectures in graph colouring, including Hadwiger’s Conjecture, the Goldberg-Seymour Conjecture, Reed’s Conjecture, and Jaeger’s Conjecture.

Luke Postle has launched a new paradigm in graph coloring with his introduction of a new generalization of coloring. Namely in 2015, Luke Postle and his collaborator Zdenek Dvorak introduced correspondence colouring in article published in JCTB, now referred to as DP-colouring by the community after their surnames. Correspondence colouring is a generalization of list colouring. List colouring, itself a generalization of colouring, was first introduced by Erdos, Rubin and Taylor in the 1970s and is now the subject of over a thousand journal articles. In list colouring each vertex has its own list from which it must be coloured. In correspondence colouring, they abstracted this by removing any `global’ notion of colour and rather only using a `local’ notion, individual to each vertex. Such a generalization can actually be used for inductive purposes to solve list colouring problems, namely they used the concept to solve a 15-year-old conjecture that planar graphs without 4 to 8 cycles are 3-list-colourable. Since then, their article has garnered 86 citations in 3 years according to Google Scholar and indeed the article is listed on JCTB’s own website as its most cited article published since January 2018. Correspondence colouring has been used both to solve open colouring problems and been studied in its own right as a natural form of colouring. For example, correspondence colouring proved a key ingredient in Luke Postle’s research on Reed’s conjecture.

Dr. Postle is currently an Associate Professor in the Department of Combinatorics and Optimization at the University of Waterloo. Since joining Waterloo in 2014, he was awarded a Tier 2 Canada Research Chair and an Early Researcher Award from the government of Ontario.

About the Coxeter-James Prize

The Coxeter-James Prize was inaugurated in 1978 to recognize young mathematicians who have made outstanding contributions to mathematical research. The award is named for two former CMS presidents, Donald Coxeter, who is recognized as one of the world’s best geometers, and Ralph Duncan James, who was a great contributor to mathematical development in Canada.

For information about past recipients, visit:

About the Canadian Mathematical Society (CMS)

The CMS is the main national mathematical organization whose goal is to promote and advance the discovery, learning and application of mathematics. The Society’s activities cover the whole spectrum of mathematics including: scientific meetings, research publications, and the promotion of excellence in mathematics competitions that recognize outstanding student achievements.

For more information, please contact:

Prof. Victor LeBlanc (Ottawa)
Chair, CMS Research Committee
Canadian Mathematical Society
Or Prof. Javad Mashreghi (Laval)
Canadian Mathematical Society