Penelope Evelyn Haxell is a Canadian mathematician who works as a professor in the department of combinatorics and optimization at the

University of Waterloo The University of Waterloo (UWaterloo, UW, or Waterloo) is a public research university with a main campus in Waterloo, Ontario Waterloo is a city in the Canadian province of Ontario. It is one of three cities in the Regional Municipality ...

. Her research interests include

extremal combinatorics Extremal combinatorics is a field of combinatorics, which is itself a part of mathematics. Extremal combinatorics studies how large or how small a collection of finite objects (numbers, graphs, vectors, sets, etc.) can be, if it has to satisfy ce ...

and

graph theory In mathematics, graph theory is the study of ''graphs'', which are mathematical structures used to model pairwise relations between objects. A graph in this context is made up of '' vertices'' (also called ''nodes'' or ''points'') which are conne ...

Education and career

Haxell earned a bachelor's degree in 1988 from the University of Waterloo, and completed a doctorate in 1993 from the

University of Cambridge , mottoeng = Literal: From here, light and sacred draughts. Non literal: From this place, we gain enlightenment and precious knowledge. , established = , other_name = The Chancellor, Masters and Schola ...

under the supervision of

Béla Bollobás Béla Bollobás FRS (born 3 August 1943) is a Hungarian-born British mathematician who has worked in various areas of mathematics, including functional analysis, combinatorics, graph theory, and percolation. He was strongly influenced by Paul E ...

. Since then, she has worked at the University of Waterloo, where she was promoted to full professor in 2004.

Research

Haxell's research accomplishments include results on the

Szemerédi regularity lemma Szemerédi's regularity lemma is one of the most powerful tools in extremal graph theory, particularly in the study of large dense graphs. It states that the vertices of every large enough graph can be partitioned into a bounded number of parts so ...

hypergraph In mathematics, a hypergraph is a generalization of a graph in which an edge can join any number of vertices. In contrast, in an ordinary graph, an edge connects exactly two vertices. Formally, an undirected hypergraph H is a pair H = (X,E) wh ...

generalizations of

Hall's marriage theorem In mathematics, Hall's marriage theorem, proved by , is a theorem with two equivalent formulations: * The combinatorial formulation deals with a collection of finite sets. It gives a necessary and sufficient condition for being able to select a di ...

(see Haxell's matching theorem), fractional graph

packing problems Packing problems are a class of optimization problems in mathematics that involve attempting to pack objects together into containers. The goal is to either pack a single container as densely as possible or pack all objects using as few conta ...

, and strong coloring of graphs.

Recognition

Haxell was the 2006 winner of the

Krieger–Nelson Prize The Krieger–Nelson Prize is presented by the Canadian Mathematical Society in recognition of an outstanding woman in mathematics. It was first awarded in 1995. The award is named after Cecilia Krieger and Evelyn Nelson (mathematician), Evelyn Nels ...

of the

Canadian Mathematical Society The Canadian Mathematical Society (CMS) (french: Société mathématique du Canada) is an association of professional mathematicians dedicated to the interests of mathematical research, outreach, scholarship and education in Canada. It serves the ...

References

{{DEFAULTSORT:Haxell, Penny Year of birth missing (living people) Living people Canadian mathematicians Women mathematicians University of Waterloo alumni Alumni of the University of Cambridge Academic staff of the University of Waterloo Graph theorists Place of birth missing (living people)