May 23, 2018

August 2-4, 2011
Workshop on Positivity
Positivity in the classification of operator algebras and dynamical systems,
in finite- and infinite-dimensional linear algebra, and its outgrowths

hosted by the Fields Institute,
held at the University of Toronto, Bahen Building, Room 1200 Map

Organizer: Thierry Giordano, Vladimir Pestov
Online registration is now closed.
On-site Registration available Aug. 2.
Schedule Abstracts Participant List
Abtract Submissions Accommodation Resources Toronto Resources


The notion of positivity, whose study is motivated by deep questions in operator algebras, has important applications in a large number of areas of mathematics, for example

  • connections among commutative algebra, positive multiplications of polynomials and characters (of compact groups), partially ordered abelian groups (especially dimension groups), and special random walks
  • C*-algebra theory and in the classification of compact group actions on AF algebras;
  • classification in measure-theoretic ergodic theory, especially dealing with approximate transitivity and matrix-valued random walks
  • classification in topological ergodic theory, via ordered K0-theory

These research directions and their outgrowths have been and remain particularly active in Canada, with David Handelman having been a major contributor over past decades. In particular, he has established profound connections between these areas. The goal of this workshop, timed to mark David's 60th birthday, is to present and further develop these connections.

Invited Speakers:

B. Blackadar (University of Nevada, Reno)
M. Boyle (University of Maryland)
M.-D. Choi (University of Toronto)
G. A. Elliott (University of Toronto)
V. Kaimanovich (University of Ottawa)
D. Kerr (Texas A&M)
B. Marcus (University of British Columbia)
J. Renault (Université d'Orléans)
B. Reznick (University of Illinois at Urbana-Champaign)
K. Schmidt (University of Vienna)
C. Skau (Norwegian University of Science & Technology)
A. Toms (Purdue University)


Tuesday, August 2 (Bahen Room 1200)
9:45- 10:30 On-site Registration and Morning Coffee
10:30-11:30 George Elliott, University of Toronto
Not every functor is manifestly covariant
11:30-12:30 Bruce Blackadar, University of Nevado, Reno
Recent results on semiprojectivity
12:30-14:30 Lunch Break
14:30-15:30 Andrew Toms, Purdue University
The Cuntz semigroup, mean dimension, and the structure of crossed products
15:30-16:00 Coffee Break
16:00-16:45 Aaron Tikuisis, University of Toronto
Representing dimension groups in real vector spaces
16:45-17:15 Wadii Hajji, University of Ottawa
Compact inverse semigroup representation
17:30-18:30 Reception at the Fields Institute
Wednesday, August 3 (Bahen Room 1200)
9:00-9:30 Morning Coffee
9:30-10:30 Mike Boyle, University of Maryland
The Generalized Spectral Conjecture, and the Williams Conjecture
for positive matrices over unital subrings of the reals
10:30-11:00 Coffee Break
11:00-12:00 Vadim Kaimanovich, University of Ottawa
Rate of escape on groupoids
12:00-12:30 Charles Starling, University of Ottawa
Finite Group Actions on C*-algebras Associated to Tilings
12:30-14:00 Lunch Break
14:00-15:00 Brian Marcus, University of British Columbia
A complex Hilbert metric with application to entropy of Hidden
Markov Chains
15:00-15:30 Termeh Kousha, University of Ottawa
Asymptotic behavior and moderate deviation principle for the maxi-
mum of a Dyck path
15:30-16:00 Coffee Break
16:00-17:00 Klaus Schmidt, University of Vienna
Entropy and periodic points of algebraic group actions
18:30- Banquet (John's Italian Cafe, 27 Baldwin St.)
Thursday, August 4 (Bahen Room 1200)
9:00-9:30 Morning Coffee
9:30-10:30 Jean Renault, Université d'Orléans
Conditionally negative type functions on groupoids
10:30-11:00 Coffee Break
11:00-12:00 David Kerr, Texas A&M University
Topological dynamics and crossed products: finite approximation and
12:00-12:30 Catalin Rada, University of Ottawa
On crossed products by Z of algebras arising from reduced free group
12:30-14:00 Lunch Break
14:00-15:00 Man-Duen Choi, University of Toronto
Positive linear maps through quantum computers
15:00-15:30 Ion Nechita, University of Ottawa and CNRS
Positivity as a tool in quantum entanglement theory
15:30-16:00 Coffee Break
16:00-17:00 Christian Skau, Norwegian University of Science & Technology
Toeplitz flows and their K-theory

Financial support:

Partial financial support will be available for graduate students and postdocs. The deadline to apply was Friday May 27 and the funding decisions have been made.

List of Confirmed Participants as of July 25, 2011:

Full Name University Name
Al-Nuwairan, Muneerah University of Ottawa
Belinschi, Serban University of Saskatchewan
Blackadar, Bruce University of Nevada, Reno
Boyle, Mike University of Maryland
Choi, Man-Duen University of Toronto
Elliott, George University of Toronto
Giordano, Thierry University of Ottawa
Hajji, Wadii University of Ottawa
Handelman, David University of Ottawa
Ivanescu, Cristian MacEwan University and University of Alberta
Kaimanovich, Vadim University of Ottawa
Katz, Alexander A. St. John's University
Kerr, David Texas A&M University
Kousha, Termeh University of Ottawa
Li, Zhiqiang Fields Institute
Marcus, Brian University of British Columbia
Nawata, Norio Kyushu University
Nechita, Ion University of Ottawa
Pestov, Vladimir University of Ottawa
Rada, Catalin University of Ottawa
Renault, Jean University of Orleans
Reznick, Bruce University of Illinois at Urbana-Champaign
Schmidt, Klaus University of Vienna
Skau, Christian Norwegian University of Science & Technology
Starling, Charles University of Ottawa
Tekle, Yohannes Ivytech Community College
Tikuisis, Aaron University of Toronto
Toms, Andrew Purdue University
Viola, Maria Grazia Lakehead University-Orillia
Kaimanovich, Vadim University of Ottawa
Lawrence, John W. University of Waterloo