Israel Halperin was a pioneer of mathematical research in Canada, and was the founder of a group of researchers in operator algebras and operator theory at the University of Toronto. His influence led eventually to the development of a very strong group in the field across Canada. He also was responsible for starting an annual meeting in the field, now called the Canadian Operator Symposium (COSy), which is held at various universities across Canada. He was also well known for his work on humanitarian issues.
In 1979, in honour of Halperin on his retirement, a prize was established called the Israel Halperin Prize. See the original document. The Israel Halperin Prize is awarded every five years for outstanding work in operator algebras or operator theory to members of the Canadian mathematical community who are within ten years of receipt of their doctorate.
Past Winners
1980 Man Duen Choi University of Toronto 1985 Kenneth Davidson University of Waterloo David Handelman University of Ottawa 1990 Ian Putnam Dalhousie University 1995 Nigel Higson Pennsylvania State University 2000 Guihua Gong University of Puerto Rico Alexandru Nica University of Waterloo 2010 Andrew Toms York University 2015 Serban Belinschi Queen's University Zhuang Niu University of Wyoming 2020 Matthew Kennedy University of Waterloo Aaron Tikuisis University of Ottawa 2025 Michael Hartz Universitat des Saarlandes Christopher Schafhauser University of Nebraska, Lincoln
Michael Hartz
Michael Hartz earned his Ph.D. at the University of Waterloo in 2016 under the supervision of Kenneth Davidson. His first paper, as a Master's student of J. Eschmeier, established the rigidity of certain operator algebras associated to radical ideals, answering a conjecture of Davidson, Ramsey and Shalit. Hartz's work resolved two of the most important open problems in the study of commutative operator algebras: with Aleman, McCarthy and Richter, he characterized interpolating sequences for multipliers of the Drury-Arveson space; and he established the column-row property for complete Nevanlinna-Pick spaces, which has many striking consequences. He has made many deep contributions to operator theory and operator algebras. In 2020, Michael was awarded the Barbara and Jaroslav Zemanek Prize in functional analysis by the Institute of Mathematics of the Polish Academy of Science. He is currently a Professor at Universitat des Saarlandes in Saarbrucken.
Christopher Schafhauser
Christopher Schafhauser earned his Ph.D. in 2015 from the University of Nebraska under the supervision of Allan Donsig and David Pitts. As a postdoc iat U. Waterloo and then York U., he established himself a new force in the field of C*-algebras with several major results: a new, concise proof of the Tikuisis-White-Winter Theorem, embedding every separable exact C*-algebra with amenable trace and UCT into a simple monotracial AF algebra, and a characterization of the ideal property for crossed products (with M. Kennedy). Schafhauser was a critical contributor to the conceptual and self-contained C*-algebra classification theorem of Carrion et al. More recently, he established a beautiful KK-rigidity theorem for simple nuclear C*-algebras. In 2024, Chris was awarded the Barbara and Jaroslav Zemanek Prize in functional analysis by the Institute of Mathematics of the Polish Academy of Science. Schafhauser is currently Associate Professor of Mathematics at the University of Nebraska-Lincoln.
Matthew Kennedy
Matthew Kennedy received his doctorate in 2011 from the University of Waterloo under the supervision of Kenneth Davidson. In 2011, he was appointed Assistant Professor at Carleton University. He moved to the University of Waterloo in 2015, and a year later was promoted to the rank of Associate Professor. Kennedy, with Davidson, introduced and pioneered the development of a non-commutative generalization of Choquet theory. This was based in part on these authors' solution of a fifty-year-old problem of Arveson (establishing the existence of sufficiently many boundary representations). Kennedy carried this further, developing (with Shamovich) a notion of non-commutative Bauer simplex, with applications to dynamics. Kennedy, partially in collaboration with Kalantar, Breuillard, and Ozawa, definitively analyzed the property of a discrete group that its reduced C*-algebra is simple (C*-simplicity)---providing several different characterizations. These authors also characterized when the C*-algebra has a unique trace, which, surprisingly, was not equivalent to C*-simplicity.
Aaron Tikuisis
Aaron Tikuisis received his doctorate in 2011 from the University of Toronto under the supervision of George Elliott. Following a postdoctoral position at the University of Muenster, Tikuisis was appointed Lecturer at the University of Aberdeen in 2013 where for two years he also held an NSERC Postdoctoral Fellowship. He was promoted to the rank of Reader in 2016, and in 2017 moved to the University of Ottawa as Associate Professor. Tikuisis is cited for two major contributions to the classification of simple C*-algebras. First, in collaboration with White and Winter, he established the redundancy of the axiom of quasidiagonality of traces in the K-theoretical classification of Elliott, Gong, Lin, and Niu for simple separable amenable C*-algebras of finite nuclear dimension (satisfying the Universal Coefficient Theorem, possibly also redundant). At the same time this answered a forty-year-old question of Rosenberg---is the condition that a discrete group be quasidiagonal in its regular representation necessary, as well as sufficient (as Rosenberg proved), for amenability? Second, in collaboration with Castillejos, Evington, White, and Winter, he showed that the axiom of finite nuclear dimension is equivalent to another axiom, Jiang-Su stability, which is enormously easier to verify in examples.