André Boivin (1955-2014) passed away at University Hospital on Friday, October 17, 2014, as a result of heart failure.

Professor Boivin completed his PhD at the Université de Montréal in 1984 under the direction of Paul Gauthier. He came to the University of Western Ontario as an Assistant Professor in 1986, after holding postdoctoral fellowships at UCLA and University College, London. He was promoted to Associate Professor in 1991, and then to Professor in 2004. He was appointed as Chair of Western's Department of Mathematics in 2011.

His research specialties were complex analysis and approximation theory, and he was the author of multiple papers in these areas. He gave tireless service to granting agencies and selection committees in Québec and Ontario, and was a frequent conference organizer.

He served with distinction as Graduate Student Chair before becoming Chair of the Department, and supervised many graduate students during the course of his career at Western. Caring, warmth and passion were the hallmarks of his relationships with students and colleagues.

André Boivin is survived by his wife Yinghui Jiang, son Alexandre, daughter Melanie and step son JP. He was well loved and respected by his colleagues, students and coworkers throughout the University, and he will be sorely missed.

Each week the Department of Mathematics hosts a wide variety of seminars and events. For a comprehensive list of events, please consult our departmental calendar.

In this talk, we will show a way to develop category theory in Univalent foundations. As it turns out, the naive reformulation of the standard axioms from set theory leads to a rather ill-behaved notion. We show how it can be refined. We also observe that for these redefined categories, two concepts of equivalence and isomorphism are the same.

Operator theory on spaces of holomorphic functions has undergone a rapid development in the last several decades. It started with spaces of functions holomorphic on the unit disk in the complex plane and it kept developing into higher dimensions. Particularly well studied cases are operators acting on Bergman spaces on the ball and polydisk. We use $\overline\partial$-techniques to study compactness of Hankel and Toeplitz operators on Bergman spaces on pseudoconvex domains in $\mathbb{C}^n$. This is joint work with Sonmez Sahutoglu.

The classifying space $BG$ of a group $G$ can be filtered by a sequence of subspaces $B(q,G)$, using the descending
central series of free groups. The smallest subspace in this filtration is $B(2,G)$ which is obtained from commuting elements in
the group. When $G$ is finite describing these subspaces as homotopy colimits is convenient to study the cohomology,
and also generalized cohomology theories. I will describe the complex $K$-theory of $B(2,G)$ modulo torsion, and discuss
examples where non-trivial torsion part appears.

Let $\mathcal{H} \subset \mbox{Hol}(\mathbb{D})$ be a Hilbert space of analytic functions. A finite positive Borel measure $\mu$ on $\mathbb{D}$ is a Carleson measure for $\mathcal{H}$ if
\[
\|f\|_{L^2(\mu)} \leq C \|f\|_{\mathcal{H}}, \qquad f \in \mathcal{H}.
\]
Equivalently, we can say that $\mathcal{H}$ embeds in $L^2(\mu)$. In 1962, Carleson solved the corona problem. But, besides solving this difficult problem, he opened many other venues of research. For example, he characterized such measures (now called Carleson measures) for the Hardy-Hilbert space $H^2$. However, the same question perfectly makes sense for any other Hilbert space of functions. We will discuss Carleson measures for the classical Dirichlet space $\mathcal{D}$.