## Contact Info

Pure MathematicsUniversity of Waterloo

200 University Avenue West

Waterloo, Ontario, Canada

N2L 3G1

Departmental office: MC 5304

Phone: 519 888 4567 x43484

Fax: 519 725 0160

Email: puremath@uwaterloo.ca

Thursday, February 9, 2023 — 2:30 PM EST

**Luke MacLean, Department of Pure Mathematics, University of Waterloo**

**"Effectively closed sets - Part V"**

An effectively closed set (or $\Pi^0_1$ class) in Baire space $\omega^\omega$ is the set $[T]$ of infinite branches through a computable tree $T$. This semester in the computability seminar, we will be studying $\Pi^0_1$ classes from Cenzer \& Remmel's textbook. This week we will continue proving basis theorems and take a brief detour into Martin-Lof randomness.

MC 5403

Thursday, February 9, 2023 — 2:30 PM EST

**Rasul Shafikov, Western University**

**"Lagrangian embeddings, rational convexity, and approximation"**

A celebrated theorem of Duval and Sibony characterizes rationally convex real submanifolds in complex Euclidean spaces as those isotropic with respect to a Kahler form. I will discuss how the results in symplectic geometry can be used to obtain some new results in the approximation theory.

MC 5417

Thursday, February 9, 2023 — 4:00 PM EST

**Camila Sehnem, Department of Pure Mathematics, University of Waterloo**

**"C*-envelopes and semigroup C*-algebras"**

University of Waterloo

200 University Avenue West

Waterloo, Ontario, Canada

N2L 3G1

Departmental office: MC 5304

Phone: 519 888 4567 x43484

Fax: 519 725 0160

Email: puremath@uwaterloo.ca

University of Waterloo

University of Waterloo

43.471468

-80.544205

200 University Avenue West

Waterloo,
ON,
Canada
N2L 3G1

The University of Waterloo acknowledges that much of our work takes place on the traditional territory of the Neutral, Anishinaabeg and Haudenosaunee peoples. Our main campus is situated on the Haldimand Tract, the land granted to the Six Nations that includes six miles on each side of the Grand River. Our active work toward reconciliation takes place across our campuses through research, learning, teaching, and community building, and is centralized within our Office of Indigenous Relations.