Colloquium Coordinator: Debraj Chakrabarti
Because there might be a time delay in updating the webpage, please always check with the Coordinator for the available dates.
Typical Colloquium Talks are Thursday, 4:00–4:50pm, in person in Room 227 of Pearce Hall.
Special media arrangement such as virtual, or HyFlex format, if available,
is indicated under Remark.
The following table gives the information for all colloquium activities (on any day), and each Thursday event that is open to the public.
For Graduate Student Seminar (GSS) schedule on Tuesdays, please click here.
| Date | Speaker | Title (Scroll down for Abstract) | Remark |
|---|---|---|---|
| 10/2/2025 | Dept Meeting | 10/9/2025 | Graduate Course Exhibition | CMU Faculty | 10/16/2025 | Spl Dept Meeting | 10/23/2025 | Jiahong Wu (Univ of Notre Dame) | Stability, Interaction, and Enhanced Dissipation in Fluids | 10/30/2025 | 11/06/2025 | 11/13/2025 | David Miyamoto (Queen's University, Kingston ON) | Lie algebras of quotient groups | 11/20/2025 | 11/27/2025 | 12/04/2025 | 1/08/2026 | 1/15/2026 | 1/22/2026 | 2/05/2026 | 2/12/2026 | 2/19/2026 | 2/26/2026 | 3/05/2026 | 3/12/2026 | 3/19/2026 | 3/26/2026 | 04/02/2026 | 04/09/2026 | 04/16/2026 | 04/23/2026 | 04/30/2026 | 05/07/2026 |
Speaker: David Miyamoto
Title: Lie Algebras of Quotient Groups
Abstract: Given a Lie group $G$ and a normal subgroup $H$, if $H$ Is closed in $G$ then the quotient $G/H$ is a Lie group with Lie algebra $\mathrm{Lie}(G)/\mathrm{Lie}(H)$. This result fails at a basic level if H is not closed in $G$: in this case the quotient is not even a manifold. It could even be topologically trivial, such as the irrational torus $\mathbb{R}/(\mathbb{Z}+a\mathbb{Z})$, for $a$ irrational.
I will show that if we instead view $G/H$ as a diffeological group, a generalization of a Lie group that preserves notions of smoothness at the cost of local models, we have $\mathrm{Lie}(G/H) =\mathrm{Lie}(G)/\mathrm{Lie}(H)$. unconditionally. I will also discuss conditions under which this holds for infinite-dimensional Lie groups.
Speaker: Jiahong Wu
Title: Stability, Interaction, and Enhanced Dissipation in Fluids
Abstract: This talk presents recent results on the stability of physically relevant steady-state solutions in fluid dynamics, focusing on the Boussinesq system near hydrostatic equilibrium and the magnetohydrodynamic equations near a background magnetic field. These systems involve only partial dissipation and traditional stability analysis simply fails. Our approach exploits two forms of enhanced dissipation: one due to the steady-state itself and the other from coupling and interaction within components of the system. Mathematically, the equations governing perturbations can be systematically converted into anisotropic, often degenerate, wave equations. These wave structures reflect the enhanced dissipation and enable us to design a systematic and effective approach for these otherwise seemingly impossible stability problems.