# Events for 09/29/2023 from all calendars

## Mathematical Physics and Harmonic Analysis Seminar

**Time: ** 1:50PM - 2:50PM

**Location: ** BLOC 302

**Speaker: **Yannick Sire, Johns Hopkins

**Title: ***Harmonic maps between singular spaces*

**Abstract: **After reviewing briefly the classical theory of harmonic maps between smooth manifolds, I will describe some recent results related to harmonic maps with free boundary, emphasizing on two different approaches based on recent developments by Da Lio and Riviere. This latter approach allows in particular to give another formulation which is well-suited for such maps between singular spaces. After the works of Gromov, Korevaar and Schoen, harmonic maps between singular spaces have been instrumental to investigate super-rigidity in geometry. I will report on recent results where we introduce a new energy between singular spaces and prove a version of Takahashi’s theorem (related to minimal immersions by eigenfunctions) on RCD spaces.

## Algebra and Combinatorics Seminar

**Time: ** 3:00PM - 4:00PM

**Location: ** BLOC 302

**Speaker: **Youngho Yoo, TAMU

**Title: ***Path odd-covers of graphs*

**Abstract: **We study the minimum number of paths needed to express the edge set of a given graph as the symmetric difference of the edge sets of the paths. This problem sits in between Gallai's path decomposition problem and the linear arboricity problem. It is also motivated by the study of the diameter of partition polytopes, and we adapt some techniques therein to prove bounds on the path odd-cover number of graphs. Joint work with Steffen Borgwardt, Calum Buchanan, Eric Culver, Bryce Frederickson, and Puck Rombach.

## Geometry Seminar

**Time: ** 4:00PM - 5:00PM

**Location: ** BLOC 302

**Speaker: **Klemen Sivic, University of Ljubljana

**Title: ***Applications of Borel fixed point theorem to linear algebra*

**Abstract: **The Borel fixed point theorem says that an action of a solvable algebraic group on a projective variety has a fixed point. In the talk we will show how this theorem can help us to determine the upper bound on dimension of certain matrix spaces. In particular, we will consider spaces of matrices with bounded number of eigenvalues and spaces of matrices with commutators of bounded rank.