Skip to content
# Events for 04/10/2020 from all calendars

## Several Complex Variables Seminar

## Mathematical Physics and Harmonic Analysis Seminar

## Mathematical Physics and Harmonic Analysis Seminar

## Banach and Metric Space Geometry Seminar

**Time: ** 10:20AM - 11:10AM

**Location: ** Zoom

**Speaker: **Tanuj Gupta, Texas A&M University

**Title: ***Student reading seminar on reproducing kernels*

**Abstract: **More properties of reproducing kernels

https://tamu.zoom.us/j/930289270

Meeting ID: 930 289 270

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

**Location: ** BLOC 628

**Speaker: **Braxton Osting, University of Utah

**Title: ***CANCELLED*

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

**Location: ** Zoom seminar

**Speaker: **Gregory Berkolaiko, Texas A&M University

**Title: *** Zoom Seminar: Global extrema of dispersion relation of tight-binding models*

**Abstract: **Tight-binding approximation is frequently used in physics to analyze
wave
propagation through periodic medium. Its Floquet–Bloch transform is a
compact graph with a parameter-dependent operator defined on it. The
graph of the eigenvalues as functions of parameters is called the
dispersion
relation. Extrema (minima and maxima) of the n-th eigenvalue give rise
to band edges: endpoints of intervals supporting continuous spectrum and
therefore allowing wave propagation. Locating the extrema can be
difficult
in general; there are examples where extrema occur away from the set of
parameters with special symmetry.
In this talk we will show that a large family of tight-binding models
have a curious property: there is a local condition akin to the second
derivative test that detects if a critical point is a global (sic!)
extremum. Under some additional assumptions (time-reversal
and dimension 3 or less), we show that any local extremum of a given
sheet of the dispersion relation is in fact the global extremum.
Based on a joint project with Yaiza Canzani, Graham Cox, Jeremy
Marzuola.

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

**Location: ** BLOC220

**Speaker: **Yury Makarychev, Toyota Technological Institute at Chicago and Univ. of Chicago

**Title: ***canceled due to the COVID-19 pandemic*