Logic seminar: Mushfeq Khan
Mar 16 @ 2:30 pm – 3:30 pm
Colloquium: Andreas Weinmann (Hochschule Darmstadt and Helmholtz Center Munich) @ Keller 401
Mar 16 @ 3:30 pm – 4:30 pm

Speaker: Andreas Weinmann (Hochschule Darmstadt and Helmholtz Center Munich)

Title: Variational methods for the restauration of manifold-valued images and data

Abstract: Nonlinear manifolds appear as data spaces in various applications. One example in image processing is diffusion tensor imaging, where the data sitting in every voxel is a positive matrix representing the diffusibility of water molecules measured at the corresponding spatial location. Another example is color image processing, where instead of the RGB representation often other formats such as HSI or HSV are used which employ a circle to represent the hue of a color. A third example are registration problems (e.g., between a camera and an ultrasound devise) where time series of euclidean motions appear. Since the measured data is often noisy, regularization of these nonlinear data is necessary. In this talk, we propose algorithms for the variational regularization of manifold-valued data using non-smooth functionals. In particular, we deal with algorithms for TV regularization and with higher order methods including the TGV denoising of manifold-valued data. We present concrete applications in medical imaging tasks.

Undergrad Seminar
Mar 22 @ 3:00 pm – 4:00 pm
Logic seminar: Amenability and Symbolic Dynamics @ Keller Hall 314
Mar 23 @ 2:30 pm – 3:30 pm

David Webb will continue to discuss results from Adam Day’s paper on amenability and symbolic dynamics.

Colloquium: Christopher Marks (Cal. State Chico)
Mar 23 @ 3:30 pm – 4:30 pm

Speaker: Christopher Marks (Cal. State Chico)

Title: Vector-valued modular forms and CM Jacobians

Abstract: In this talk, I will explain how vector-valued modular forms

may be used to compute explicitly periods of modular curves, and how the

application of this technique to noncongruence subgroups of the modular

group should soon yield new examples of Jacobians of modular curves with

complex multiplication (i.e., CM Jacobians).

Logic seminar: David Ross
Apr 6 @ 2:30 pm – 3:30 pm

This week in the Logic Seminar in Keller 314, David Ross will give an easy proof of a slight extension of a result of Lagarias on the Diophantine equation

       $$ c(1/x_1+cdots+1/x_s)+b/(x_1 x_2cdots x_s)=a$$

The proof will be nonstandard, but really only require a sufficiently-saturated ordered field extension of $mathbb R$.

Undergraduate Seminar: Alex Schulte (Iowa State U.) @ Keller 402
Apr 12 @ 3:00 pm – 4:00 pm
Logic seminar: Mushfeq Khan @ Keller 314
Apr 13 @ 2:30 pm – 3:30 pm

Mushfeq Khan will coninue to speak on amenability and symbolic dynamics.  The focus will be the Ornstein-Weiss combinatorial
lemmas from Adam Day’s paper.