Location and Time: Minard 118 at 3:00 PM (Refreshments at 2:30 in TBD)

*Special Colloquia or Tri-College Colloquia venues and times may vary, please consult the individual listing.

Tuesday, February 11       

Teemu Saksala , NCSU

Geometric Inverse Problems Arising from Hyperbolic PDEs

Abstract: : In this talk I will survey the classical Boundary Control method, originally developed by Belishev and Kurylev, which can be used to reduce an inverse problem for a hyperbolic equation, on a complete Riemannian manifold, to a purely geometric problem involving the so-called travel time data. For each point in the manifold the travel time data contains the distance function from this point to any point in a fixed a priori known closed observation set. If the Riemannian manifold is closed then the observation set is a closure of an open and bounded set, and in the case of a manifold with boundary the observation set is an open subset of the boundary. We will survey many known uniqueness and stability results related to the travel time data.

Tuesday, February 25

*Special Tri-College Colloquium at Concordia
Talk: Integrated Science Center 301 (Refreshments: Integrated Science Center 362)

Torin Greenwood, NDSU

Title: Coloring the integers while avoiding monochromatic arithmetic progressions

Abstract: Consider coloring the positive integers either red or blue one at a time in order.  Van der Waerden's classical theorem states that no matter how you color the integers, you will eventually have k equally spaced integers all colored the same for any k.  But, how can we minimize the number of times k equally spaced integers are colored the same?  Even for k = 3, this question is unsolved.  We will discuss progress towards proving an existing conjecture by leveraging a connection to coloring the continuous interval [0,1]. Our strategy relies on identifying classes of colorings with permutations and then using mixed integer linear programming.  Joint work with Jonathan Kariv and Noah Williams.

Tuesday, April 15   

Leigh Foster, U of Waterloo

The squish map and the SL_(2+) dimer model

Abstract:  A pile of cube-shaped boxes shoved into the corner of a room can be represented as a plane partition (a 2D array of numbers that weakly decreases in both rows and columns). This can be approximated by a "coarser" plane partition, where each new box is a 2x2x2 cube. We relate this coarsening operation to the squish map and exhibit a related measure-preserving map between the 2-periodic single dimer model on the honeycomb graph and a particular instance of Kenyon's SL_2 double dimer model on a coarser honeycomb graph. We also specialize this map to exhibit new criterion for the signed-tilability of a closed region on the honeycomb graph. Finally, we present preliminary work on the SL_3 dimer model, suggesting a similar connection between a 3-periodic single dimer configuration and an instance of the triple dimer model.

Tuesday, April 29

*Special Tri-College Colloquium at NDSU

Tbd, Msum

Title: TBD

Abstract:TBD

Thursday, May 8   

Paul Hagelstein, Baylor U

Current developments in the theory of differentiation of integrals

Abstract:  TBD