Skip to content
Texas A&M University
Mathematics

Events for 03/26/2021 from all calendars

Teaching Online Departmental Open Forum

iCal  iCal

Time: 12:00PM - 1:00PM

Location: Zoom

Speaker: Vanessa Coffelt & Justin Cantu, Texas A&M University

Description: All forums will be from 12:00 pm to 1:00 pm. The topic will be emailed to faculty the week prior to the forum. We will use the following Meeting ID: 979 6560 9771, and will send out the password in the emails.


Noncommutative Geometry Seminar

iCal  iCal

Time: 1:00PM - 2:00PM

Location: Zoom 951 5490 42

Speaker: Dan Voiculescu, University of California, Berkeley

Title: Around the Quasicentral Modulus

Abstract: The quasicentral modulus is a numerical invariant associated with a n-tuple of Hilbert space operators and a normed ideal of compact operators. It plays a key role in perturbations of n-tuples of operators and invariance of absolutely continuous spectra results. The talk will be about new results on the quasicentral modulus and commutants mod normed ideals. This will include exact formulas for the quasicentral modulus in fractional dimension and for hybrid perturbations. I will then talk about commutants mod normed ideals for compact differentiable manifolds with boundary and the K-theory exact sequence for their Calkin algebras for connected sums of manifolds.

URL: Event link


Mathematical Physics and Harmonic Analysis Seminar

iCal  iCal

Time: 2:00PM - 2:50PM

Location: Zoom

Speaker: Sergei Tabachnikov, Penn State

Title: Flavors of bicycle mathematics

Abstract: This talk concerns a naive model of bicycle motion: a bicycle is a segment of fixed length that can move so that the velocity of the rear end is always aligned with the segment. Surprisingly, this simple model is quite rich and has connections with several areas of research, including completely integrable systems. Here is a sampler of problems that I hope to touch upon: 1) The trajectory of the front wheel and the initial position of the bicycle uniquely determine its motion and its terminal position; the monodromy map sending the initial position to the terminal one arises. This mapping is a Moebius transformation, a remarkable fact that has various geometrical and dynamical consequences. 2) The rear wheel track and a choice of the direction of motion uniquely determine the front wheel track; changing the direction to the opposite, yields another front track. These two front tracks are related by the bicycle (Backlund, Darboux) correspondence, which defines a discrete time dynamical system on the space of curves. This system is completely integrable and it is closely related with another, well studied, completely integrable dynamical system, the filament (a.k.a binormal, smoke ring, local induction) equation. 3) Given the rear and front tracks of a bicycle, can one tell which way the bicycle went? Usually, one can, but sometimes one cannot. The description of these ambiguous tire tracks is an open problem, intimately related with Ulam's problem in flotation theory (in dimension two): is the round ball the only body that floats in equilibrium in all positions? This problem is also related to the motion of a charge in a magnetic field of a special kind. It turns out that the known solutions are solitons of the planar version of the filament equation.


Algebra and Combinatorics Seminar

iCal  iCal

Time: 3:00PM - 4:00PM

Location: Zoom

Speaker: Zixia Song, University of Central Florida

Title: Hadwiger’s Conjecture

Abstract: Hadwiger's conjecture from 1943 states that for every integer t, every graph either can be t-colored or has a subgraph that can be contracted to the complete graph on t+1 vertices. This is a far-reaching generalization of the Four-Color Theorem and perhaps the most famous conjecture in graph theory. In this talk we will survey the history of Hadwiger's conjecture and the main ideas of recent results.