MenuEvents for 03/03/2023 from all calendars
Noncommutative Geometry Seminar
Time: 1:00PM - 2:00PM
Location: ZOOM
Speaker: Jinmin Wang , Texas A&M University
Title: Index pairing and quantitative control of scalar curvature
Abstract: In this talk, I will speak about an index theoretical approach to a series of Gromov’s questions related to positive scalar curvature. Our approach is to study the index pairing of the Dirac operator and vector bundles. The concrete construction of index pairing reveals a quantitative control of positive scalar curvature, which results from a new uncertainty principle for Fourier transforms. This is based on joint work with Zhizhang Xie and Guoliang Yu.
Student/Postdoc Working Geometry Seminar
Time: 1:00PM - 2:30PM
Location: BLOC 628
Speaker: Derek Wu, TAMU
Title: New border rank lower bounds for GL(V) invariant tensors II
Mathematical Physics and Harmonic Analysis Seminar
Time: 1:50PM - 2:50PM
Location: BLOC 302
Speaker: Alejandro Aceves, SMU
Title: On the Fractional nonlinear Schrödinger Equation
Abstract: The concept of the fractional Lapacian as it relates to Levi flights in comparison to Brownian motion appears in many applications in physics. In this talk we will present our work as it relates to optical physics, in particular in the nonlinear regime where both the discrete and the continuous versions are relevant.
Algebra and Combinatorics Seminar
Time: 3:00PM - 4:00PM
Location: BLOC 302
Speaker: Chun-Hung Liu, Texas A&M University
Title: Proper conflict-free coloring and maximum degree
Abstract: A conflict-free coloring of a hypergraph is a coloring on the vertices such that for every hyperedge, some color appears exactly once on the vertices of this edge. This notion is motivated by a frequency assignment problem of cellular networks and is a generalization of a number of variants of coloring notions of graphs. We prove a general upper bound for the number of colors for (proper) conflict-free coloring involving the maximum degree and rank. It provides improvements about linear coloring and star coloring of graphs with bounded maximum degree and addresses a conjecture of Caro, Petrusevski and Skrekovski on proper conflict-free coloring of graphs. They conjectured that for every d \geq 3, every connected graph with maximum degree at most d has a proper conflict-free coloring with d+1 colors. We prove that (1.655083+o(1))d colors suffice. We also prove that the fractional coloring version of this conjecture is asymptotically true. This is joint work with Daniel Cranston.
Geometry Seminar
Time: 4:00PM - 4:50PM
Location: BLOC 302
Speaker: Yen-Kheng Lim, Xiamen University Malaysia
Title: Solving physics problems from the perspective of (tropical) algebraic geometry
Abstract: I will show how the partition function in statistical mechanics can be interpreted as an algebraic variety. In accordance to earlier literature, the zero-temperature limit is equivalent to taking the tropical limit of the algebraic variety. Previous literature have also generalised the temperature parameter to an n-vector. Here, we show that in the case of n=2, the two components of this generalised quantity are the inverse temperature and inverse temperature times chemical potential, respectively. Other values of n can also be similarly interpreted as various intensive thermodynamic parameters. [Joint work with Mounir Nisse]
Mathematical Physics and Harmonic Analysis Seminar
Time: 4:00PM - 4:50PM
Location: BLOC 302
Speaker: Lim Yen Kheng, Xiamen University Malaysia
Title: Solving physics problems from the perspective of (tropical) algebraic geometry
Abstract: In the first part of the talk, it will be shown how the partition function in statistical mechanics can be interpreted as an algebraic variety. In accordance to earlier literature, the zero-temperature limit is equivalent to taking the tropical limit of the algebraic variety. Previous literature have also generalised the temperature parameter to an n-vector. Here, we show that in the case of n=2, the two components of this generalised quantity are the inverse temperature and inverse temperature times chemical potential, respectively. Other values of n can also be similarly interpreted as various intensive thermodynamic parameters. The second part of the talk concerns null geodesics in four dimensional spacetimes. In particular, we observe that the condition for null circular orbits defines an A-discriminantal variety. A theorem by Rojas and Rusek for A-discriminants leads to the interpretation that there are two branches of null circular orbits for certain classes of spacetimes. A physical consequence of this theorem is that light rings around generic black holes with non-degenerate horizons are unstable. [Joint work with Mounir Nisse]
Free Probability and Operators
Time: 4:00PM - 5:00PM
Location: BLOC 306
Speaker: Ken Dykema, TAMU
Title: On B-valued circular operators
Abstract: We will briefly introduce B-valued circular operators, where B is a *-algebra. We will describe (and perhaps prove) some results about these, in the special case when B is a commutative C*-algebra and describe how they are relevant to the study of DT-operators.
