Combinatorics seminar
Speaker: Jagdeep Singh, Mississippi State University
Host: Niranjan Balachandran
Title: From Cographs to Comatroids: Forbidden Structures and Apex Classes
Time, day and date: 10:00:00 AM - 11:00:00 AM, Wednesday, March 25
Venue: Online (https://meet.google.com/pcb-jarm-pvq)
Abstract: Complement reducible graphs, or cographs, form one of the most well-understood hereditary classes of graphs: they admit linear-time recognition, possess multiple elegant characterizations, and have a simple forbidden subgraph description (no induced path of length three). In this talk, I will describe two natural generalizations of cographs: 2-cographs and sesquicographs. I will then present results showing that apexing (adding a single vertex or edge) preserves the finiteness of forbidden induced subgraphs, along with explicit bounds on their size. Finally, I will extend this framework from graphs to binary matroids, introducing comatroids as the natural matroid analogue of cographs. Analogous extension results hold in this setting. This work includes joint work with James Oxley, Thomas Zaslavsky and Vaidy Sivaraman.

Link for the talk: https://meet.google.com/pcb-jarm-pvq

Talk
Speaker: Chandan Bhaumik, IIT Bombay
Host: Manoj Kumar Keshari
Title: The Steinberg Group and the K_2 Functor
Time, day and date: 11:30:00 AM – 12:30:00 PM, Wednesday, March 25
Venue: Ramanujan Hall
Abstract: This series of talks focuses on the computation of the K_2 group for the ring of integers. In the first talk, we will cover the definition of the Steinberg group and the K_2 functor, along with some fundamental properties.

PDE Seminar
Speaker: Saroj Si, IIT Roorkee
Host: Harsha Hutridurga
Title: On the well-posedness of the growth–coagulation models with singular coagulation kernels
Time, day and date: 2:30:00 PM – 3:30:00 PM, Wednesday, March 25
Venue: Ramanujan Hall
Abstract: Attached (https://drive.google.com/drive/folders/1SlhC3HhNTTBJxX2b1Sbvkbck7EKwLUyJ)

Mathematics Colloquium
Speaker: Keshav Aggarwal, IIT Bombay
Title: Cancellations in sums of arithmetic functions
Time, day and date: 4:00:00 PM - 5:00:00 PM, Wednesday, March 25
Venue: Ramanujan Hall
Abstract: Many important number theoretic problems relate to the rate of growth of sums of arithmetically interesting functions. Some of these problems include bounding the least quadratic non-residue, Quantum Unique Ergocidity conjecture of Rudnick and Sarnak, bounding moments of L-functions, simultaneous non-vanishing of L functions and the subconvexity bound problem. We will give an overview of how various such problems relate to obtaining cancellations in certain sums, and the recent methods developed in this direction.