Chair of the colloquium: Prof. Mahan Mj (TIFR Mumbai)
Release of the lecture video on YouTube: March 30, 2022 at 18:00 hrs Indian time
Interactive session on Zoom: April 20, 2022 at 18:00 hrs Indian time
Title: Finite quotients of 3-manifold groups
Abstract: For any finite group G, it is easy to see there exists a compact, oriented 3 dimensional manifold M with G as a quotient of the fundamental group of M. However, we can ask more detailed questions about the possible finite quotients of 3-manifold groups, e.g. for G and H finite groups, does there exist a 3-manifold group with G as a quotient but not H as a quotient? We answer all such questions. To prove non-existence, we prove new parity properties of the fundamental groups of 3-manifolds. To prove existence of 3-manifolds with certain finite quotients but not others, we use a probabilistic method, by first proving a formula for the distribution of the fundamental group of a random 3-manifold, in the sense of Dunfield-Thurston. This is joint work with Will Sawin.