Videos

Geometric monodromy of families of framed Riemann surfaces

Presenter
March 25, 2022
Abstract
A family of Riemann surfaces gives rise to a geometric monodromy group valued in the mapping class group of the fiber. In a surprising diversity of examples in algebraic geometry (e.g. linear systems on algebraic surfaces, Milnor fibers of an isolated plane curve singularity, strata of abelian differentials), the fibers come endowed with a canonical framing (or some close cousin known as an "r-spin structure"). This forces the monodromy group to stabilize this framing up to isotopy, and one would like to know if this gives a complete description - is the monodromy group *equal* to the associated “framed mapping class group”? I will give an account of this story, with the ultimate aim of explaining how the methods of geometric group theory can be used to give a positive answer in each of the situations mentioned above, and the consequences this has for the study of vanishing cycles and of injectivity properties of monodromy groups. This incorporates joint work with Calderon and with Portilla Cuadrado.