Dynamical Systems Seminar

Becca WinarskiUniversity of Michigan
Polynomials, branched covers, and trees

Friday, November 15, 2019 - 1:30pm
Malott 205

Thurston proved that a post-critically finite branched cover of the plane is either equivalent to a polynomial (that is: conjugate via a mapping class) or it has a topological obstruction. We use topological techniques – adapting tools used to study mapping class groups – to produce an algorithm that determines when a branched cover is equivalent to a polynomial, and if it is, determines which polynomial a topological branched cover is equivalent to. Our approach gives a new, topological solution to Hubbard's twisted rabbit problem, as well as generalizations of this problem. This is joint work with Jim Belk, Justin Lanier, and Dan Margalit.