New families satisfying the Dynamical Uniform Boundedness Principle over function fields

John R. Doyle, Xander Faber

Published 2022-03-11Version 1

We extend a technique, originally due to the first author and Poonen, for proving cases of the Strong Uniform Boundedness Principle (SUBP) in algebraic dynamics over function fields of positive characteristic. The original method applied to unicritical polynomials for which the characteristic does not divide the degree. We show that many new 1-parameter families of polynomials satisfy the SUBP, including the family of all quadratic polynomials in even characteristic. We also give the first nontrivial example of a family of rational functions that satisfies the SUBP.