The different of a branched cover of $3$-manifolds is a square

Abstract: Hecke has shown that the different ideal of a number field is a square in the class group. In joint work with Will Sawin we obtain an analogous result for closed $3$-manifolds saying that the branch divisor of a covering is a square in the first homology group.

number theory

Audience: researchers in the topic

Harvard number theory seminar