Title: Symmetries of the set of squarefree integers in a number field
Abstract: Let K be a number field. We answer the following question and several generalizations:
What are the Z-linear maps O_K -> O_K that send every squarefree algebraic integer to a squarefree algebraic integer?
In the talk at 11:15am, Michael Baake will introduce dynamical systems associated to k-free algebraic integers.
Our result can be used to determine when two such dynamical systems are topologically conjugate, and more generally when one is a factor system of another.