Inside the symmetries of a crystal shape, a postdoctoral researcher has unearthed a counterexample to a basic conjecture about multiplicative inverses. “I’m nearly at the end of the talk, and it’s ...

Let R be an integral domain, K its field of fractions, F a free group. Let I and J be fully invariant (=verbal) ideals of the group algebra KF. We prove that over certain domains the equality IJ ∩ RF ...