University of Sydney Algebra Seminar

John Voight

Friday 7 March, 12-1pm, in Carslaw 175

Orders with cancellation

We consider orders in (possibly noncommutative) semisimple algebras over the rationals whose associated category of projective modules has a cancellation property. Examples include the group ring of a finite group over the integers. We give a complete characterization in the very interesting case when the algebra is a definite quaternion algebra over a totally real field. This is joint work with Daniel Smertnig.