Block Conjugacy of Irreducible Toral Automorphisms

We introduce a relation of block conjugacy for irreducible toral automorphism, and prove that block conjugacy is equivalent to weak equivalence of the ideals associated to the automorphisms. We characterize when block conjugate automorphisms are actually conjugate in terms of a group action on invariant and invariantly complemented subtori, and detail the relation of block conjugacy with a Galois group. We also investigate the nature of the relationship between ideals associated to non-block conjugate irreducible automorphisms.