Rings of Hilbert modular forms
Rings of Integers and Trace Forms for Tame Extensions of Odd Degree.
Rings of integers of type .
Ring-theoretic properties of Iwasawa algebras: a survey.
Roots of unity in definite quaternion orders
A commutative order in a quaternion algebra is called selective if it embeds into some, but not all, of the maximal orders in the algebra. It is known that a given quadratic order over a number field can be selective in at most one indefinite quaternion algebra. Here we prove that the order generated by a cubic root of unity is selective for any definite quaternion algebra over the rationals with type number 3 or larger. The proof extends to a few other closely related orders.
Rotations in the space of Split octonions.
Rotations sur les groupes, nombres algébriques, et substitutions