Loading [MathJax]/extensions/MathZoom.js
In this paper, first we introduce a new notion of commuting condition that between the shape operator and the structure tensors and for real hypersurfaces in . Suprisingly, real hypersurfaces of type , that is, a tube over a totally geodesic in complex two plane Grassmannians satisfy this commuting condition. Next we consider a complete classification of Hopf hypersurfaces in satisfying the commuting condition. Finally we get a characterization of Type in terms of such commuting...
A representation field for a non-maximal order in a central simple algebra is a subfield of the spinor class field of maximal orders which determines the set of spinor genera of maximal orders containing a copy of . Not every non-maximal order has a representation field. In this work we prove that every commutative order has a representation field and give a formula for it. The main result is proved for central simple algebras over arbitrary global fields.
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.
Currently displaying 1 –
7 of
7