If K is a field whose characteristic is not 2, a quaternion algebra over K is a an algebra over the basis [1,i,j,ij] where i and j satisfy the relations: i2=a j2 =b ij=-ji for a,b in K*. It turns out that for general ...
The thesis deals with reduction in linear groups and orthogonal groups. Any matrix y in the set of all n by n symmetric positive definite matrices, can be written as the transpose of an invertible matrix g multiplied by ...