On EPr and normal Epr matrices
Irving Jack Katz, Martin H. Pearl · Journal of Research of the National Bureau of Standards Section B Mathematics and Mathematical Physics · 1966
1) EPr matrices A (that is, matrices A tor which A and A * hav e the same null space) are investi gated. It is shown that if A is a complex EPr, matrix and B a com pl ex EPr2 matrix, and AB = BA, then AB is EPr. Other theorems about products of EPr matrices are es tablished.