Linear transformations which preserve hermitian and positive semidefinite operators
John de Pillis · Pacific Journal of Mathematics · 1967
JOHN de PILLISLet Si and 33 represent the full algebras of linear operators on the finite-dimensional unitary spaces έ%f and J3Γ", respectively.The symbol =5^(51, 23) will denote the complex space of all linear maps from % to 33.This paper concerns itself with the study of the following two cones in iϊ^(2ϊ, 33):(i) the cone <gf of all Te £f(& 9 53) which send hermitian operators in 51 to hermitian operators in 33, and(ii) the subcone