On the operator equation AXB + CYD = Z
Don Hadwin, Eric Nordgren, Peter Rosenthal · Operators and Matrices · 2007
Suppose two n -tuples of operators A k and B k on a Hilbert space are given, and is the mapping from the set of n -tuples of operators on the Hilbert space into the set of all operators on the space defined by (X 1 , X 2 , . . . ,