A result on positive matrices and applications to Hankel operators
Marcus Carlsson · Operators and Matrices · 2011
Let S denote the shift operator on l 2 (N) and set e 0 = (1,0,0,...) . A special case of the main result says that if W is a self-adjoint operator on l 2 (N) such that W (e 0 ) = 0 and S * W S W , then W 0 . We apply this result to AAK-type theorems on generalized Hankel operators, providing new insights related to previous work by S.