Completeness of the system of root vectors of operators in a space with indefinite metric
Hilbert space operators written in the form \(A=H(I+S)\) are considered. Various conditions on H and S sufficient for the system of root vectors of A to be complete are announced. Part of these conditions have to do with compactness and behaviour in an indefinite metric.
completeness of the system of root vectors of a linear pencil
scientific article; zbMATH DE number 4190477