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Characterization of unitary operators by elementary operators and unitarily invariant norms
(Element, 2012-01)
In this work we characterize unitary operators via inequalities of elementary operators with unitarily invariant norms.
Unitary subgroups and orbits of compact self-adjoint operators
(Polish Academy of Sciences. Institute of Mathematics, 2017-05)
Let H be a separable Hilbert space, and let D(B(H) ah) be the antiHermitian bounded diagonal operators in some fixed orthonormal basis and K(H) the compact operators. We study the group of unitary operators Uk,d = {u ∈ ...
Spectral properties for perturbations of unitary operators
(ACADEMIC PRESS INC ELSEVIER SCIENCE, 2011)
Consider a unitary operator U-0 acting on a complex separable Hilbert space H. In this paper we study spectral properties for perturbations of U-0 of the type,
Unitary operators with decomposable corners
(Banach Mathematical Research Group, 2021-01)
We study pairs (U, L) , where U is a unitary operator in H and L⊂ H is a closed subspace, such that PL0U|L0:L0→L0has a singular value decomposition. Abstract characterizations of this condition are given, as well as relations ...
Casimir operators of complementary unitary groups
(1974-01-01)
A relationship between all the generalized Casimir operators of complementary unitary groups is derived, both in the fermion and boson realizations of the corresponding Lie algebras. It is shown that the number of independent ...
Geodesic neighborhoods in unitary orbits of self-adjoint operators of K + C
(Elsevier Science, 2021-08)
In the present paper, we study the unitary orbit of a compact Hermitian diagonal operator with spectral multiplicity one under the action of the unitary group U(K+C) of the unitization of the compact operators K(H) + C, ...
UNITARY EXTENSIONS OF TWO-PARAMETER LOCAL SEMIGROUPS OF ISOMETRIC OPERATORS AND THE KREIN EXTENSION THEOREM
(Integral equations and operator theory., 2013)
Unitary subgroups and orbits of compact self-adjoint operators
(Instytut Matematyczny, 2017)