In 1979 T. Ando posed the following question: suppose E and F are two projectionvalued measures defined on an algebra Σ of subsets of Ω, which verifykE(∆) − F(∆)k ≤ 1 − δ, ∆ ∈ Σ,for some δ > 0. Does there exist a unitary ...

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, ...

In this paper we analyze a recent application of perturbation theory by the moment method to a family of two-dimensional anharmonic oscillators. By means of straightforward unitary transformations we show that two of the ...

Consider the Lie group of n×n complex unitary matrices U(n) endowed with the bi-invariant Finsler metric given by the spectral norm, ‖X‖_U=‖U⁎X‖∞=‖X‖∞ for any X tangent to a unitary operator U. Given two points in U(n), ...

Let L(H) be the algebra of bounded operators on a complex separable Hilbert space H.  Let N be a unitary invariant norm  defined on a norm ideal I ⊆ L(H)$. Given two positive invertible operators P, Q ∈ L(H) and k ∈ (-2,2], ...

We study the p-spectrum of a locally symmetric space of constant curvature Γ∖X, in connection with the right regular representation of the full isometry group G of X on (Formula presented.), where τp is the complexified ...