Browsing Waterloo Research by Author "Yahaghi, B.R."

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Ranges of vector states on irreducible operator semigroups

Marcoux, L.W.; Omladič, M.; Popov, A.I.; Radjavi, H.; Yahaghi, B. (Springer, 2016)

Let 𝜑 be a linear functional of rank one acting on an irreducible semigroup S of operators on a finite- or infinite-dimensional Hilbert space. It is a well-known and simple fact that the range of 𝜑 cannot be a singleton. ...
Reducibility of operator semigroups and values of vector states

Marcoux, L.W.; Radjavi, H.; Yahaghi, B.R. (Springer, 2017-08-01)

Let S be a multiplicative semigroup of bounded linear operators on a complex Hilbert space H, and let Ω be the range of a vector state on S so that Ω = {⟨Sξ, ξ⟩ : S ∈ S} for some fixed unit vector ξ ∈ H. We study the ...