Numerical Range in C*-Algebras
Let A be a C*-algebra with unit 1 and let S be the state space of A, i.e., S = {ϕ ∈ A∗ : ϕ > 0, ϕ(1) = 1}. For each a ∈ A, the C*-algebra numerical range is defined by V (a) := {ϕ(a) : ϕ ∈ S}. We prove that if V (a) is a disc with center at the origin, then ka+a ∗ k = ka − a ∗ k...
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| Format: | Article |
| Language: | English |
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Islamic Azad University
2012-06-01
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| Series: | Journal of Mathematical Extension |
| Online Access: | http://ijmex.com/index.php/ijmex/article/view/167/89 |