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Closed range of Φ(1) for C*-extreme points of CCP(A,B(H))

Ascertain whether, for any C*-extreme point Φ of the C*-convex set CCP(A,B(H)) of contractive completely positive maps, the operator Φ(1) necessarily has closed range; equivalently, determine whether the assumption “range(Φ(1)) is closed” in Lemma 4.10 holds automatically for such Φ.

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Background

Lemma 4.10 proves that if Φ ∈ CCP C*-ext(A,B(H)) and range(Φ(1)) is closed, then Φ(1) is a projection. The authors note uncertainty about whether the closed-range condition is automatic for C*-extreme points, which would immediately imply the projection property and facilitate structural results.

References

In the above lemma, we are uncertain whether the assumption that range (Φ(1)) is closed follows automatically if Φ is a C ∗-extreme point.

$C^*$-extreme contractive completely positive maps (2412.05008 - R et al., 6 Dec 2024) in After Lemma 4.10, Section 4.2