Abstract
In this paper, an error in the proof of Theorem 4.9 in Gudder’s paper (Int. J. Theor. Phys. 47(1):268–279, 2008) is pointed out and it is proved that if \(\mathcal {E}\approx \{E_{1},E_{2},\ldots,E_{n}\}\in\mathcal {Q}_{pos}({\mathcal{H}})\setminus \mathcal {Q}_{pro}({\mathcal{H}})\) such that E i ∈ℂI∖{0} and E j ∉ℂI for some i,j in {1,2,…,n}, then \(\mathcal {E}\notin \mbox{Ext}[\mathcal {Q}_{pos}({\mathcal{H}})]\) .
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This subject is supported by the NNSF of China (No. 10571113, 10871224).
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Chen, ZL., Cao, HX. A Note on the Extreme Points of Positive Quantum Operations. Int J Theor Phys 48, 1669–1671 (2009). https://doi.org/10.1007/s10773-009-9939-7
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DOI: https://doi.org/10.1007/s10773-009-9939-7