New York Journal of Mathematics
Volume 26 (2020), 790-798


Sriram Balasubramanian

A note on decomposable maps on operator systems

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Published: July 26, 2020.
Keywords: Positive maps, completely positive (cp) maps, co-completely positive (co-cp) maps, decomposable maps.
Subject: 46L05, 15B48 (Primary), 47B65, 47L07 (Secondary).

This article contains a characterization of operator systems S with the property that every positive map φ: S → Mn is decomposable, as well as an alternate and a more direct proof of a characterization of decomposable maps due to Erling Størmer.


Research supported by the grant MTR/2018/000113 from the Department of Science and Technology, India. The author would like to thank Prof. Scott McCullough for many helpful suggestions and Prof. Erling Størmer for useful comments during the initial stages of this work.

Author information

Sriram Balasubramanian:
Department of Mathematics
IIT Madras
Chennai - 600036, India