Range of a contractive strongly positive projection in a $C^*$-algebra
Volume 140 / 2015
Colloquium Mathematicum 140 (2015), 87-89
MSC: Primary 46L05; Secondary 46L55.
DOI: 10.4064/cm140-1-7
Abstract
We generalize a result of Choi and Effros on the range of a contractive completely positive projection in a $C^*$-algebra to the case when this projection is only strongly positive using, moreover, an elementary argument instead of a $2\times 2$-matrix technique.
