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Leibniz seminorms and best approximation from C*-subalgebras

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Abstract

We show that if B is a C*-subalgebra of a C*-algebra A such that B contains a bounded approximate identity for A, and if L is the pull-back to A of the quotient norm on A/B, then L is strongly Leibniz. In connection with this situation we study certain aspects of best approximation of elements of a unital C*-algebra by elements of a unital C*-subalgebra.

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  1. Department of Mathematics, University of California, Berkeley, CA, 94720-3840, USA

    Marc A. Rieffel

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  1. Marc A. Rieffel
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In celebration of the successful completion by Richard V. Kadison of 85 circumnavigations of the sun

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Rieffel, M.A. Leibniz seminorms and best approximation from C*-subalgebras. Sci. China Math. 54, 2259–2274 (2011). https://doi.org/10.1007/s11425-011-4318-2

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