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    • Keywords


      Smooth subalgebra of a $C^∗$-algebra; spectral invariance; closure under functional calculus; Arens–Michael decomposition of a Frechet algebra; Banach $(D^∗_p)$-algebra; Frechet $(D^∗_\infty)$-algebra.

    • Abstract


      The paper contributes to understanding the differential structure in a $C^∗$-algebra. Refining the Banach $(D^∗_p)$-algebras investigated by Kissin and Shulman as noncommutative analogues of the algebra $C^p[a,b]$ of 𝑝-times continuously differentiable functions, we investigate a Frechet $(D^∗\infty)$-subalgebra $\mathcal{B}$ of a $C^∗$-algebra as a noncommutative analogue of the algebra $C^\infty[a,b]$ of smooth functions. Regularity properties like spectral invariance, closure under functional calculi and domain invariance of homomorphisms are derived expressing $\mathcal{B}$ as an inverse limit over 𝑛 of Banach $(D^∗_n)$-algebras. Several examples of such smooth algebras are exhibited.

    • Author Affiliations


      Subhash J Bhatt1 Dinesh J Karia1 Meetal M Shah1

      1. Department of Mathematics, Sardar Patel University, Vallabh Vidyanagar, Gujarat 388 120, India
    • Dates

  • Proceedings – Mathematical Sciences | News

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