Square roots of elements with an unbounded spectrum. (English) Zbl 0603.46054

The author considers projective limits of Banach algebras. The spectrum of an element of this kind of algebra is not necessarily bounded. The paper shows the existence of a square root of elements with positive spectrum and studies the particular case of involution algebras.
Reviewer: H.Hogbe-Nlend


46H05 General theory of topological algebras
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