Sul teorema di Gelfand-Mazur
In this note we produce a complex algebra without characters and which does not contain a proper extension of the complex number field.
In this note we produce a complex algebra without characters and which does not contain a proper extension of the complex number field.
A lemma of Gelfand-Hille type is proved. It is used to give an improved version of a result of Kalton on sums of idempotents.
We generalize to some classes of ultradifferentiable jets or functions the classical Łojasiewicz Division Theorem and Glaeser Composition Theorem. The proof uses the desingularization results by Hironaka, Bierstone and Milman.
Let A be a Banach *-algebra which is a subalgebra of a Banach algebra B. In this paper, assuming that A is symmetric, various conditions are given which imply that A is inverse closed in B.