“…This interpretation of Theorem 1.3 was kindly brought to my attention by Wolfgang Arendt. - A similar approach as in the proof above, using Perron–Frobenius theory and Gelfand's theorem to show that a given semigroup generator equals 0, was used in [9, Section 2] to give a new proof of a classical result of Sherman about lattice ordered ‐algebras.The same comments as at the end of [9, Section 2] also apply to the proof above; in particular:
- (e)The Perron–Frobenius type theorem from [17, Corollary C‐III‐2.13] that we used in the proof relies on quite heavy machinery. However, we only use the result for semigroups with bounded generators, for which it is much simpler to prove — see, for instance, [9, Proposition 2.2].
- (f)Our proof also uses Gelfand's theorem for ‐semigroups which is not quite trivial. But again, we apply this theorem only for semigroups with bounded generator — and for these, it can be derived from the single operator version of Gelfand's theorem, which is a bit simpler (see, for instance, [1, Theorem 1.1]).
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