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# Unbounded derivations and *-automorphisms groups of Banach quasi *-algebras

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## Abstract

This paper is devoted to the study of unbounded derivations on Banach quasi *-algebras with a particular emphasis to the case when they are infinitesimal generators of one parameter automorphisms groups. Both of them, derivations and automorphisms are considered in a weak sense; i.e., with the use of a certain families of bounded sesquilinear forms. Conditions for a weak *-derivation to be the generator of a *-automorphisms group are given.

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Università di Palermo, I-90123 Palermo, Italy E-mail address: mariastella.adamo@community.unipa.it; msadamo@unict.it Camillo Trapani, Dipartimento di Matematica e Informatica, Università di Palermo, I-90123 Palermo