Seferoglu, H.2025-05-102025-05-1020070025-584X10.1002/mana.2004105252-s2.0-34250312855https://doi.org/10.1002/mana.200410525https://hdl.handle.net/20.500.14720/6715Let T = {T (t)}(t is an element of R) be a Co-group on a Banach space X with generator A. Under what conditions the assumption sigma (A) = {0} implies that A = 0 ? This is called "A = 0" problem. In this paper we present some results related to this problem. (c) 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.eninfo:eu-repo/semantics/closedAccessRepresentation GroupSpectrumBanach AlgebraGroup AlgebraArticle2808Q2Q2924931WOS:000247269500010