Volume 30 • Number 2 • 2007   • Automatic Continuity of 3-Homomorphisms on Banach Algebras Janko Bracic and Mohammad Sal Moslehian Abstract. A linear map φ :A → B between (Banach) algebras is called 3-homomorphism if φ(abc)= φ(a) φ(b) φ(c) for each a, b, c ∈ A. We investigate 3-homomorphisms on Banach algebras with bounded approximate identities and establish in two ways (for unital and non-unital cases) that every involution preserving homomorphism between C*-algebras is norm decreasing. 2000 Mathematics Subject Classification: Primary 47B48, Secondary 46L05, 16Wxx Full text: PDF