Published online by Cambridge University Press: 24 October 2008
Let A be an A*-algebra and let denote its auxiliary norm closure. The multiplier algebras of dual A*-algebras of the first kind have been studed by Tomiuk [12], [13] and Wong[15]. In this paper we study the double multiplier algebra of A*-algebras of the first kind. In particular, we prove that, if A is an A*-algebra of the first kind, then the double multiplier algebra M(A) of A is *-isomorphic and (auxiliary norm) isometric to a subalgebra of M(), extending in the process some results established by Tomiuk[12]. We also consider the embedding of the double multiplier algebra of A in **, when the latter is regarded as an algebra with the Arens product, and, in particular, we show that, for an annihilator A*-algebra, M(A) is *-isomorphic and (auxiliary norm) isometric to **.