Let A be a Banach
∗-algebra. A theorem is proved concerning a sufficient condition for a continuous
representation of A on a Hilbert space H to be Naimark-related to a ∗-representation
of A on H. One corollary of this result is that a continuous (topologically) irreducible
representation of A on H is Naimark-related to a ∗-representation of A on H if and
only if some coefficient of the representation is a nonzero positive functional of
A.
One purpose of the paper is to correct in part a previously published result the
proof of which contains a serious gap.