M. Anoussis et Eg. Katsoulis, COMPACT-OPERATORS AND THE GEOMETRIC STRUCTURE OF C-ASTERISK-ALGEBRAS, Proceedings of the American Mathematical Society, 124(7), 1996, pp. 2115-2122
Given a C-algebra A and an element A is an element of A, we give nece
ssary and sufficient geometric conditions equivalent to the existence
of a representation (phi, H) of A so that phi(A) is a compact or a fin
ite-rank operator. The implications criteria on the geometric structur
e of C-algebras are also discussed.