Complete description of derivations on -compact operators for type I von Neumann algebras

Given a type I von Neumann algebra M with a faithful normal semi-finite trace �, let S0(M,�) be the algebra of all �-compact operators affiliated with M. We give a complete description of all derivations on the algebra S0(M,�). In particular, we prove that if M is of type I∞ then every derivation on S0(M,�) is spatial.