Cagdas Evren Gerede Oscar H. Ibarra Bala Ravikumar Jianwen Su Minimum-cost delegation in service composition. 417-431 2008 409 Theor. Comput. Sci. 3 http://dx.doi.org/10.1016/j.tcs.2008.08.040 db/journals/tcs/tcs409.html#GeredeIRS08