The on-line scheduling of systems of imprecise-computation tasks is in
vestigated. The system objective is to maximize the value obtained. A
formal model is defined. Under certain reasonable assumptions-formaliz
ed here as the weak feasible mandatory constraint-a competitive on-lin
e scheduling algorithm is presented for the commonly studied uniform-d
ensity task systems. It is proven, however, that an on-line algorithm
may, in general, perform arbitrarily poorly as compared to a clairvoya
nt scheduler.