Operator Formulation of Classical Mechanics and the Problem of   Measurement
  The basic concepts of classical mechanics are given in the operator form. The dynamical equation for a hybrid system, consisting of quantum and classical subsystems, is introduced and analyzed in the case of an ideal nonselective measurement. The nondeterministic evolution is found to be the consequence of the superposition of two different deterministic evolutions. 
S. Prvanovic and Z. Maric (Institute of Physics, Belgrade, Serbia)