Minimal Irreversible Quantum Mechanics: An Axiomatic Formalism
  An axiomatic formalism for a minimal irreversible quantum mechanics is introduced. It is shown that a quantum equilibrium and the decoherence phenomenon are consequences of the axioms and that Lyapunov variables, exponential survival probabilities, and a classisal conditional never-decreasing entropy can be defined. 
Mario Castagnino, Edgard Gunzig