The observables of a dissipative quantum system
  A time-dependent product is introduced between the observables of a dissipative quantum system, that accounts for the effects of dissipation on observables and commutators. In the $t \to \infty$ limit this yields a contracted algebra. The general ideas are corroborated by a few explicit examples. 
Dariusz Chru\'sci\'nski, Paolo Facchi, Giuseppe Marmo and Saverio   Pascazio
quant-ph math-ph math.MP