Remarks on the Generalized Chaplygin Gas
  We have developed an action formulation for the Generalized Chaplygin Gas   (GCG). The most general form for the nonrelativistic GCG action is derived consistent with the equation of state. We have also discussed a relativistic formulation for GCG by providing a detailed analysis of the Poincare algebra. 
Rabin Banerjee, Subir Ghosh and Shailesh Kulkarni