Construction of Integrals of Higher-Order Mappings
  We find that certain higher-order mappings arise as reductions of the integrable discrete A-type KP (AKP) and B-type KP (BKP) equations. We find conservation laws for the AKP and BKP equations, then we use these conservation laws to derive integrals of the associated reduced maps. 
Ken-ichi Maruno and G. R. W. Quispel