fact: Fixpoint PP_mult (e f:expr) {struct e} : expr := let d := expr_mult e f in match e, f with | expr_plus e1 e2, f => PP_plus (PM_mult f e1) (PP_mult e2 f) | expr_int i, f => PM_mult f e | _, _ => d end.
imports: CoRN.logic.CLogic Coq.Bool.Bool