fact: Fixpoint free_in_aexp (x: ident) (a: aexp) : Prop := match a with | CONST n => False | VAR y => y = x | PLUS a1 a2 | MINUS a1 a2 => free_in_aexp x a1 \/ free_in_aexp x a2 end.
imports: Coq(Arith ZArith Psatz Bool String List Program.Equality) CDF(Sequences Simulation)