Definition eval_Psatz  : list (NFormula Z) -> ZWitness ->  option (NFormula Z) :=
  eval_Psatz 0 1 Z.add Z.mul Zeq_bool Z.leb.Definition valid_cut_sign (op:Op1) :=
  match op with
    | Equal => true
    | NonStrict => true
    | _         => false
  end.Definition bound_var (v : positive) : Formula Z :=
  Build_Formula (PEX v) OpGe (PEc 0).Definition mk_eq_pos (x : positive) (y:positive) (t : positive) : Formula Z :=
  Build_Formula (PEX x) OpEq (PEsub (PEX y) (PEX t)).Fixpoint vars (jmp : positive) (p : Pol Z) : list positive :=
  match p with
  | Pc c => nil
  | Pinj j p => vars (Pos.add j jmp) p
  | PX p j q => jmp::(vars jmp p)++vars (Pos.succ jmp) q
  end.Fixpoint max_var (jmp : positive) (p : Pol Z) : positive :=
  match p with
  | Pc _ => jmp
  | Pinj j p => max_var (Pos.add j jmp) p
  | PX p j q => Pos.max (max_var jmp p) (max_var (Pos.succ jmp) q)
  end.

Lemma pos_le_add : forall y x, (x <= y + x)%positive.