Goal:
  
  __x2 : Z
  __x1 : Z
  __wit := [] : list ZMicromega.ZArithProof
  __varmap := VarMap.Branch (VarMap.Elt __x2) __x1 VarMap.Empty : VarMap.t Z
  __ff := Tauto.IFF
            (Tauto.A Tauto.isProp
               {|
                 RingMicromega.Flhs := EnvRing.PEX 1;
                 RingMicromega.Fop := RingMicromega.OpLe;
                 RingMicromega.Frhs := EnvRing.PEX 2
               |} tt)
            (Tauto.A Tauto.isProp
               {|
                 RingMicromega.Flhs := EnvRing.PEopp (EnvRing.PEX 2);
                 RingMicromega.Fop := RingMicromega.OpLe;
                 RingMicromega.Frhs := EnvRing.PEopp (EnvRing.PEX 1)
               |} tt) : Tauto.BFormula (RingMicromega.Formula Z) Tauto.isProp
  ============================
   (__x1 <= __x2 <-> - __x2 <= - __x1)


DEBUG:Going to execute:
exact
(ZMicromega.ZTautoChecker_sound __ff __wit
   (eq_refl <: ZMicromega.ZTautoChecker __ff __wit = true)
   (VarMap.find 0 __varmap))