Inductive plus: state -> state -> Prop :=
  | plus_left: forall s1 s2 s3,
      CCstep s1 s2 -> star s2 s3 -> plus s1 s3.Inductive plus: state -> state -> Prop :=
  | plus_left: forall s1 s2 s3,
      CCstep s1 s2 -> star s2 s3 -> plus s1 s3.

Lemma exec_skips': forall f s k' s0 k0' ve te m, strip_skip' (CC.Kseq s k') = CC.Kseq s0 k0' -> star (CC.State f s k' ve te m) (CC.State f s0 k0' ve te m).