Goal:
  
  G : t
  HI : invariants G
  HG : acyclic_no_loop G
  b : bool
  H0 : is_true b
  H : is_true (~~ true)
  ============================
   False


DEBUG:Going to execute:
match goal with
           | H:_ /\ _ |- _ => exact H || (destruct_hyp H; use_hyps)
           | H:(_ * _)%nat |- _ => exact H || (destruct_hyp H; use_hyps)
           | H:_ |- _ => solve [ inversion H ]
           | _ => idtac
           end