Goal:
    x : t  X : lt x x
  ============================
   False


DEBUG:Going to execute:
fun tac H =>
             try intros until H; intro_block H;
              (try simpl in H; DepElim.simplify_equations_in H);
              DepElim.generalize_by_eqs_vars H; CoreTactics.block_goal; 
              tac H; CoreTactics.intros_until_block; DepElim.simpl_dep_elim;
              CoreTactics.unblock_goal