- eapply nd_comp; [ idtac | eapply nd_rule; apply RJoin ].
- eapply nd_comp; [ apply nd_llecnac | idtac ].
- apply nd_prod; auto.
- Defined.
+ eapply nd_comp; [ idtac | eapply RCut' ].
+ eapply nd_comp; [ apply nd_llecnac | idtac ].
+ apply nd_prod.
+ apply IHX1.
+ eapply nd_comp; [ idtac | eapply nd_rule; eapply RLeft ].
+ apply IHX2.
+ Defined.