- eapply nd_comp; [ eapply nd_rule; eapply RArrange; eapply ACanL | idtac ].
- eapply nd_comp; [ idtac | eapply nd_rule; eapply RArrange; eapply AExch (* okay *)].
+ eapply nd_comp.
+ eapply nd_rule.
+ eapply RArrange.
+ eapply ALeft.
+ eapply ARight.
+ unfold x1.
+ rewrite drop_to_nothing.
+ apply arrangeCancelEmptyTree with (q:=(mapTree (fun _ : ??(HaskType Γ ★) => tt) Σ₁₂)).
+ admit. (* OK *)
+ eapply nd_comp; [ eapply nd_rule; eapply RArrange; eapply ALeft; eapply ACanL | idtac ].
+ set (mapOptionTree flatten_type Σ₁₂) as a.
+ set (mapOptionTree (flatten_type ○ unlev) (take_lev (ec :: lev) Σ₁)) as b.
+ set (mapOptionTree flatten_leveled_type (drop_lev (ec :: lev) Σ₂)) as c.
+ set (mapOptionTree (flatten_type ○ unlev) (take_lev (ec :: lev) Σ₂)) as d.
+ set (mapOptionTree flatten_leveled_type (drop_lev (ec :: lev) Σ)) as e.
+ set (mapOptionTree (flatten_type ○ unlev) (take_lev (ec :: lev) Σ)) as f.
+ eapply nd_comp; [ idtac | eapply nd_rule; eapply RCut ].
+ eapply nd_comp; [ apply nd_llecnac | idtac ].
+ apply nd_prod.
+ simpl.
+ eapply secondify.
+ apply ga_first.
+ eapply nd_comp; [ idtac | eapply nd_rule; eapply RArrange; eapply ALeft; eapply AExch ].
+ eapply nd_comp; [ idtac | eapply nd_rule; eapply RArrange; eapply AuAssoc ].
+ simpl.