destruct case_ELet; intros; simpl in *.
eapply nd_comp; [ idtac | eapply nd_rule; eapply RLet ].
eapply nd_comp; [ apply nd_llecnac | idtac ].
- apply nd_prod; [ idtac | apply pf_let].
- clear pf_let.
- eapply nd_comp; [ apply pf_body | idtac ].
- clear pf_body.
+ apply nd_prod.
+ apply pf_let.
+ clear pf_let.
+ eapply nd_comp; [ apply pf_body | idtac ].
+ clear pf_body.
fold (@mapOptionTree VV).
fold (mapOptionTree ξ).
set (update_ξ ξ v ((lev,tv)::nil)) as ξ'.