Hint Resolve lexfg_cons_s.

(* Specifications: *)
Theorem lexfg_comp_l :
forall s s' t : sub_explicits,
e_lexfg _ (e_P1 ws) (e_P2 ws) s s' ->
e_lexfg _ (e_P1 ws) (e_P2 ws) (comp s t) (comp s' t).