Hint Resolve lexfg_comp_l.

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