Notation lexfg := (e_lexfg _) (only parsing).

Theorem lexfg_cons_t : forall (a a' : terms) (s : sub_explicits), e_lexfg _ (e_P1 wt) (e_P2 wt) a a' -> e_lexfg _ (e_P1 ws) (e_P2 ws) (cons a s) (cons a' s).