\forall (a1: A).(\forall (a2: A).(llt a1 (AHead a1 a2)))
\def
\lambda (a1: A).(\lambda (a2: A).(le_n_S (lweight a1) (plus (lweight a1)
(lweight a2)) (le_plus_l (lweight a1) (lweight a2)))).
\forall (a1: A).(\forall (a2: A).(llt a1 (AHead a1 a2)))
\def
\lambda (a1: A).(\lambda (a2: A).(le_n_S (lweight a1) (plus (lweight a1)
(lweight a2)) (le_plus_l (lweight a1) (lweight a2)))).