∀A.∀a,x.∀p:\ 5a href="cic:/matita/basics/logic/eq.ind(1,0,2)"\ 6eq\ 5/a\ 6 ? x a.∀P: ∀x:A. \ 5a href="cic:/matita/basics/logic/eq.ind(1,0,2)"\ 6eq\ 5/a\ 6 ? x a → Type[3]. P a (\ 5a href="cic:/matita/basics/logic/eq.con(0,1,2)"\ 6refl\ 5/a\ 6 A a) → P x p.
#A #a #x #p (cases p) // qed.
∀A.∀a,x.∀p:\ 5a href="cic:/matita/basics/logic/eq.ind(1,0,2)"\ 6eq\ 5/a\ 6 ? x a.∀P: ∀x:A. \ 5a href="cic:/matita/basics/logic/eq.ind(1,0,2)"\ 6eq\ 5/a\ 6 ? x a → Type[3]. P a (\ 5a href="cic:/matita/basics/logic/eq.con(0,1,2)"\ 6refl\ 5/a\ 6 A a) → P x p.
#A #a #x #p (cases p) // qed.