DEFINITION subst_sort()
TYPE =
∀v:T.∀d:nat.∀k:nat.(eq T (subst d v (TSort k)) (TSort k))
BODY =
assume : T
assume : nat
assume k: nat
by (refl_equal . .)
we proved eq T (TSort k) (TSort k)
that is equivalent to eq T (subst __2 __3 (TSort k)) (TSort k)
we proved T→nat→∀k:nat.(eq T (subst __2 __3 (TSort k)) (TSort k))