Let X, Y, d, fn, N, eps1 and eps2 be given.
Let x be given.
We will
prove x ∈ A_N_eps X Y d fn N eps2.
rewrite the current goal using HdefA2 (from left to right).
We prove the intermediate
claim HxX:
x ∈ X.
Let n be given.
Let m be given.
An exact proof term for the current goal is (HxProp n HnO HNn m HmO HNm).
∎