Let X, Tx and U be given.
Let P be given.
We use P to witness the existential quantifier.
We prove the intermediate
claim HD:
∀f : set, f ∈ P → ∃u : set, u ∈ U ∧ support_of X Tx f ⊆ u.
Apply andI to the current goal.
Apply andI to the current goal.
Apply andI to the current goal.
Apply andI to the current goal.
An exact proof term for the current goal is HA.
An exact proof term for the current goal is HB.
An exact proof term for the current goal is HC.
An exact proof term for the current goal is HD.
An exact proof term for the current goal is HE.
∎