Let U be given.
We will
prove ∃y : set, y ∈ A ∧ y ≠ x ∧ y ∈ U.
An exact proof term for the current goal is (HUprop x HxU).
Apply Hexb to the current goal.
Let b be given.
We prove the intermediate
claim Hbprop:
x ∈ b ∧ b ⊆ U.
We prove the intermediate
claim Hxb:
x ∈ b.
An
exact proof term for the current goal is
(andEL (x ∈ b) (b ⊆ U) Hbprop).
We prove the intermediate
claim HbsubU:
b ⊆ U.
An
exact proof term for the current goal is
(andER (x ∈ b) (b ⊆ U) Hbprop).
Apply HexU0 to the current goal.
Let U0 be given.
We prove the intermediate
claim HU0:
U0 ∈ Tx0.
An
exact proof term for the current goal is
(ReplE Ty (λV0 : set ⇒ rectangle_set U0 V0) b HbRepl).
Apply HexV0 to the current goal.
Let V0 be given.
We prove the intermediate
claim HV0:
V0 ∈ Ty.
rewrite the current goal using Hbeq (from right to left).
An exact proof term for the current goal is Hxb.
We prove the intermediate
claim Hx0U0:
x 0 ∈ U0.
An
exact proof term for the current goal is
(ap0_Sigma U0 (λ_ : set ⇒ V0) x HxRect).
We prove the intermediate
claim Hx1V0:
x 1 ∈ V0.
An
exact proof term for the current goal is
(ap1_Sigma U0 (λ_ : set ⇒ V0) x HxRect).
We prove the intermediate
claim Hx0eq:
x 0 = a 0.
We prove the intermediate
claim Hx1eq:
x 1 = 1.
We prove the intermediate
claim Ha0U0:
a 0 ∈ U0.
rewrite the current goal using Hx0eq (from right to left).
An exact proof term for the current goal is Hx0U0.
We prove the intermediate
claim HV0cases:
V0 = Empty ∨ V0 = Y.
An
exact proof term for the current goal is
(UPairE V0 Empty Y HV0).
We prove the intermediate
claim HV0ne:
V0 ≠ Empty.
We prove the intermediate
claim HV0Y:
V0 = Y.
Apply HV0cases to the current goal.
Apply FalseE to the current goal.
An exact proof term for the current goal is (HV0ne HV0E).
An exact proof term for the current goal is HV0Y'.
rewrite the current goal using HV0Y (from right to left).
An exact proof term for the current goal is HxRect.
We prove the intermediate
claim HaEta:
a = (a 0,a 1).
An
exact proof term for the current goal is
(setprod_eta ω Y a HaX).
We prove the intermediate
claim H0Y:
0 ∈ Y.
An
exact proof term for the current goal is
(UPairI1 0 1).
rewrite the current goal using HV0Y (from left to right).
rewrite the current goal using HaEta (from left to right).
rewrite the current goal using Ha10 (from left to right).
We prove the intermediate
claim HaInb:
a ∈ b.
rewrite the current goal using Hbeq (from left to right).
An exact proof term for the current goal is HaInRect.
We prove the intermediate
claim HaU:
a ∈ U.
An exact proof term for the current goal is (HbsubU a HaInb).
We use a to witness the existential quantifier.
Apply andI to the current goal.
Apply andI to the current goal.
An exact proof term for the current goal is HaA.
We prove the intermediate
claim Heq1:
a 1 = x 1.
rewrite the current goal using Heq (from right to left).
Use reflexivity.
We prove the intermediate
claim H01:
0 = 1.
rewrite the current goal using Ha10 (from right to left) at position 1.
rewrite the current goal using Hx1eq (from right to left) at position 2.
An exact proof term for the current goal is Heq1.
An
exact proof term for the current goal is
(neq_0_1 H01).
An exact proof term for the current goal is HaU.