Let x be given.
Assume HxCap.
Assume HxU HxV.
We prove the intermediate
claim Hexb1:
∃b1 ∈ B, x ∈ b1 ∧ b1 ⊆ U.
An exact proof term for the current goal is (HUprop x HxU).
We prove the intermediate
claim Hexb2:
∃b2 ∈ B, x ∈ b2 ∧ b2 ⊆ V.
An exact proof term for the current goal is (HVprop x HxV).
Apply Hexb1 to the current goal.
Let b1 be given.
Assume Hbpair1.
We prove the intermediate
claim Hb1:
b1 ∈ B.
An
exact proof term for the current goal is
(andEL (b1 ∈ B) (x ∈ b1 ∧ b1 ⊆ U) Hbpair1).
We prove the intermediate
claim Hb1prop:
x ∈ b1 ∧ b1 ⊆ U.
An
exact proof term for the current goal is
(andER (b1 ∈ B) (x ∈ b1 ∧ b1 ⊆ U) Hbpair1).
We prove the intermediate
claim Hb1x:
x ∈ b1.
An
exact proof term for the current goal is
(andEL (x ∈ b1) (b1 ⊆ U) Hb1prop).
We prove the intermediate
claim Hb1Sub:
b1 ⊆ U.
An
exact proof term for the current goal is
(andER (x ∈ b1) (b1 ⊆ U) Hb1prop).
Apply Hexb2 to the current goal.
Let b2 be given.
Assume Hbpair2.
We prove the intermediate
claim Hb2:
b2 ∈ B.
An
exact proof term for the current goal is
(andEL (b2 ∈ B) (x ∈ b2 ∧ b2 ⊆ V) Hbpair2).
We prove the intermediate
claim Hb2prop:
x ∈ b2 ∧ b2 ⊆ V.
An
exact proof term for the current goal is
(andER (b2 ∈ B) (x ∈ b2 ∧ b2 ⊆ V) Hbpair2).
We prove the intermediate
claim Hb2x:
x ∈ b2.
An
exact proof term for the current goal is
(andEL (x ∈ b2) (b2 ⊆ V) Hb2prop).
We prove the intermediate
claim Hb2Sub:
b2 ⊆ V.
An
exact proof term for the current goal is
(andER (x ∈ b2) (b2 ⊆ V) Hb2prop).
We prove the intermediate
claim Hexb3:
∃b3 ∈ B, x ∈ b3 ∧ b3 ⊆ b1 ∩ b2.
An exact proof term for the current goal is (HBint b1 Hb1 b2 Hb2 x Hb1x Hb2x).
Apply Hexb3 to the current goal.
Let b3 be given.
Assume Hbpair3.
We prove the intermediate
claim Hb3:
b3 ∈ B.
An
exact proof term for the current goal is
(andEL (b3 ∈ B) (x ∈ b3 ∧ b3 ⊆ b1 ∩ b2) Hbpair3).
We prove the intermediate
claim Hb3prop:
x ∈ b3 ∧ b3 ⊆ b1 ∩ b2.
An
exact proof term for the current goal is
(andER (b3 ∈ B) (x ∈ b3 ∧ b3 ⊆ b1 ∩ b2) Hbpair3).
We prove the intermediate
claim HxB3:
x ∈ b3.
An
exact proof term for the current goal is
(andEL (x ∈ b3) (b3 ⊆ b1 ∩ b2) Hb3prop).
We prove the intermediate
claim Hb3Sub:
b3 ⊆ b1 ∩ b2.
An
exact proof term for the current goal is
(andER (x ∈ b3) (b3 ⊆ b1 ∩ b2) Hb3prop).
We use b3 to witness the existential quantifier.
Apply andI to the current goal.
An exact proof term for the current goal is Hb3.
Apply andI to the current goal.
An exact proof term for the current goal is HxB3.
Let y be given.
Assume Hyb3.
We prove the intermediate
claim Hy_in_b1b2:
y ∈ b1 ∩ b2.
An exact proof term for the current goal is (Hb3Sub y Hyb3).
Assume Hyb1 Hyb2.
Apply binintersectI U V y (Hb1Sub y Hyb1) (Hb2Sub y Hyb2) to the current goal.