| Step | Hyp | Ref
 | Expression | 
| 1 |   | df-op 4567 | 
. 2
⊢ 〈A, B〉 = ({x ∣ ∃y ∈ A x =  Phi y} ∪ {x
∣ ∃y ∈ B x = ( Phi y ∪ {0c})}) | 
| 2 |   | vex 2863 | 
. . . . . 6
⊢ x ∈
V | 
| 3 | 2 | elimak 4260 | 
. . . . 5
⊢ (x ∈
(Imagek((Imagek(( Ins3k ∼ (( Ins3k Sk ∩ Ins2k Sk ) “k ℘1℘11c) ∖ (( Ins2k Ins2k Sk ⊕ ( Ins2k Ins3k Sk ∪ Ins3k SIk SIk Sk )) “k ℘1℘1℘1℘11c))
“k ℘1℘11c) ∩ ( Nn ×k V)) ∪ (
Ik ∩ ( ∼ Nn
×k V))) “k A) ↔ ∃y ∈ A
⟪y, x⟫ ∈
Imagek((Imagek(( Ins3k ∼ (( Ins3k Sk ∩ Ins2k Sk ) “k ℘1℘11c) ∖ (( Ins2k Ins2k Sk ⊕ ( Ins2k Ins3k Sk ∪ Ins3k SIk SIk Sk )) “k ℘1℘1℘1℘11c))
“k ℘1℘11c) ∩ ( Nn ×k V)) ∪ (
Ik ∩ ( ∼ Nn
×k V)))) | 
| 4 |   | dfphi2 4570 | 
. . . . . . . . 9
⊢  Phi y =
(((Imagek(( Ins3k ∼ (( Ins3k Sk ∩ Ins2k Sk ) “k ℘1℘11c) ∖ (( Ins2k Ins2k Sk ⊕ ( Ins2k Ins3k Sk ∪ Ins3k SIk SIk Sk )) “k ℘1℘1℘1℘11c))
“k ℘1℘11c) ∩ ( Nn ×k V)) ∪ (
Ik ∩ ( ∼ Nn
×k V))) “k y) | 
| 5 | 4 | eqeq2i 2363 | 
. . . . . . . 8
⊢ (x =  Phi y ↔ x =
(((Imagek(( Ins3k ∼ (( Ins3k Sk ∩ Ins2k Sk ) “k ℘1℘11c) ∖ (( Ins2k Ins2k Sk ⊕ ( Ins2k Ins3k Sk ∪ Ins3k SIk SIk Sk )) “k ℘1℘1℘1℘11c))
“k ℘1℘11c) ∩ ( Nn ×k V)) ∪ (
Ik ∩ ( ∼ Nn
×k V))) “k y)) | 
| 6 |   | vex 2863 | 
. . . . . . . . 9
⊢ y ∈
V | 
| 7 | 6, 2 | opkelimagek 4273 | 
. . . . . . . 8
⊢ (⟪y, x⟫
∈
Imagek((Imagek(( Ins3k ∼ (( Ins3k Sk ∩ Ins2k Sk ) “k ℘1℘11c) ∖ (( Ins2k Ins2k Sk ⊕ ( Ins2k Ins3k Sk ∪ Ins3k SIk SIk Sk )) “k ℘1℘1℘1℘11c))
“k ℘1℘11c) ∩ ( Nn ×k V)) ∪ (
Ik ∩ ( ∼ Nn
×k V))) ↔ x =
(((Imagek(( Ins3k ∼ (( Ins3k Sk ∩ Ins2k Sk ) “k ℘1℘11c) ∖ (( Ins2k Ins2k Sk ⊕ ( Ins2k Ins3k Sk ∪ Ins3k SIk SIk Sk )) “k ℘1℘1℘1℘11c))
“k ℘1℘11c) ∩ ( Nn ×k V)) ∪ (
Ik ∩ ( ∼ Nn
×k V))) “k y)) | 
| 8 | 5, 7 | bitr4i 243 | 
. . . . . . 7
⊢ (x =  Phi y ↔ ⟪y, x⟫
∈
Imagek((Imagek(( Ins3k ∼ (( Ins3k Sk ∩ Ins2k Sk ) “k ℘1℘11c) ∖ (( Ins2k Ins2k Sk ⊕ ( Ins2k Ins3k Sk ∪ Ins3k SIk SIk Sk )) “k ℘1℘1℘1℘11c))
“k ℘1℘11c) ∩ ( Nn ×k V)) ∪ (
Ik ∩ ( ∼ Nn
×k V)))) | 
| 9 | 8 | rexbii 2640 | 
. . . . . 6
⊢ (∃y ∈ A x =  Phi y ↔ ∃y ∈ A
⟪y, x⟫ ∈
Imagek((Imagek(( Ins3k ∼ (( Ins3k Sk ∩ Ins2k Sk ) “k ℘1℘11c) ∖ (( Ins2k Ins2k Sk ⊕ ( Ins2k Ins3k Sk ∪ Ins3k SIk SIk Sk )) “k ℘1℘1℘1℘11c))
“k ℘1℘11c) ∩ ( Nn ×k V)) ∪ (
Ik ∩ ( ∼ Nn
×k V)))) | 
| 10 | 9 | bicomi 193 | 
. . . . 5
⊢ (∃y ∈ A
⟪y, x⟫ ∈
Imagek((Imagek(( Ins3k ∼ (( Ins3k Sk ∩ Ins2k Sk ) “k ℘1℘11c) ∖ (( Ins2k Ins2k Sk ⊕ ( Ins2k Ins3k Sk ∪ Ins3k SIk SIk Sk )) “k ℘1℘1℘1℘11c))
“k ℘1℘11c) ∩ ( Nn ×k V)) ∪ (
Ik ∩ ( ∼ Nn
×k V))) ↔ ∃y ∈ A x =  Phi y) | 
| 11 | 3, 10 | bitri 240 | 
. . . 4
⊢ (x ∈
(Imagek((Imagek(( Ins3k ∼ (( Ins3k Sk ∩ Ins2k Sk ) “k ℘1℘11c) ∖ (( Ins2k Ins2k Sk ⊕ ( Ins2k Ins3k Sk ∪ Ins3k SIk SIk Sk )) “k ℘1℘1℘1℘11c))
“k ℘1℘11c) ∩ ( Nn ×k V)) ∪ (
Ik ∩ ( ∼ Nn
×k V))) “k A) ↔ ∃y ∈ A x =  Phi y) | 
| 12 | 11 | eqabi 2465 | 
. . 3
⊢
(Imagek((Imagek(( Ins3k ∼ (( Ins3k Sk ∩ Ins2k Sk ) “k ℘1℘11c) ∖ (( Ins2k Ins2k Sk ⊕ ( Ins2k Ins3k Sk ∪ Ins3k SIk SIk Sk )) “k ℘1℘1℘1℘11c))
“k ℘1℘11c) ∩ ( Nn ×k V)) ∪ (
Ik ∩ ( ∼ Nn
×k V))) “k A) = {x ∣ ∃y ∈ A x =  Phi y} | 
| 13 |   | dfop2lem2 4575 | 
. . 3
⊢ ( ∼ (( Ins2k Sk ⊕ Ins3k ((◡kImagek((Imagek((
Ins3k ∼ (( Ins3k Sk ∩
Ins2k Sk )
“k ℘1℘11c) ∖ ((
Ins2k Ins2k
Sk ⊕ ( Ins2k Ins3k Sk ∪ Ins3k
SIk SIk
Sk )) “k ℘1℘1℘1℘11c)) “k ℘1℘11c) ∩ ( Nn
×k V)) ∪ ( Ik ∩ ( ∼ Nn
×k V))) ∘k Sk ) ∪ ({{0c}} ×k
V))) “k ℘1℘11c) “k B) = {x ∣ ∃y
∈ B x = ( Phi y
∪ {0c})} | 
| 14 | 12, 13 | uneq12i 3417 | 
. 2
⊢
((Imagek((Imagek(( Ins3k ∼ (( Ins3k Sk ∩ Ins2k Sk ) “k ℘1℘11c) ∖ (( Ins2k Ins2k Sk ⊕ ( Ins2k Ins3k Sk ∪ Ins3k SIk SIk Sk )) “k ℘1℘1℘1℘11c))
“k ℘1℘11c) ∩ ( Nn ×k V)) ∪ (
Ik ∩ ( ∼ Nn
×k V))) “k A) ∪ ( ∼ (( Ins2k Sk ⊕ Ins3k ((◡kImagek((Imagek((
Ins3k ∼ (( Ins3k Sk ∩
Ins2k Sk )
“k ℘1℘11c) ∖ ((
Ins2k Ins2k
Sk ⊕ ( Ins2k Ins3k Sk ∪ Ins3k
SIk SIk
Sk )) “k ℘1℘1℘1℘11c)) “k ℘1℘11c) ∩ ( Nn
×k V)) ∪ ( Ik ∩ ( ∼ Nn
×k V))) ∘k Sk ) ∪ ({{0c}} ×k
V))) “k ℘1℘11c) “k B)) = ({x ∣ ∃y
∈ A x =  Phi y}
∪ {x ∣ ∃y ∈
B x = ( Phi
y ∪ {0c})}) | 
| 15 | 1, 14 | eqtr4i 2376 | 
1
⊢ 〈A, B〉 =
((Imagek((Imagek(( Ins3k ∼ (( Ins3k Sk ∩ Ins2k Sk ) “k ℘1℘11c) ∖ (( Ins2k Ins2k Sk ⊕ ( Ins2k Ins3k Sk ∪ Ins3k SIk SIk Sk )) “k ℘1℘1℘1℘11c))
“k ℘1℘11c) ∩ ( Nn ×k V)) ∪ (
Ik ∩ ( ∼ Nn
×k V))) “k A) ∪ ( ∼ (( Ins2k Sk ⊕ Ins3k ((◡kImagek((Imagek((
Ins3k ∼ (( Ins3k Sk ∩
Ins2k Sk )
“k ℘1℘11c) ∖ ((
Ins2k Ins2k
Sk ⊕ ( Ins2k Ins3k Sk ∪ Ins3k
SIk SIk
Sk )) “k ℘1℘1℘1℘11c)) “k ℘1℘11c) ∩ ( Nn
×k V)) ∪ ( Ik ∩ ( ∼ Nn
×k V))) ∘k Sk ) ∪ ({{0c}} ×k
V))) “k ℘1℘11c) “k B)) |