| Step | Hyp | Ref
 | Expression | 
| 1 |   | sikeq 4242 | 
. . 3
⊢ (x = A →
SIk x = SIk A) | 
| 2 | 1 | eleq1d 2419 | 
. 2
⊢ (x = A → (
SIk x ∈ V ↔ SIk A ∈
V)) | 
| 3 |   | ax-si 4084 | 
. . 3
⊢ ∃y∀z∀w(⟪{z},
{w}⟫ ∈ y ↔
⟪z, w⟫ ∈
x) | 
| 4 |   | inss1 3476 | 
. . . . . . . 8
⊢
((1c ×k 1c)
∩ y) ⊆ (1c ×k
1c) | 
| 5 |   | sikss1c1c 4268 | 
. . . . . . . 8
⊢  SIk x ⊆
(1c ×k
1c) | 
| 6 | 4, 5 | sikexlem 4296 | 
. . . . . . 7
⊢
(((1c ×k 1c)
∩ y) = SIk x ↔ ∀z∀w(⟪{z},
{w}⟫ ∈ ((1c ×k
1c) ∩ y) ↔
⟪{z}, {w}⟫ ∈ SIk x)) | 
| 7 |   | vex 2863 | 
. . . . . . . . . . . 12
⊢ z ∈
V | 
| 8 | 7 | snel1c 4141 | 
. . . . . . . . . . 11
⊢ {z} ∈
1c | 
| 9 |   | vex 2863 | 
. . . . . . . . . . . 12
⊢ w ∈
V | 
| 10 | 9 | snel1c 4141 | 
. . . . . . . . . . 11
⊢ {w} ∈
1c | 
| 11 |   | snex 4112 | 
. . . . . . . . . . . 12
⊢ {z} ∈
V | 
| 12 |   | snex 4112 | 
. . . . . . . . . . . 12
⊢ {w} ∈
V | 
| 13 | 11, 12 | opkelxpk 4249 | 
. . . . . . . . . . 11
⊢ (⟪{z}, {w}⟫
∈ (1c
×k 1c) ↔ ({z} ∈
1c ∧ {w} ∈
1c)) | 
| 14 | 8, 10, 13 | mpbir2an 886 | 
. . . . . . . . . 10
⊢ ⟪{z}, {w}⟫
∈ (1c
×k 1c) | 
| 15 |   | elin 3220 | 
. . . . . . . . . 10
⊢ (⟪{z}, {w}⟫
∈ ((1c
×k 1c) ∩ y) ↔ (⟪{z}, {w}⟫
∈ (1c
×k 1c) ∧ ⟪{z},
{w}⟫ ∈ y)) | 
| 16 | 14, 15 | mpbiran 884 | 
. . . . . . . . 9
⊢ (⟪{z}, {w}⟫
∈ ((1c
×k 1c) ∩ y) ↔ ⟪{z}, {w}⟫
∈ y) | 
| 17 | 7, 9 | opksnelsik 4266 | 
. . . . . . . . 9
⊢ (⟪{z}, {w}⟫
∈ SIk x ↔ ⟪z, w⟫
∈ x) | 
| 18 | 16, 17 | bibi12i 306 | 
. . . . . . . 8
⊢ ((⟪{z}, {w}⟫
∈ ((1c
×k 1c) ∩ y) ↔ ⟪{z}, {w}⟫
∈ SIk x) ↔ (⟪{z}, {w}⟫
∈ y
↔ ⟪z, w⟫ ∈
x)) | 
| 19 | 18 | 2albii 1567 | 
. . . . . . 7
⊢ (∀z∀w(⟪{z},
{w}⟫ ∈ ((1c ×k
1c) ∩ y) ↔
⟪{z}, {w}⟫ ∈ SIk x) ↔ ∀z∀w(⟪{z},
{w}⟫ ∈ y ↔
⟪z, w⟫ ∈
x)) | 
| 20 | 6, 19 | bitri 240 | 
. . . . . 6
⊢
(((1c ×k 1c)
∩ y) = SIk x ↔ ∀z∀w(⟪{z},
{w}⟫ ∈ y ↔
⟪z, w⟫ ∈
x)) | 
| 21 | 20 | biimpri 197 | 
. . . . 5
⊢ (∀z∀w(⟪{z},
{w}⟫ ∈ y ↔
⟪z, w⟫ ∈
x) → ((1c
×k 1c) ∩ y) = SIk x) | 
| 22 |   | 1cex 4143 | 
. . . . . . 7
⊢
1c ∈
V | 
| 23 | 22, 22 | xpkex 4290 | 
. . . . . 6
⊢
(1c ×k 1c)
∈ V | 
| 24 |   | vex 2863 | 
. . . . . 6
⊢ y ∈
V | 
| 25 | 23, 24 | inex 4106 | 
. . . . 5
⊢
((1c ×k 1c)
∩ y) ∈ V | 
| 26 | 21, 25 | syl6eqelr 2442 | 
. . . 4
⊢ (∀z∀w(⟪{z},
{w}⟫ ∈ y ↔
⟪z, w⟫ ∈
x) → SIk x ∈
V) | 
| 27 | 26 | exlimiv 1634 | 
. . 3
⊢ (∃y∀z∀w(⟪{z},
{w}⟫ ∈ y ↔
⟪z, w⟫ ∈
x) → SIk x ∈
V) | 
| 28 | 3, 27 | ax-mp 5 | 
. 2
⊢  SIk x ∈
V | 
| 29 | 2, 28 | vtoclg 2915 | 
1
⊢ (A ∈ V → SIk A ∈
V) |