| Step | Hyp | Ref
 | Expression | 
| 1 |   | nnsucelrlem1 4425 | 
. . . 4
⊢ {m ∣ ∀a∀x((¬
x ∈
a ∧
(a ∪ {x}) ∈ (m +c 1c)) →
a ∈
m)} ∈
V | 
| 2 |   | addceq1 4384 | 
. . . . . . . . . 10
⊢ (m = 0c → (m +c 1c) =
(0c +c
1c)) | 
| 3 |   | addcid2 4408 | 
. . . . . . . . . 10
⊢
(0c +c 1c) =
1c | 
| 4 | 2, 3 | syl6eq 2401 | 
. . . . . . . . 9
⊢ (m = 0c → (m +c 1c) =
1c) | 
| 5 | 4 | eleq2d 2420 | 
. . . . . . . 8
⊢ (m = 0c → ((a ∪ {x})
∈ (m
+c 1c) ↔ (a ∪ {x})
∈ 1c)) | 
| 6 |   | el1c 4140 | 
. . . . . . . 8
⊢ ((a ∪ {x})
∈ 1c ↔ ∃y(a ∪ {x}) =
{y}) | 
| 7 | 5, 6 | syl6bb 252 | 
. . . . . . 7
⊢ (m = 0c → ((a ∪ {x})
∈ (m
+c 1c) ↔ ∃y(a ∪ {x}) =
{y})) | 
| 8 | 7 | anbi2d 684 | 
. . . . . 6
⊢ (m = 0c → ((¬ x ∈ a ∧ (a ∪ {x})
∈ (m
+c 1c)) ↔ (¬ x ∈ a ∧ ∃y(a ∪ {x}) =
{y}))) | 
| 9 |   | eleq2 2414 | 
. . . . . . 7
⊢ (m = 0c → (a ∈ m ↔ a ∈ 0c)) | 
| 10 |   | df-0c 4378 | 
. . . . . . . . 9
⊢
0c = {∅} | 
| 11 | 10 | eleq2i 2417 | 
. . . . . . . 8
⊢ (a ∈
0c ↔ a ∈ {∅}) | 
| 12 |   | vex 2863 | 
. . . . . . . . 9
⊢ a ∈
V | 
| 13 | 12 | elsnc 3757 | 
. . . . . . . 8
⊢ (a ∈ {∅} ↔ a =
∅) | 
| 14 | 11, 13 | bitri 240 | 
. . . . . . 7
⊢ (a ∈
0c ↔ a = ∅) | 
| 15 | 9, 14 | syl6bb 252 | 
. . . . . 6
⊢ (m = 0c → (a ∈ m ↔ a =
∅)) | 
| 16 | 8, 15 | imbi12d 311 | 
. . . . 5
⊢ (m = 0c → (((¬ x ∈ a ∧ (a ∪ {x})
∈ (m
+c 1c)) → a ∈ m) ↔ ((¬ x ∈ a ∧ ∃y(a ∪ {x}) =
{y}) → a = ∅))) | 
| 17 | 16 | 2albidv 1627 | 
. . . 4
⊢ (m = 0c → (∀a∀x((¬
x ∈
a ∧
(a ∪ {x}) ∈ (m +c 1c)) →
a ∈
m) ↔ ∀a∀x((¬
x ∈
a ∧ ∃y(a ∪ {x}) =
{y}) → a = ∅))) | 
| 18 |   | addceq1 4384 | 
. . . . . . . . 9
⊢ (m = n →
(m +c
1c) = (n
+c 1c)) | 
| 19 | 18 | eleq2d 2420 | 
. . . . . . . 8
⊢ (m = n →
((a ∪ {x}) ∈ (m +c 1c) ↔
(a ∪ {x}) ∈ (n +c
1c))) | 
| 20 | 19 | anbi2d 684 | 
. . . . . . 7
⊢ (m = n →
((¬ x ∈ a ∧ (a ∪
{x}) ∈
(m +c
1c)) ↔ (¬ x
∈ a ∧ (a ∪
{x}) ∈
(n +c
1c)))) | 
| 21 |   | eleq2 2414 | 
. . . . . . 7
⊢ (m = n →
(a ∈
m ↔ a ∈ n)) | 
| 22 | 20, 21 | imbi12d 311 | 
. . . . . 6
⊢ (m = n →
(((¬ x ∈ a ∧ (a ∪
{x}) ∈
(m +c
1c)) → a ∈ m) ↔
((¬ x ∈ a ∧ (a ∪
{x}) ∈
(n +c
1c)) → a ∈ n))) | 
| 23 | 22 | 2albidv 1627 | 
. . . . 5
⊢ (m = n →
(∀a∀x((¬ x ∈ a ∧ (a ∪
{x}) ∈
(m +c
1c)) → a ∈ m) ↔
∀a∀x((¬
x ∈
a ∧
(a ∪ {x}) ∈ (n +c 1c)) →
a ∈
n))) | 
| 24 |   | eleq12 2415 | 
. . . . . . . . . 10
⊢ ((x = z ∧ a = c) → (x
∈ a
↔ z ∈ c)) | 
| 25 | 24 | ancoms 439 | 
. . . . . . . . 9
⊢ ((a = c ∧ x = z) → (x
∈ a
↔ z ∈ c)) | 
| 26 | 25 | notbid 285 | 
. . . . . . . 8
⊢ ((a = c ∧ x = z) → (¬ x ∈ a ↔ ¬ z
∈ c)) | 
| 27 |   | sneq 3745 | 
. . . . . . . . . 10
⊢ (x = z →
{x} = {z}) | 
| 28 |   | uneq12 3414 | 
. . . . . . . . . 10
⊢ ((a = c ∧ {x} =
{z}) → (a ∪ {x}) =
(c ∪ {z})) | 
| 29 | 27, 28 | sylan2 460 | 
. . . . . . . . 9
⊢ ((a = c ∧ x = z) → (a
∪ {x}) = (c ∪ {z})) | 
| 30 | 29 | eleq1d 2419 | 
. . . . . . . 8
⊢ ((a = c ∧ x = z) → ((a
∪ {x}) ∈ (n
+c 1c) ↔ (c ∪ {z})
∈ (n
+c 1c))) | 
| 31 | 26, 30 | anbi12d 691 | 
. . . . . . 7
⊢ ((a = c ∧ x = z) → ((¬ x ∈ a ∧ (a ∪ {x})
∈ (n
+c 1c)) ↔ (¬ z ∈ c ∧ (c ∪ {z})
∈ (n
+c 1c)))) | 
| 32 |   | eleq1 2413 | 
. . . . . . . 8
⊢ (a = c →
(a ∈
n ↔ c ∈ n)) | 
| 33 | 32 | adantr 451 | 
. . . . . . 7
⊢ ((a = c ∧ x = z) → (a
∈ n
↔ c ∈ n)) | 
| 34 | 31, 33 | imbi12d 311 | 
. . . . . 6
⊢ ((a = c ∧ x = z) → (((¬ x ∈ a ∧ (a ∪ {x})
∈ (n
+c 1c)) → a ∈ n) ↔ ((¬ z ∈ c ∧ (c ∪ {z})
∈ (n
+c 1c)) → c ∈ n))) | 
| 35 | 34 | cbval2v 2006 | 
. . . . 5
⊢ (∀a∀x((¬
x ∈
a ∧
(a ∪ {x}) ∈ (n +c 1c)) →
a ∈
n) ↔ ∀c∀z((¬
z ∈
c ∧
(c ∪ {z}) ∈ (n +c 1c)) →
c ∈
n)) | 
| 36 | 23, 35 | syl6bb 252 | 
. . . 4
⊢ (m = n →
(∀a∀x((¬ x ∈ a ∧ (a ∪
{x}) ∈
(m +c
1c)) → a ∈ m) ↔
∀c∀z((¬
z ∈
c ∧
(c ∪ {z}) ∈ (n +c 1c)) →
c ∈
n))) | 
| 37 |   | addceq1 4384 | 
. . . . . . . 8
⊢ (m = (n
+c 1c) → (m +c 1c) =
((n +c
1c) +c
1c)) | 
| 38 | 37 | eleq2d 2420 | 
. . . . . . 7
⊢ (m = (n
+c 1c) → ((a ∪ {x})
∈ (m
+c 1c) ↔ (a ∪ {x})
∈ ((n
+c 1c) +c
1c))) | 
| 39 | 38 | anbi2d 684 | 
. . . . . 6
⊢ (m = (n
+c 1c) → ((¬ x ∈ a ∧ (a ∪ {x})
∈ (m
+c 1c)) ↔ (¬ x ∈ a ∧ (a ∪ {x})
∈ ((n
+c 1c) +c
1c)))) | 
| 40 |   | eleq2 2414 | 
. . . . . 6
⊢ (m = (n
+c 1c) → (a ∈ m ↔ a ∈ (n
+c 1c))) | 
| 41 | 39, 40 | imbi12d 311 | 
. . . . 5
⊢ (m = (n
+c 1c) → (((¬ x ∈ a ∧ (a ∪ {x})
∈ (m
+c 1c)) → a ∈ m) ↔ ((¬ x ∈ a ∧ (a ∪ {x})
∈ ((n
+c 1c) +c
1c)) → a ∈ (n
+c 1c)))) | 
| 42 | 41 | 2albidv 1627 | 
. . . 4
⊢ (m = (n
+c 1c) → (∀a∀x((¬
x ∈
a ∧
(a ∪ {x}) ∈ (m +c 1c)) →
a ∈
m) ↔ ∀a∀x((¬
x ∈
a ∧
(a ∪ {x}) ∈ ((n +c 1c)
+c 1c)) → a ∈ (n +c
1c)))) | 
| 43 |   | addceq1 4384 | 
. . . . . . . 8
⊢ (m = M →
(m +c
1c) = (M
+c 1c)) | 
| 44 | 43 | eleq2d 2420 | 
. . . . . . 7
⊢ (m = M →
((a ∪ {x}) ∈ (m +c 1c) ↔
(a ∪ {x}) ∈ (M +c
1c))) | 
| 45 | 44 | anbi2d 684 | 
. . . . . 6
⊢ (m = M →
((¬ x ∈ a ∧ (a ∪
{x}) ∈
(m +c
1c)) ↔ (¬ x
∈ a ∧ (a ∪
{x}) ∈
(M +c
1c)))) | 
| 46 |   | eleq2 2414 | 
. . . . . 6
⊢ (m = M →
(a ∈
m ↔ a ∈ M)) | 
| 47 | 45, 46 | imbi12d 311 | 
. . . . 5
⊢ (m = M →
(((¬ x ∈ a ∧ (a ∪
{x}) ∈
(m +c
1c)) → a ∈ m) ↔
((¬ x ∈ a ∧ (a ∪
{x}) ∈
(M +c
1c)) → a ∈ M))) | 
| 48 | 47 | 2albidv 1627 | 
. . . 4
⊢ (m = M →
(∀a∀x((¬ x ∈ a ∧ (a ∪
{x}) ∈
(m +c
1c)) → a ∈ m) ↔
∀a∀x((¬
x ∈
a ∧
(a ∪ {x}) ∈ (M +c 1c)) →
a ∈
M))) | 
| 49 |   | vex 2863 | 
. . . . . . . . . . 11
⊢ x ∈
V | 
| 50 | 49 | unsneqsn 3888 | 
. . . . . . . . . 10
⊢ ((a ∪ {x}) =
{y} → (a = ∅  ∨ a = {x})) | 
| 51 | 50 | ord 366 | 
. . . . . . . . 9
⊢ ((a ∪ {x}) =
{y} → (¬ a = ∅ →
a = {x})) | 
| 52 | 49 | snid 3761 | 
. . . . . . . . . 10
⊢ x ∈ {x} | 
| 53 |   | eleq2 2414 | 
. . . . . . . . . 10
⊢ (a = {x} →
(x ∈
a ↔ x ∈ {x})) | 
| 54 | 52, 53 | mpbiri 224 | 
. . . . . . . . 9
⊢ (a = {x} →
x ∈
a) | 
| 55 | 51, 54 | syl6 29 | 
. . . . . . . 8
⊢ ((a ∪ {x}) =
{y} → (¬ a = ∅ →
x ∈
a)) | 
| 56 | 55 | con1d 116 | 
. . . . . . 7
⊢ ((a ∪ {x}) =
{y} → (¬ x ∈ a → a =
∅)) | 
| 57 | 56 | exlimiv 1634 | 
. . . . . 6
⊢ (∃y(a ∪ {x}) =
{y} → (¬ x ∈ a → a =
∅)) | 
| 58 | 57 | impcom 419 | 
. . . . 5
⊢ ((¬ x ∈ a ∧ ∃y(a ∪ {x}) =
{y}) → a = ∅) | 
| 59 | 58 | gen2 1547 | 
. . . 4
⊢ ∀a∀x((¬
x ∈
a ∧ ∃y(a ∪ {x}) =
{y}) → a = ∅) | 
| 60 |   | elsuc 4414 | 
. . . . . . . . 9
⊢ ((a ∪ {x})
∈ ((n
+c 1c) +c
1c) ↔ ∃b ∈ (n +c 1c)∃y ∈ ∼ b(a ∪
{x}) = (b ∪ {y})) | 
| 61 |   | vex 2863 | 
. . . . . . . . . . . . 13
⊢ y ∈
V | 
| 62 | 61 | elcompl 3226 | 
. . . . . . . . . . . 12
⊢ (y ∈ ∼ b ↔ ¬ y
∈ b) | 
| 63 | 62 | anbi2i 675 | 
. . . . . . . . . . 11
⊢ ((b ∈ (n +c 1c) ∧ y ∈ ∼ b)
↔ (b ∈ (n
+c 1c) ∧
¬ y ∈
b)) | 
| 64 |   | simprrl 740 | 
. . . . . . . . . . . . . . . . . . 19
⊢ ((x = y ∧ ((b ∈ (n
+c 1c) ∧
¬ y ∈
b) ∧
((a ∪ {x}) = (b ∪
{y}) ∧
¬ x ∈
a))) → (a ∪ {x}) =
(b ∪ {y})) | 
| 65 |   | sneq 3745 | 
. . . . . . . . . . . . . . . . . . . 20
⊢ (x = y →
{x} = {y}) | 
| 66 | 65 | adantr 451 | 
. . . . . . . . . . . . . . . . . . 19
⊢ ((x = y ∧ ((b ∈ (n
+c 1c) ∧
¬ y ∈
b) ∧
((a ∪ {x}) = (b ∪
{y}) ∧
¬ x ∈
a))) → {x} = {y}) | 
| 67 | 64, 66 | difeq12d 3387 | 
. . . . . . . . . . . . . . . . . 18
⊢ ((x = y ∧ ((b ∈ (n
+c 1c) ∧
¬ y ∈
b) ∧
((a ∪ {x}) = (b ∪
{y}) ∧
¬ x ∈
a))) → ((a ∪ {x})
∖ {x}) =
((b ∪ {y}) ∖ {y})) | 
| 68 |   | simprrr 741 | 
. . . . . . . . . . . . . . . . . . 19
⊢ ((x = y ∧ ((b ∈ (n
+c 1c) ∧
¬ y ∈
b) ∧
((a ∪ {x}) = (b ∪
{y}) ∧
¬ x ∈
a))) → ¬ x ∈ a) | 
| 69 |   | nnsucelrlem2 4426 | 
. . . . . . . . . . . . . . . . . . 19
⊢ (¬ x ∈ a → ((a
∪ {x}) ∖ {x}) =
a) | 
| 70 | 68, 69 | syl 15 | 
. . . . . . . . . . . . . . . . . 18
⊢ ((x = y ∧ ((b ∈ (n
+c 1c) ∧
¬ y ∈
b) ∧
((a ∪ {x}) = (b ∪
{y}) ∧
¬ x ∈
a))) → ((a ∪ {x})
∖ {x}) =
a) | 
| 71 |   | simprlr 739 | 
. . . . . . . . . . . . . . . . . . 19
⊢ ((x = y ∧ ((b ∈ (n
+c 1c) ∧
¬ y ∈
b) ∧
((a ∪ {x}) = (b ∪
{y}) ∧
¬ x ∈
a))) → ¬ y ∈ b) | 
| 72 |   | nnsucelrlem2 4426 | 
. . . . . . . . . . . . . . . . . . 19
⊢ (¬ y ∈ b → ((b
∪ {y}) ∖ {y}) =
b) | 
| 73 | 71, 72 | syl 15 | 
. . . . . . . . . . . . . . . . . 18
⊢ ((x = y ∧ ((b ∈ (n
+c 1c) ∧
¬ y ∈
b) ∧
((a ∪ {x}) = (b ∪
{y}) ∧
¬ x ∈
a))) → ((b ∪ {y})
∖ {y}) =
b) | 
| 74 | 67, 70, 73 | 3eqtr3d 2393 | 
. . . . . . . . . . . . . . . . 17
⊢ ((x = y ∧ ((b ∈ (n
+c 1c) ∧
¬ y ∈
b) ∧
((a ∪ {x}) = (b ∪
{y}) ∧
¬ x ∈
a))) → a = b) | 
| 75 |   | simprll 738 | 
. . . . . . . . . . . . . . . . 17
⊢ ((x = y ∧ ((b ∈ (n
+c 1c) ∧
¬ y ∈
b) ∧
((a ∪ {x}) = (b ∪
{y}) ∧
¬ x ∈
a))) → b ∈ (n +c
1c)) | 
| 76 | 74, 75 | eqeltrd 2427 | 
. . . . . . . . . . . . . . . 16
⊢ ((x = y ∧ ((b ∈ (n
+c 1c) ∧
¬ y ∈
b) ∧
((a ∪ {x}) = (b ∪
{y}) ∧
¬ x ∈
a))) → a ∈ (n +c
1c)) | 
| 77 | 76 | 3adantr1 1114 | 
. . . . . . . . . . . . . . 15
⊢ ((x = y ∧ (∀c∀z((¬ z ∈ c ∧ (c ∪
{z}) ∈
(n +c
1c)) → c ∈ n) ∧ (b ∈ (n
+c 1c) ∧
¬ y ∈
b) ∧
((a ∪ {x}) = (b ∪
{y}) ∧
¬ x ∈
a))) → a ∈ (n +c
1c)) | 
| 78 | 77 | ex 423 | 
. . . . . . . . . . . . . 14
⊢ (x = y →
((∀c∀z((¬ z ∈ c ∧ (c ∪
{z}) ∈
(n +c
1c)) → c ∈ n) ∧ (b ∈ (n
+c 1c) ∧
¬ y ∈
b) ∧
((a ∪ {x}) = (b ∪
{y}) ∧
¬ x ∈
a)) → a ∈ (n +c
1c))) | 
| 79 |   | simpl 443 | 
. . . . . . . . . . . . . . . . 17
⊢ ((x ≠ y ∧ (∀c∀z((¬ z ∈ c ∧ (c ∪
{z}) ∈
(n +c
1c)) → c ∈ n) ∧ (b ∈ (n
+c 1c) ∧
¬ y ∈
b) ∧
((a ∪ {x}) = (b ∪
{y}) ∧
¬ x ∈
a))) → x ≠ y) | 
| 80 |   | simpr3l 1016 | 
. . . . . . . . . . . . . . . . 17
⊢ ((x ≠ y ∧ (∀c∀z((¬ z ∈ c ∧ (c ∪
{z}) ∈
(n +c
1c)) → c ∈ n) ∧ (b ∈ (n
+c 1c) ∧
¬ y ∈
b) ∧
((a ∪ {x}) = (b ∪
{y}) ∧
¬ x ∈
a))) → (a ∪ {x}) =
(b ∪ {y})) | 
| 81 |   | simpr2r 1015 | 
. . . . . . . . . . . . . . . . 17
⊢ ((x ≠ y ∧ (∀c∀z((¬ z ∈ c ∧ (c ∪
{z}) ∈
(n +c
1c)) → c ∈ n) ∧ (b ∈ (n
+c 1c) ∧
¬ y ∈
b) ∧
((a ∪ {x}) = (b ∪
{y}) ∧
¬ x ∈
a))) → ¬ y ∈ b) | 
| 82 | 49 | nnsucelrlem3 4427 | 
. . . . . . . . . . . . . . . . 17
⊢ ((x ≠ y ∧ (a ∪
{x}) = (b ∪ {y})
∧ ¬ y
∈ b)
→ b = ((a ∖ {y}) ∪ {x})) | 
| 83 | 79, 80, 81, 82 | syl3anc 1182 | 
. . . . . . . . . . . . . . . 16
⊢ ((x ≠ y ∧ (∀c∀z((¬ z ∈ c ∧ (c ∪
{z}) ∈
(n +c
1c)) → c ∈ n) ∧ (b ∈ (n
+c 1c) ∧
¬ y ∈
b) ∧
((a ∪ {x}) = (b ∪
{y}) ∧
¬ x ∈
a))) → b = ((a ∖ {y}) ∪
{x})) | 
| 84 |   | simp22r 1075 | 
. . . . . . . . . . . . . . . . . . 19
⊢ ((x ≠ y ∧ (∀c∀z((¬ z ∈ c ∧ (c ∪
{z}) ∈
(n +c
1c)) → c ∈ n) ∧ (b ∈ (n
+c 1c) ∧
¬ y ∈
b) ∧
((a ∪ {x}) = (b ∪
{y}) ∧
¬ x ∈
a)) ∧
b = ((a
∖ {y})
∪ {x})) → ¬ y ∈ b) | 
| 85 |   | difsn 3846 | 
. . . . . . . . . . . . . . . . . . . . . . . 24
⊢ (¬ y ∈ a → (a
∖ {y}) =
a) | 
| 86 | 85 | uneq1d 3418 | 
. . . . . . . . . . . . . . . . . . . . . . 23
⊢ (¬ y ∈ a → ((a
∖ {y})
∪ {x}) = (a ∪ {x})) | 
| 87 | 86 | eqeq2d 2364 | 
. . . . . . . . . . . . . . . . . . . . . 22
⊢ (¬ y ∈ a → (b =
((a ∖
{y}) ∪ {x}) ↔ b =
(a ∪ {x}))) | 
| 88 | 87 | biimpcd 215 | 
. . . . . . . . . . . . . . . . . . . . 21
⊢ (b = ((a ∖ {y}) ∪
{x}) → (¬ y ∈ a → b =
(a ∪ {x}))) | 
| 89 | 88 | 3ad2ant3 978 | 
. . . . . . . . . . . . . . . . . . . 20
⊢ ((x ≠ y ∧ (∀c∀z((¬ z ∈ c ∧ (c ∪
{z}) ∈
(n +c
1c)) → c ∈ n) ∧ (b ∈ (n
+c 1c) ∧
¬ y ∈
b) ∧
((a ∪ {x}) = (b ∪
{y}) ∧
¬ x ∈
a)) ∧
b = ((a
∖ {y})
∪ {x})) → (¬ y ∈ a → b =
(a ∪ {x}))) | 
| 90 |   | simp23l 1076 | 
. . . . . . . . . . . . . . . . . . . . . 22
⊢ ((x ≠ y ∧ (∀c∀z((¬ z ∈ c ∧ (c ∪
{z}) ∈
(n +c
1c)) → c ∈ n) ∧ (b ∈ (n
+c 1c) ∧
¬ y ∈
b) ∧
((a ∪ {x}) = (b ∪
{y}) ∧
¬ x ∈
a)) ∧
b = ((a
∖ {y})
∪ {x})) → (a ∪ {x}) =
(b ∪ {y})) | 
| 91 | 90 | eqeq2d 2364 | 
. . . . . . . . . . . . . . . . . . . . 21
⊢ ((x ≠ y ∧ (∀c∀z((¬ z ∈ c ∧ (c ∪
{z}) ∈
(n +c
1c)) → c ∈ n) ∧ (b ∈ (n
+c 1c) ∧
¬ y ∈
b) ∧
((a ∪ {x}) = (b ∪
{y}) ∧
¬ x ∈
a)) ∧
b = ((a
∖ {y})
∪ {x})) → (b = (a ∪
{x}) ↔ b = (b ∪
{y}))) | 
| 92 | 61 | snss 3839 | 
. . . . . . . . . . . . . . . . . . . . . . . 24
⊢ (y ∈ b ↔ {y}
⊆ b) | 
| 93 |   | ssequn2 3437 | 
. . . . . . . . . . . . . . . . . . . . . . . 24
⊢ ({y} ⊆ b ↔ (b
∪ {y}) = b) | 
| 94 | 92, 93 | bitr2i 241 | 
. . . . . . . . . . . . . . . . . . . . . . 23
⊢ ((b ∪ {y}) =
b ↔ y ∈ b) | 
| 95 | 94 | biimpi 186 | 
. . . . . . . . . . . . . . . . . . . . . 22
⊢ ((b ∪ {y}) =
b → y ∈ b) | 
| 96 | 95 | eqcoms 2356 | 
. . . . . . . . . . . . . . . . . . . . 21
⊢ (b = (b ∪
{y}) → y ∈ b) | 
| 97 | 91, 96 | syl6bi 219 | 
. . . . . . . . . . . . . . . . . . . 20
⊢ ((x ≠ y ∧ (∀c∀z((¬ z ∈ c ∧ (c ∪
{z}) ∈
(n +c
1c)) → c ∈ n) ∧ (b ∈ (n
+c 1c) ∧
¬ y ∈
b) ∧
((a ∪ {x}) = (b ∪
{y}) ∧
¬ x ∈
a)) ∧
b = ((a
∖ {y})
∪ {x})) → (b = (a ∪
{x}) → y ∈ b)) | 
| 98 | 89, 97 | syld 40 | 
. . . . . . . . . . . . . . . . . . 19
⊢ ((x ≠ y ∧ (∀c∀z((¬ z ∈ c ∧ (c ∪
{z}) ∈
(n +c
1c)) → c ∈ n) ∧ (b ∈ (n
+c 1c) ∧
¬ y ∈
b) ∧
((a ∪ {x}) = (b ∪
{y}) ∧
¬ x ∈
a)) ∧
b = ((a
∖ {y})
∪ {x})) → (¬ y ∈ a → y ∈ b)) | 
| 99 | 84, 98 | mt3d 117 | 
. . . . . . . . . . . . . . . . . 18
⊢ ((x ≠ y ∧ (∀c∀z((¬ z ∈ c ∧ (c ∪
{z}) ∈
(n +c
1c)) → c ∈ n) ∧ (b ∈ (n
+c 1c) ∧
¬ y ∈
b) ∧
((a ∪ {x}) = (b ∪
{y}) ∧
¬ x ∈
a)) ∧
b = ((a
∖ {y})
∪ {x})) → y ∈ a) | 
| 100 |   | nnsucelrlem4 4428 | 
. . . . . . . . . . . . . . . . . 18
⊢ (y ∈ a → ((a
∖ {y})
∪ {y}) = a) | 
| 101 | 99, 100 | syl 15 | 
. . . . . . . . . . . . . . . . 17
⊢ ((x ≠ y ∧ (∀c∀z((¬ z ∈ c ∧ (c ∪
{z}) ∈
(n +c
1c)) → c ∈ n) ∧ (b ∈ (n
+c 1c) ∧
¬ y ∈
b) ∧
((a ∪ {x}) = (b ∪
{y}) ∧
¬ x ∈
a)) ∧
b = ((a
∖ {y})
∪ {x})) → ((a ∖ {y}) ∪ {y}) =
a) | 
| 102 |   | simpl3r 1011 | 
. . . . . . . . . . . . . . . . . . . . 21
⊢ (((∀c∀z((¬
z ∈
c ∧
(c ∪ {z}) ∈ (n +c 1c)) →
c ∈
n) ∧
(b ∈
(n +c
1c) ∧ ¬ y ∈ b) ∧ ((a ∪ {x}) =
(b ∪ {y}) ∧ ¬
x ∈
a)) ∧
b = ((a
∖ {y})
∪ {x})) → ¬ x ∈ a) | 
| 103 |   | difss 3394 | 
. . . . . . . . . . . . . . . . . . . . . 22
⊢ (a ∖ {y}) ⊆ a | 
| 104 | 103 | sseli 3270 | 
. . . . . . . . . . . . . . . . . . . . 21
⊢ (x ∈ (a ∖ {y}) → x
∈ a) | 
| 105 | 102, 104 | nsyl 113 | 
. . . . . . . . . . . . . . . . . . . 20
⊢ (((∀c∀z((¬
z ∈
c ∧
(c ∪ {z}) ∈ (n +c 1c)) →
c ∈
n) ∧
(b ∈
(n +c
1c) ∧ ¬ y ∈ b) ∧ ((a ∪ {x}) =
(b ∪ {y}) ∧ ¬
x ∈
a)) ∧
b = ((a
∖ {y})
∪ {x})) → ¬ x ∈ (a ∖ {y})) | 
| 106 |   | simp2l 981 | 
. . . . . . . . . . . . . . . . . . . . 21
⊢ ((∀c∀z((¬
z ∈
c ∧
(c ∪ {z}) ∈ (n +c 1c)) →
c ∈
n) ∧
(b ∈
(n +c
1c) ∧ ¬ y ∈ b) ∧ ((a ∪ {x}) =
(b ∪ {y}) ∧ ¬
x ∈
a)) → b ∈ (n +c
1c)) | 
| 107 |   | eleq1 2413 | 
. . . . . . . . . . . . . . . . . . . . . 22
⊢ (b = ((a ∖ {y}) ∪
{x}) → (b ∈ (n +c 1c) ↔
((a ∖
{y}) ∪ {x}) ∈ (n +c
1c))) | 
| 108 | 107 | biimpd 198 | 
. . . . . . . . . . . . . . . . . . . . 21
⊢ (b = ((a ∖ {y}) ∪
{x}) → (b ∈ (n +c 1c) →
((a ∖
{y}) ∪ {x}) ∈ (n +c
1c))) | 
| 109 | 106, 108 | mpan9 455 | 
. . . . . . . . . . . . . . . . . . . 20
⊢ (((∀c∀z((¬
z ∈
c ∧
(c ∪ {z}) ∈ (n +c 1c)) →
c ∈
n) ∧
(b ∈
(n +c
1c) ∧ ¬ y ∈ b) ∧ ((a ∪ {x}) =
(b ∪ {y}) ∧ ¬
x ∈
a)) ∧
b = ((a
∖ {y})
∪ {x})) → ((a ∖ {y}) ∪ {x})
∈ (n
+c 1c)) | 
| 110 |   | simpl1 958 | 
. . . . . . . . . . . . . . . . . . . . 21
⊢ (((∀c∀z((¬
z ∈
c ∧
(c ∪ {z}) ∈ (n +c 1c)) →
c ∈
n) ∧
(b ∈
(n +c
1c) ∧ ¬ y ∈ b) ∧ ((a ∪ {x}) =
(b ∪ {y}) ∧ ¬
x ∈
a)) ∧
b = ((a
∖ {y})
∪ {x})) → ∀c∀z((¬
z ∈
c ∧
(c ∪ {z}) ∈ (n +c 1c)) →
c ∈
n)) | 
| 111 |   | snex 4112 | 
. . . . . . . . . . . . . . . . . . . . . . 23
⊢ {y} ∈
V | 
| 112 | 12, 111 | difex 4108 | 
. . . . . . . . . . . . . . . . . . . . . 22
⊢ (a ∖ {y}) ∈
V | 
| 113 |   | eleq12 2415 | 
. . . . . . . . . . . . . . . . . . . . . . . . . . 27
⊢ ((z = x ∧ c = (a ∖ {y})) → (z
∈ c
↔ x ∈ (a ∖ {y}))) | 
| 114 | 113 | ancoms 439 | 
. . . . . . . . . . . . . . . . . . . . . . . . . 26
⊢ ((c = (a ∖ {y}) ∧ z = x) → (z
∈ c
↔ x ∈ (a ∖ {y}))) | 
| 115 | 114 | notbid 285 | 
. . . . . . . . . . . . . . . . . . . . . . . . 25
⊢ ((c = (a ∖ {y}) ∧ z = x) → (¬ z ∈ c ↔ ¬ x
∈ (a
∖ {y}))) | 
| 116 |   | sneq 3745 | 
. . . . . . . . . . . . . . . . . . . . . . . . . . 27
⊢ (z = x →
{z} = {x}) | 
| 117 |   | uneq12 3414 | 
. . . . . . . . . . . . . . . . . . . . . . . . . . 27
⊢ ((c = (a ∖ {y}) ∧ {z} =
{x}) → (c ∪ {z}) =
((a ∖
{y}) ∪ {x})) | 
| 118 | 116, 117 | sylan2 460 | 
. . . . . . . . . . . . . . . . . . . . . . . . . 26
⊢ ((c = (a ∖ {y}) ∧ z = x) → (c
∪ {z}) = ((a ∖ {y}) ∪ {x})) | 
| 119 | 118 | eleq1d 2419 | 
. . . . . . . . . . . . . . . . . . . . . . . . 25
⊢ ((c = (a ∖ {y}) ∧ z = x) → ((c
∪ {z}) ∈ (n
+c 1c) ↔ ((a ∖ {y}) ∪ {x})
∈ (n
+c 1c))) | 
| 120 | 115, 119 | anbi12d 691 | 
. . . . . . . . . . . . . . . . . . . . . . . 24
⊢ ((c = (a ∖ {y}) ∧ z = x) → ((¬ z ∈ c ∧ (c ∪ {z})
∈ (n
+c 1c)) ↔ (¬ x ∈ (a ∖ {y}) ∧ ((a ∖ {y}) ∪ {x})
∈ (n
+c 1c)))) | 
| 121 |   | eleq1 2413 | 
. . . . . . . . . . . . . . . . . . . . . . . . 25
⊢ (c = (a ∖ {y}) →
(c ∈
n ↔ (a ∖ {y}) ∈ n)) | 
| 122 | 121 | adantr 451 | 
. . . . . . . . . . . . . . . . . . . . . . . 24
⊢ ((c = (a ∖ {y}) ∧ z = x) → (c
∈ n
↔ (a ∖ {y}) ∈ n)) | 
| 123 | 120, 122 | imbi12d 311 | 
. . . . . . . . . . . . . . . . . . . . . . 23
⊢ ((c = (a ∖ {y}) ∧ z = x) → (((¬ z ∈ c ∧ (c ∪ {z})
∈ (n
+c 1c)) → c ∈ n) ↔ ((¬ x ∈ (a ∖ {y}) ∧ ((a ∖ {y}) ∪ {x})
∈ (n
+c 1c)) → (a ∖ {y}) ∈ n))) | 
| 124 | 123 | spc2gv 2943 | 
. . . . . . . . . . . . . . . . . . . . . 22
⊢ (((a ∖ {y}) ∈ V ∧ x ∈ V) → (∀c∀z((¬
z ∈
c ∧
(c ∪ {z}) ∈ (n +c 1c)) →
c ∈
n) → ((¬ x ∈ (a ∖ {y}) ∧ ((a ∖ {y}) ∪ {x})
∈ (n
+c 1c)) → (a ∖ {y}) ∈ n))) | 
| 125 | 112, 49, 124 | mp2an 653 | 
. . . . . . . . . . . . . . . . . . . . 21
⊢ (∀c∀z((¬
z ∈
c ∧
(c ∪ {z}) ∈ (n +c 1c)) →
c ∈
n) → ((¬ x ∈ (a ∖ {y}) ∧ ((a ∖ {y}) ∪ {x})
∈ (n
+c 1c)) → (a ∖ {y}) ∈ n)) | 
| 126 | 110, 125 | syl 15 | 
. . . . . . . . . . . . . . . . . . . 20
⊢ (((∀c∀z((¬
z ∈
c ∧
(c ∪ {z}) ∈ (n +c 1c)) →
c ∈
n) ∧
(b ∈
(n +c
1c) ∧ ¬ y ∈ b) ∧ ((a ∪ {x}) =
(b ∪ {y}) ∧ ¬
x ∈
a)) ∧
b = ((a
∖ {y})
∪ {x})) → ((¬ x ∈ (a ∖ {y}) ∧ ((a ∖ {y}) ∪ {x})
∈ (n
+c 1c)) → (a ∖ {y}) ∈ n)) | 
| 127 | 105, 109,
126 | mp2and 660 | 
. . . . . . . . . . . . . . . . . . 19
⊢ (((∀c∀z((¬
z ∈
c ∧
(c ∪ {z}) ∈ (n +c 1c)) →
c ∈
n) ∧
(b ∈
(n +c
1c) ∧ ¬ y ∈ b) ∧ ((a ∪ {x}) =
(b ∪ {y}) ∧ ¬
x ∈
a)) ∧
b = ((a
∖ {y})
∪ {x})) → (a ∖ {y}) ∈ n) | 
| 128 | 127 | 3adant1 973 | 
. . . . . . . . . . . . . . . . . 18
⊢ ((x ≠ y ∧ (∀c∀z((¬ z ∈ c ∧ (c ∪
{z}) ∈
(n +c
1c)) → c ∈ n) ∧ (b ∈ (n
+c 1c) ∧
¬ y ∈
b) ∧
((a ∪ {x}) = (b ∪
{y}) ∧
¬ x ∈
a)) ∧
b = ((a
∖ {y})
∪ {x})) → (a ∖ {y}) ∈ n) | 
| 129 | 61 | snid 3761 | 
. . . . . . . . . . . . . . . . . . . . 21
⊢ y ∈ {y} | 
| 130 |   | eldif 3222 | 
. . . . . . . . . . . . . . . . . . . . . 22
⊢ (y ∈ (a ∖ {y}) ↔ (y
∈ a ∧ ¬ y ∈ {y})) | 
| 131 | 130 | simprbi 450 | 
. . . . . . . . . . . . . . . . . . . . 21
⊢ (y ∈ (a ∖ {y}) → ¬ y ∈ {y}) | 
| 132 | 129, 131 | mt2 170 | 
. . . . . . . . . . . . . . . . . . . 20
⊢  ¬ y ∈ (a ∖ {y}) | 
| 133 | 61 | elcompl 3226 | 
. . . . . . . . . . . . . . . . . . . 20
⊢ (y ∈ ∼
(a ∖
{y}) ↔ ¬ y ∈ (a ∖ {y})) | 
| 134 | 132, 133 | mpbir 200 | 
. . . . . . . . . . . . . . . . . . 19
⊢ y ∈ ∼
(a ∖
{y}) | 
| 135 |   | eqid 2353 | 
. . . . . . . . . . . . . . . . . . 19
⊢ ((a ∖ {y}) ∪ {y}) =
((a ∖
{y}) ∪ {y}) | 
| 136 |   | sneq 3745 | 
. . . . . . . . . . . . . . . . . . . . . 22
⊢ (w = y →
{w} = {y}) | 
| 137 | 136 | uneq2d 3419 | 
. . . . . . . . . . . . . . . . . . . . 21
⊢ (w = y →
((a ∖
{y}) ∪ {w}) = ((a ∖ {y}) ∪
{y})) | 
| 138 | 137 | eqeq2d 2364 | 
. . . . . . . . . . . . . . . . . . . 20
⊢ (w = y →
(((a ∖
{y}) ∪ {y}) = ((a ∖ {y}) ∪
{w}) ↔ ((a ∖ {y}) ∪ {y}) =
((a ∖
{y}) ∪ {y}))) | 
| 139 | 138 | rspcev 2956 | 
. . . . . . . . . . . . . . . . . . 19
⊢ ((y ∈ ∼
(a ∖
{y}) ∧
((a ∖
{y}) ∪ {y}) = ((a ∖ {y}) ∪
{y})) → ∃w ∈ ∼ (a
∖ {y})((a ∖ {y}) ∪
{y}) = ((a ∖ {y}) ∪ {w})) | 
| 140 | 134, 135,
139 | mp2an 653 | 
. . . . . . . . . . . . . . . . . 18
⊢ ∃w ∈ ∼ (a
∖ {y})((a ∖ {y}) ∪
{y}) = ((a ∖ {y}) ∪ {w}) | 
| 141 |   | compleq 3244 | 
. . . . . . . . . . . . . . . . . . . . 21
⊢ (d = (a ∖ {y}) →
∼ d = ∼ (a ∖ {y})) | 
| 142 |   | uneq1 3412 | 
. . . . . . . . . . . . . . . . . . . . . 22
⊢ (d = (a ∖ {y}) →
(d ∪ {w}) = ((a ∖ {y}) ∪
{w})) | 
| 143 | 142 | eqeq2d 2364 | 
. . . . . . . . . . . . . . . . . . . . 21
⊢ (d = (a ∖ {y}) →
(((a ∖
{y}) ∪ {y}) = (d ∪
{w}) ↔ ((a ∖ {y}) ∪ {y}) =
((a ∖
{y}) ∪ {w}))) | 
| 144 | 141, 143 | rexeqbidv 2821 | 
. . . . . . . . . . . . . . . . . . . 20
⊢ (d = (a ∖ {y}) →
(∃w
∈ ∼ d((a ∖ {y}) ∪
{y}) = (d ∪ {w})
↔ ∃w ∈ ∼
(a ∖
{y})((a
∖ {y})
∪ {y}) = ((a ∖ {y}) ∪ {w}))) | 
| 145 | 144 | rspcev 2956 | 
. . . . . . . . . . . . . . . . . . 19
⊢ (((a ∖ {y}) ∈ n ∧ ∃w ∈ ∼ (a
∖ {y})((a ∖ {y}) ∪
{y}) = ((a ∖ {y}) ∪ {w}))
→ ∃d ∈ n ∃w ∈ ∼ d((a ∖ {y}) ∪
{y}) = (d ∪ {w})) | 
| 146 |   | elsuc 4414 | 
. . . . . . . . . . . . . . . . . . 19
⊢ (((a ∖ {y}) ∪ {y})
∈ (n
+c 1c) ↔ ∃d ∈ n ∃w ∈ ∼ d((a ∖ {y}) ∪
{y}) = (d ∪ {w})) | 
| 147 | 145, 146 | sylibr 203 | 
. . . . . . . . . . . . . . . . . 18
⊢ (((a ∖ {y}) ∈ n ∧ ∃w ∈ ∼ (a
∖ {y})((a ∖ {y}) ∪
{y}) = ((a ∖ {y}) ∪ {w}))
→ ((a ∖ {y}) ∪
{y}) ∈
(n +c
1c)) | 
| 148 | 128, 140,
147 | sylancl 643 | 
. . . . . . . . . . . . . . . . 17
⊢ ((x ≠ y ∧ (∀c∀z((¬ z ∈ c ∧ (c ∪
{z}) ∈
(n +c
1c)) → c ∈ n) ∧ (b ∈ (n
+c 1c) ∧
¬ y ∈
b) ∧
((a ∪ {x}) = (b ∪
{y}) ∧
¬ x ∈
a)) ∧
b = ((a
∖ {y})
∪ {x})) → ((a ∖ {y}) ∪ {y})
∈ (n
+c 1c)) | 
| 149 | 101, 148 | eqeltrrd 2428 | 
. . . . . . . . . . . . . . . 16
⊢ ((x ≠ y ∧ (∀c∀z((¬ z ∈ c ∧ (c ∪
{z}) ∈
(n +c
1c)) → c ∈ n) ∧ (b ∈ (n
+c 1c) ∧
¬ y ∈
b) ∧
((a ∪ {x}) = (b ∪
{y}) ∧
¬ x ∈
a)) ∧
b = ((a
∖ {y})
∪ {x})) → a ∈ (n +c
1c)) | 
| 150 | 83, 149 | mpd3an3 1278 | 
. . . . . . . . . . . . . . 15
⊢ ((x ≠ y ∧ (∀c∀z((¬ z ∈ c ∧ (c ∪
{z}) ∈
(n +c
1c)) → c ∈ n) ∧ (b ∈ (n
+c 1c) ∧
¬ y ∈
b) ∧
((a ∪ {x}) = (b ∪
{y}) ∧
¬ x ∈
a))) → a ∈ (n +c
1c)) | 
| 151 | 150 | ex 423 | 
. . . . . . . . . . . . . 14
⊢ (x ≠ y →
((∀c∀z((¬ z ∈ c ∧ (c ∪
{z}) ∈
(n +c
1c)) → c ∈ n) ∧ (b ∈ (n
+c 1c) ∧
¬ y ∈
b) ∧
((a ∪ {x}) = (b ∪
{y}) ∧
¬ x ∈
a)) → a ∈ (n +c
1c))) | 
| 152 | 78, 151 | pm2.61ine 2593 | 
. . . . . . . . . . . . 13
⊢ ((∀c∀z((¬
z ∈
c ∧
(c ∪ {z}) ∈ (n +c 1c)) →
c ∈
n) ∧
(b ∈
(n +c
1c) ∧ ¬ y ∈ b) ∧ ((a ∪ {x}) =
(b ∪ {y}) ∧ ¬
x ∈
a)) → a ∈ (n +c
1c)) | 
| 153 | 152 | 3expa 1151 | 
. . . . . . . . . . . 12
⊢ (((∀c∀z((¬
z ∈
c ∧
(c ∪ {z}) ∈ (n +c 1c)) →
c ∈
n) ∧
(b ∈
(n +c
1c) ∧ ¬ y ∈ b)) ∧ ((a ∪ {x}) =
(b ∪ {y}) ∧ ¬
x ∈
a)) → a ∈ (n +c
1c)) | 
| 154 | 153 | exp32 588 | 
. . . . . . . . . . 11
⊢ ((∀c∀z((¬
z ∈
c ∧
(c ∪ {z}) ∈ (n +c 1c)) →
c ∈
n) ∧
(b ∈
(n +c
1c) ∧ ¬ y ∈ b)) → ((a
∪ {x}) = (b ∪ {y})
→ (¬ x ∈ a →
a ∈
(n +c
1c)))) | 
| 155 | 63, 154 | sylan2b 461 | 
. . . . . . . . . 10
⊢ ((∀c∀z((¬
z ∈
c ∧
(c ∪ {z}) ∈ (n +c 1c)) →
c ∈
n) ∧
(b ∈
(n +c
1c) ∧ y ∈ ∼ b)) → ((a
∪ {x}) = (b ∪ {y})
→ (¬ x ∈ a →
a ∈
(n +c
1c)))) | 
| 156 | 155 | rexlimdvva 2746 | 
. . . . . . . . 9
⊢ (∀c∀z((¬
z ∈
c ∧
(c ∪ {z}) ∈ (n +c 1c)) →
c ∈
n) → (∃b ∈ (n
+c 1c)∃y ∈ ∼ b(a ∪
{x}) = (b ∪ {y})
→ (¬ x ∈ a →
a ∈
(n +c
1c)))) | 
| 157 | 60, 156 | syl5bi 208 | 
. . . . . . . 8
⊢ (∀c∀z((¬
z ∈
c ∧
(c ∪ {z}) ∈ (n +c 1c)) →
c ∈
n) → ((a ∪ {x})
∈ ((n
+c 1c) +c
1c) → (¬ x ∈ a →
a ∈
(n +c
1c)))) | 
| 158 | 157 | com23 72 | 
. . . . . . 7
⊢ (∀c∀z((¬
z ∈
c ∧
(c ∪ {z}) ∈ (n +c 1c)) →
c ∈
n) → (¬ x ∈ a → ((a
∪ {x}) ∈ ((n
+c 1c) +c
1c) → a ∈ (n
+c 1c)))) | 
| 159 | 158 | imp3a 420 | 
. . . . . 6
⊢ (∀c∀z((¬
z ∈
c ∧
(c ∪ {z}) ∈ (n +c 1c)) →
c ∈
n) → ((¬ x ∈ a ∧ (a ∪ {x})
∈ ((n
+c 1c) +c
1c)) → a ∈ (n
+c 1c))) | 
| 160 | 159 | alrimivv 1632 | 
. . . . 5
⊢ (∀c∀z((¬
z ∈
c ∧
(c ∪ {z}) ∈ (n +c 1c)) →
c ∈
n) → ∀a∀x((¬
x ∈
a ∧
(a ∪ {x}) ∈ ((n +c 1c)
+c 1c)) → a ∈ (n +c
1c))) | 
| 161 | 160 | a1i 10 | 
. . . 4
⊢ (n ∈ Nn → (∀c∀z((¬ z ∈ c ∧ (c ∪
{z}) ∈
(n +c
1c)) → c ∈ n) →
∀a∀x((¬
x ∈
a ∧
(a ∪ {x}) ∈ ((n +c 1c)
+c 1c)) → a ∈ (n +c
1c)))) | 
| 162 | 1, 17, 36, 42, 48, 59, 161 | finds 4412 | 
. . 3
⊢ (M ∈ Nn → ∀a∀x((¬ x ∈ a ∧ (a ∪
{x}) ∈
(M +c
1c)) → a ∈ M)) | 
| 163 |   | nnsucelr.2 | 
. . . . 5
⊢ X ∈
V | 
| 164 |   | eleq1 2413 | 
. . . . . . . 8
⊢ (x = X →
(x ∈
a ↔ X ∈ a)) | 
| 165 | 164 | notbid 285 | 
. . . . . . 7
⊢ (x = X →
(¬ x ∈ a ↔
¬ X ∈
a)) | 
| 166 |   | sneq 3745 | 
. . . . . . . . 9
⊢ (x = X →
{x} = {X}) | 
| 167 | 166 | uneq2d 3419 | 
. . . . . . . 8
⊢ (x = X →
(a ∪ {x}) = (a ∪
{X})) | 
| 168 | 167 | eleq1d 2419 | 
. . . . . . 7
⊢ (x = X →
((a ∪ {x}) ∈ (M +c 1c) ↔
(a ∪ {X}) ∈ (M +c
1c))) | 
| 169 | 165, 168 | anbi12d 691 | 
. . . . . 6
⊢ (x = X →
((¬ x ∈ a ∧ (a ∪
{x}) ∈
(M +c
1c)) ↔ (¬ X
∈ a ∧ (a ∪
{X}) ∈
(M +c
1c)))) | 
| 170 | 169 | imbi1d 308 | 
. . . . 5
⊢ (x = X →
(((¬ x ∈ a ∧ (a ∪
{x}) ∈
(M +c
1c)) → a ∈ M) ↔
((¬ X ∈ a ∧ (a ∪
{X}) ∈
(M +c
1c)) → a ∈ M))) | 
| 171 | 163, 170 | spcv 2946 | 
. . . 4
⊢ (∀x((¬
x ∈
a ∧
(a ∪ {x}) ∈ (M +c 1c)) →
a ∈
M) → ((¬ X ∈ a ∧ (a ∪ {X})
∈ (M
+c 1c)) → a ∈ M)) | 
| 172 | 171 | alimi 1559 | 
. . 3
⊢ (∀a∀x((¬
x ∈
a ∧
(a ∪ {x}) ∈ (M +c 1c)) →
a ∈
M) → ∀a((¬
X ∈
a ∧
(a ∪ {X}) ∈ (M +c 1c)) →
a ∈
M)) | 
| 173 |   | nnsucelr.1 | 
. . . 4
⊢ A ∈
V | 
| 174 |   | eleq2 2414 | 
. . . . . . 7
⊢ (a = A →
(X ∈
a ↔ X ∈ A)) | 
| 175 | 174 | notbid 285 | 
. . . . . 6
⊢ (a = A →
(¬ X ∈ a ↔
¬ X ∈
A)) | 
| 176 |   | uneq1 3412 | 
. . . . . . 7
⊢ (a = A →
(a ∪ {X}) = (A ∪
{X})) | 
| 177 | 176 | eleq1d 2419 | 
. . . . . 6
⊢ (a = A →
((a ∪ {X}) ∈ (M +c 1c) ↔
(A ∪ {X}) ∈ (M +c
1c))) | 
| 178 | 175, 177 | anbi12d 691 | 
. . . . 5
⊢ (a = A →
((¬ X ∈ a ∧ (a ∪
{X}) ∈
(M +c
1c)) ↔ (¬ X
∈ A ∧ (A ∪
{X}) ∈
(M +c
1c)))) | 
| 179 |   | eleq1 2413 | 
. . . . 5
⊢ (a = A →
(a ∈
M ↔ A ∈ M)) | 
| 180 | 178, 179 | imbi12d 311 | 
. . . 4
⊢ (a = A →
(((¬ X ∈ a ∧ (a ∪
{X}) ∈
(M +c
1c)) → a ∈ M) ↔
((¬ X ∈ A ∧ (A ∪
{X}) ∈
(M +c
1c)) → A ∈ M))) | 
| 181 | 173, 180 | spcv 2946 | 
. . 3
⊢ (∀a((¬
X ∈
a ∧
(a ∪ {X}) ∈ (M +c 1c)) →
a ∈
M) → ((¬ X ∈ A ∧ (A ∪ {X})
∈ (M
+c 1c)) → A ∈ M)) | 
| 182 | 162, 172,
181 | 3syl 18 | 
. 2
⊢ (M ∈ Nn → ((¬ X
∈ A ∧ (A ∪
{X}) ∈
(M +c
1c)) → A ∈ M)) | 
| 183 | 182 | imp 418 | 
1
⊢ ((M ∈ Nn ∧ (¬ X ∈ A ∧ (A ∪ {X})
∈ (M
+c 1c))) → A ∈ M) |