| Step | Hyp | Ref
 | Expression | 
| 1 |   | pw1fnf1o 5856 | 
. . . . 5
⊢  Pw1Fn :1c–1-1-onto→℘1c | 
| 2 |   | f1of1 5287 | 
. . . . 5
⊢ ( Pw1Fn :1c–1-1-onto→℘1c → Pw1Fn :1c–1-1→℘1c) | 
| 3 | 1, 2 | ax-mp 5 | 
. . . 4
⊢  Pw1Fn :1c–1-1→℘1c | 
| 4 |   | pw1ss1c 4159 | 
. . . 4
⊢ ℘1℘A ⊆ 1c | 
| 5 |   | f1ores 5301 | 
. . . 4
⊢ (( Pw1Fn :1c–1-1→℘1c ∧ ℘1℘A ⊆ 1c) → ( Pw1Fn ↾ ℘1℘A):℘1℘A–1-1-onto→(
Pw1Fn “ ℘1℘A)) | 
| 6 | 3, 4, 5 | mp2an 653 | 
. . 3
⊢ ( Pw1Fn ↾ ℘1℘A):℘1℘A–1-1-onto→(
Pw1Fn “ ℘1℘A) | 
| 7 |   | df-ima 4728 | 
. . . . 5
⊢ ( Pw1Fn “ ℘1℘A) =
{x ∣
∃y ∈ ℘1
℘Ay Pw1Fn x} | 
| 8 |   | vex 2863 | 
. . . . . . . . 9
⊢ x ∈
V | 
| 9 | 8 | elpw 3729 | 
. . . . . . . 8
⊢ (x ∈ ℘℘1A ↔ x ⊆ ℘1A) | 
| 10 | 8 | sspw1 4336 | 
. . . . . . . 8
⊢ (x ⊆ ℘1A ↔ ∃z(z ⊆ A ∧ x = ℘1z)) | 
| 11 |   | df-rex 2621 | 
. . . . . . . . 9
⊢ (∃z ∈ ℘ Ax = ℘1z ↔ ∃z(z ∈ ℘A ∧ x = ℘1z)) | 
| 12 |   | df-pw 3725 | 
. . . . . . . . . . . 12
⊢ ℘A =
{z ∣
z ⊆
A} | 
| 13 | 12 | eqabri 2461 | 
. . . . . . . . . . 11
⊢ (z ∈ ℘A ↔
z ⊆
A) | 
| 14 | 13 | anbi1i 676 | 
. . . . . . . . . 10
⊢ ((z ∈ ℘A ∧ x = ℘1z) ↔ (z
⊆ A
∧ x =
℘1z)) | 
| 15 | 14 | exbii 1582 | 
. . . . . . . . 9
⊢ (∃z(z ∈ ℘A ∧ x = ℘1z) ↔ ∃z(z ⊆ A ∧ x = ℘1z)) | 
| 16 | 11, 15 | bitr2i 241 | 
. . . . . . . 8
⊢ (∃z(z ⊆ A ∧ x = ℘1z) ↔ ∃z ∈ ℘ Ax = ℘1z) | 
| 17 | 9, 10, 16 | 3bitri 262 | 
. . . . . . 7
⊢ (x ∈ ℘℘1A ↔ ∃z ∈ ℘ Ax = ℘1z) | 
| 18 |   | df-rex 2621 | 
. . . . . . . 8
⊢ (∃y ∈ ℘1
℘Ay Pw1Fn x ↔ ∃y(y ∈ ℘1℘A ∧ y Pw1Fn x)) | 
| 19 |   | elpw1 4145 | 
. . . . . . . . . . 11
⊢ (y ∈ ℘1℘A ↔
∃z ∈ ℘ Ay = {z}) | 
| 20 | 19 | anbi1i 676 | 
. . . . . . . . . 10
⊢ ((y ∈ ℘1℘A ∧ y Pw1Fn x) ↔
(∃z
∈ ℘
Ay =
{z} ∧
y Pw1Fn
x)) | 
| 21 |   | r19.41v 2765 | 
. . . . . . . . . 10
⊢ (∃z ∈ ℘ A(y = {z} ∧ y Pw1Fn x) ↔ (∃z ∈ ℘ Ay = {z} ∧ y Pw1Fn x)) | 
| 22 | 20, 21 | bitr4i 243 | 
. . . . . . . . 9
⊢ ((y ∈ ℘1℘A ∧ y Pw1Fn x) ↔
∃z ∈ ℘ A(y = {z} ∧ y Pw1Fn x)) | 
| 23 | 22 | exbii 1582 | 
. . . . . . . 8
⊢ (∃y(y ∈ ℘1℘A ∧ y Pw1Fn x) ↔
∃y∃z ∈ ℘ A(y = {z} ∧ y Pw1Fn x)) | 
| 24 |   | rexcom4 2879 | 
. . . . . . . . 9
⊢ (∃z ∈ ℘ A∃y(y = {z} ∧ y Pw1Fn x) ↔ ∃y∃z ∈ ℘ A(y = {z} ∧ y Pw1Fn x)) | 
| 25 |   | snex 4112 | 
. . . . . . . . . . . 12
⊢ {z} ∈
V | 
| 26 |   | breq1 4643 | 
. . . . . . . . . . . 12
⊢ (y = {z} →
(y Pw1Fn
x ↔ {z} Pw1Fn x)) | 
| 27 | 25, 26 | ceqsexv 2895 | 
. . . . . . . . . . 11
⊢ (∃y(y = {z} ∧ y Pw1Fn x) ↔
{z} Pw1Fn
x) | 
| 28 |   | vex 2863 | 
. . . . . . . . . . . 12
⊢ z ∈
V | 
| 29 | 28 | brpw1fn 5855 | 
. . . . . . . . . . 11
⊢ ({z} Pw1Fn x ↔ x =
℘1z) | 
| 30 | 27, 29 | bitri 240 | 
. . . . . . . . . 10
⊢ (∃y(y = {z} ∧ y Pw1Fn x) ↔
x = ℘1z) | 
| 31 | 30 | rexbii 2640 | 
. . . . . . . . 9
⊢ (∃z ∈ ℘ A∃y(y = {z} ∧ y Pw1Fn x) ↔ ∃z ∈ ℘ Ax = ℘1z) | 
| 32 | 24, 31 | bitr3i 242 | 
. . . . . . . 8
⊢ (∃y∃z ∈ ℘ A(y = {z} ∧ y Pw1Fn x) ↔ ∃z ∈ ℘ Ax = ℘1z) | 
| 33 | 18, 23, 32 | 3bitri 262 | 
. . . . . . 7
⊢ (∃y ∈ ℘1
℘Ay Pw1Fn x ↔ ∃z ∈ ℘ Ax = ℘1z) | 
| 34 | 17, 33 | bitr4i 243 | 
. . . . . 6
⊢ (x ∈ ℘℘1A ↔ ∃y ∈ ℘1
℘Ay Pw1Fn x) | 
| 35 | 34 | eqabi 2465 | 
. . . . 5
⊢ ℘℘1A = {x ∣ ∃y ∈ ℘1 ℘Ay Pw1Fn x} | 
| 36 | 7, 35 | eqtr4i 2376 | 
. . . 4
⊢ ( Pw1Fn “ ℘1℘A) = ℘℘1A | 
| 37 |   | f1oeq3 5284 | 
. . . 4
⊢ (( Pw1Fn “ ℘1℘A) = ℘℘1A → (( Pw1Fn ↾ ℘1℘A):℘1℘A–1-1-onto→(
Pw1Fn “ ℘1℘A) ↔ (
Pw1Fn ↾ ℘1℘A):℘1℘A–1-1-onto→℘℘1A)) | 
| 38 | 36, 37 | ax-mp 5 | 
. . 3
⊢ (( Pw1Fn ↾ ℘1℘A):℘1℘A–1-1-onto→(
Pw1Fn “ ℘1℘A) ↔ (
Pw1Fn ↾ ℘1℘A):℘1℘A–1-1-onto→℘℘1A) | 
| 39 | 6, 38 | mpbi 199 | 
. 2
⊢ ( Pw1Fn ↾ ℘1℘A):℘1℘A–1-1-onto→℘℘1A | 
| 40 |   | pw1fnex 5853 | 
. . . 4
⊢  Pw1Fn ∈
V | 
| 41 |   | enpw1pw.1 | 
. . . . . 6
⊢ A ∈
V | 
| 42 | 41 | pwex 4330 | 
. . . . 5
⊢ ℘A ∈ V | 
| 43 | 42 | pw1ex 4304 | 
. . . 4
⊢ ℘1℘A ∈ V | 
| 44 | 40, 43 | resex 5118 | 
. . 3
⊢ ( Pw1Fn ↾ ℘1℘A) ∈ V | 
| 45 | 44 | f1oen 6034 | 
. 2
⊢ (( Pw1Fn ↾ ℘1℘A):℘1℘A–1-1-onto→℘℘1A → ℘1℘A ≈
℘℘1A) | 
| 46 | 39, 45 | ax-mp 5 | 
1
⊢ ℘1℘A ≈
℘℘1A |