Proof of Theorem exmidpw
| Step | Hyp | Ref
 | Expression | 
| 1 |   | df1o2 6487 | 
. . . . 5
⊢
1o = {∅} | 
| 2 |   | p0ex 4221 | 
. . . . 5
⊢ {∅}
∈ V | 
| 3 | 1, 2 | eqeltri 2269 | 
. . . 4
⊢
1o ∈ V | 
| 4 | 3 | pwex 4216 | 
. . 3
⊢ 𝒫
1o ∈ V | 
| 5 |   | exmid01 4231 | 
. . . . . . . . 9
⊢
(EXMID ↔ ∀𝑥(𝑥 ⊆ {∅} → (𝑥 = ∅ ∨ 𝑥 = {∅}))) | 
| 6 | 5 | biimpi 120 | 
. . . . . . . 8
⊢
(EXMID → ∀𝑥(𝑥 ⊆ {∅} → (𝑥 = ∅ ∨ 𝑥 = {∅}))) | 
| 7 | 6 | 19.21bi 1572 | 
. . . . . . 7
⊢
(EXMID → (𝑥 ⊆ {∅} → (𝑥 = ∅ ∨ 𝑥 = {∅}))) | 
| 8 | 1 | pweqi 3609 | 
. . . . . . . . 9
⊢ 𝒫
1o = 𝒫 {∅} | 
| 9 | 8 | eleq2i 2263 | 
. . . . . . . 8
⊢ (𝑥 ∈ 𝒫 1o
↔ 𝑥 ∈ 𝒫
{∅}) | 
| 10 |   | velpw 3612 | 
. . . . . . . 8
⊢ (𝑥 ∈ 𝒫 {∅}
↔ 𝑥 ⊆
{∅}) | 
| 11 | 9, 10 | bitri 184 | 
. . . . . . 7
⊢ (𝑥 ∈ 𝒫 1o
↔ 𝑥 ⊆
{∅}) | 
| 12 |   | vex 2766 | 
. . . . . . . 8
⊢ 𝑥 ∈ V | 
| 13 | 12 | elpr 3643 | 
. . . . . . 7
⊢ (𝑥 ∈ {∅, {∅}}
↔ (𝑥 = ∅ ∨
𝑥 =
{∅})) | 
| 14 | 7, 11, 13 | 3imtr4g 205 | 
. . . . . 6
⊢
(EXMID → (𝑥 ∈ 𝒫 1o → 𝑥 ∈ {∅,
{∅}})) | 
| 15 | 14 | ssrdv 3189 | 
. . . . 5
⊢
(EXMID → 𝒫 1o ⊆ {∅,
{∅}}) | 
| 16 |   | pwpw0ss 3834 | 
. . . . . . 7
⊢ {∅,
{∅}} ⊆ 𝒫 {∅} | 
| 17 | 16, 8 | sseqtrri 3218 | 
. . . . . 6
⊢ {∅,
{∅}} ⊆ 𝒫 1o | 
| 18 | 17 | a1i 9 | 
. . . . 5
⊢
(EXMID → {∅, {∅}} ⊆ 𝒫
1o) | 
| 19 | 15, 18 | eqssd 3200 | 
. . . 4
⊢
(EXMID → 𝒫 1o = {∅,
{∅}}) | 
| 20 |   | df2o2 6489 | 
. . . 4
⊢
2o = {∅, {∅}} | 
| 21 | 19, 20 | eqtr4di 2247 | 
. . 3
⊢
(EXMID → 𝒫 1o =
2o) | 
| 22 |   | eqeng 6825 | 
. . 3
⊢
(𝒫 1o ∈ V → (𝒫 1o =
2o → 𝒫 1o ≈
2o)) | 
| 23 | 4, 21, 22 | mpsyl 65 | 
. 2
⊢
(EXMID → 𝒫 1o ≈
2o) | 
| 24 |   | 0nep0 4198 | 
. . . . . . . 8
⊢ ∅
≠ {∅} | 
| 25 |   | 0ex 4160 | 
. . . . . . . . . . 11
⊢ ∅
∈ V | 
| 26 | 25, 2 | prss 3778 | 
. . . . . . . . . 10
⊢ ((∅
∈ 𝒫 1o ∧ {∅} ∈ 𝒫 1o)
↔ {∅, {∅}} ⊆ 𝒫 1o) | 
| 27 | 17, 26 | mpbir 146 | 
. . . . . . . . 9
⊢ (∅
∈ 𝒫 1o ∧ {∅} ∈ 𝒫
1o) | 
| 28 |   | en2eqpr 6968 | 
. . . . . . . . . 10
⊢
((𝒫 1o ≈ 2o ∧ ∅ ∈
𝒫 1o ∧ {∅} ∈ 𝒫 1o) →
(∅ ≠ {∅} → 𝒫 1o = {∅,
{∅}})) | 
| 29 | 28 | 3expb 1206 | 
. . . . . . . . 9
⊢
((𝒫 1o ≈ 2o ∧ (∅ ∈
𝒫 1o ∧ {∅} ∈ 𝒫 1o)) →
(∅ ≠ {∅} → 𝒫 1o = {∅,
{∅}})) | 
| 30 | 27, 29 | mpan2 425 | 
. . . . . . . 8
⊢
(𝒫 1o ≈ 2o → (∅ ≠
{∅} → 𝒫 1o = {∅,
{∅}})) | 
| 31 | 24, 30 | mpi 15 | 
. . . . . . 7
⊢
(𝒫 1o ≈ 2o → 𝒫
1o = {∅, {∅}}) | 
| 32 | 31 | eleq2d 2266 | 
. . . . . 6
⊢
(𝒫 1o ≈ 2o → (𝑥 ∈ 𝒫 1o
↔ 𝑥 ∈ {∅,
{∅}})) | 
| 33 | 32, 11, 13 | 3bitr3g 222 | 
. . . . 5
⊢
(𝒫 1o ≈ 2o → (𝑥 ⊆ {∅} ↔ (𝑥 = ∅ ∨ 𝑥 = {∅}))) | 
| 34 | 33 | biimpd 144 | 
. . . 4
⊢
(𝒫 1o ≈ 2o → (𝑥 ⊆ {∅} → (𝑥 = ∅ ∨ 𝑥 = {∅}))) | 
| 35 | 34 | alrimiv 1888 | 
. . 3
⊢
(𝒫 1o ≈ 2o → ∀𝑥(𝑥 ⊆ {∅} → (𝑥 = ∅ ∨ 𝑥 = {∅}))) | 
| 36 | 35, 5 | sylibr 134 | 
. 2
⊢
(𝒫 1o ≈ 2o →
EXMID) | 
| 37 | 23, 36 | impbii 126 | 
1
⊢
(EXMID ↔ 𝒫 1o ≈
2o) |