| Step | Hyp | Ref
 | Expression | 
| 1 |   | zfregfr 4610 | 
. 2
⊢  E Fr
𝐴 | 
| 2 |   | epel 4327 | 
. . . . . 6
⊢ (𝑎 E 𝑏 ↔ 𝑎 ∈ 𝑏) | 
| 3 |   | epel 4327 | 
. . . . . 6
⊢ (𝑏 E 𝑐 ↔ 𝑏 ∈ 𝑐) | 
| 4 | 2, 3 | anbi12i 460 | 
. . . . 5
⊢ ((𝑎 E 𝑏 ∧ 𝑏 E 𝑐) ↔ (𝑎 ∈ 𝑏 ∧ 𝑏 ∈ 𝑐)) | 
| 5 |   | simpr 110 | 
. . . . . 6
⊢ (((𝑎 ∈ 𝐴 ∧ 𝑏 ∈ 𝐴 ∧ 𝑐 ∈ 𝐴) ∧ (𝑎 ∈ 𝑏 ∧ 𝑏 ∈ 𝑐)) → (𝑎 ∈ 𝑏 ∧ 𝑏 ∈ 𝑐)) | 
| 6 |   | elirr 4577 | 
. . . . . . . 8
⊢  ¬
{∅} ∈ {∅} | 
| 7 |   | simprr 531 | 
. . . . . . . . . 10
⊢ (((𝑎 ∈ 𝐴 ∧ 𝑏 ∈ 𝐴 ∧ 𝑐 ∈ 𝐴) ∧ (𝑎 ∈ 𝑏 ∧ 𝑏 ∈ 𝑐)) → 𝑏 ∈ 𝑐) | 
| 8 |   | noel 3454 | 
. . . . . . . . . . . . 13
⊢  ¬
𝑎 ∈
∅ | 
| 9 |   | eleq2 2260 | 
. . . . . . . . . . . . 13
⊢ (𝑏 = ∅ → (𝑎 ∈ 𝑏 ↔ 𝑎 ∈ ∅)) | 
| 10 | 8, 9 | mtbiri 676 | 
. . . . . . . . . . . 12
⊢ (𝑏 = ∅ → ¬ 𝑎 ∈ 𝑏) | 
| 11 |   | simprl 529 | 
. . . . . . . . . . . 12
⊢ (((𝑎 ∈ 𝐴 ∧ 𝑏 ∈ 𝐴 ∧ 𝑐 ∈ 𝐴) ∧ (𝑎 ∈ 𝑏 ∧ 𝑏 ∈ 𝑐)) → 𝑎 ∈ 𝑏) | 
| 12 | 10, 11 | nsyl3 627 | 
. . . . . . . . . . 11
⊢ (((𝑎 ∈ 𝐴 ∧ 𝑏 ∈ 𝐴 ∧ 𝑐 ∈ 𝐴) ∧ (𝑎 ∈ 𝑏 ∧ 𝑏 ∈ 𝑐)) → ¬ 𝑏 = ∅) | 
| 13 |   | elrabi 2917 | 
. . . . . . . . . . . . . . . 16
⊢ (𝑏 ∈ {𝑥 ∈ {∅, {∅}} ∣ (𝑥 = {∅} ∨ (𝑥 = ∅ ∧ 𝜑))} → 𝑏 ∈ {∅,
{∅}}) | 
| 14 |   | reg3exmidlemwe.a | 
. . . . . . . . . . . . . . . 16
⊢ 𝐴 = {𝑥 ∈ {∅, {∅}} ∣ (𝑥 = {∅} ∨ (𝑥 = ∅ ∧ 𝜑))} | 
| 15 | 13, 14 | eleq2s 2291 | 
. . . . . . . . . . . . . . 15
⊢ (𝑏 ∈ 𝐴 → 𝑏 ∈ {∅,
{∅}}) | 
| 16 |   | elpri 3645 | 
. . . . . . . . . . . . . . 15
⊢ (𝑏 ∈ {∅, {∅}}
→ (𝑏 = ∅ ∨
𝑏 =
{∅})) | 
| 17 | 15, 16 | syl 14 | 
. . . . . . . . . . . . . 14
⊢ (𝑏 ∈ 𝐴 → (𝑏 = ∅ ∨ 𝑏 = {∅})) | 
| 18 | 17 | orcomd 730 | 
. . . . . . . . . . . . 13
⊢ (𝑏 ∈ 𝐴 → (𝑏 = {∅} ∨ 𝑏 = ∅)) | 
| 19 | 18 | 3ad2ant2 1021 | 
. . . . . . . . . . . 12
⊢ ((𝑎 ∈ 𝐴 ∧ 𝑏 ∈ 𝐴 ∧ 𝑐 ∈ 𝐴) → (𝑏 = {∅} ∨ 𝑏 = ∅)) | 
| 20 | 19 | adantr 276 | 
. . . . . . . . . . 11
⊢ (((𝑎 ∈ 𝐴 ∧ 𝑏 ∈ 𝐴 ∧ 𝑐 ∈ 𝐴) ∧ (𝑎 ∈ 𝑏 ∧ 𝑏 ∈ 𝑐)) → (𝑏 = {∅} ∨ 𝑏 = ∅)) | 
| 21 | 12, 20 | ecased 1360 | 
. . . . . . . . . 10
⊢ (((𝑎 ∈ 𝐴 ∧ 𝑏 ∈ 𝐴 ∧ 𝑐 ∈ 𝐴) ∧ (𝑎 ∈ 𝑏 ∧ 𝑏 ∈ 𝑐)) → 𝑏 = {∅}) | 
| 22 |   | noel 3454 | 
. . . . . . . . . . . . 13
⊢  ¬
𝑏 ∈
∅ | 
| 23 |   | eleq2 2260 | 
. . . . . . . . . . . . 13
⊢ (𝑐 = ∅ → (𝑏 ∈ 𝑐 ↔ 𝑏 ∈ ∅)) | 
| 24 | 22, 23 | mtbiri 676 | 
. . . . . . . . . . . 12
⊢ (𝑐 = ∅ → ¬ 𝑏 ∈ 𝑐) | 
| 25 | 24, 7 | nsyl3 627 | 
. . . . . . . . . . 11
⊢ (((𝑎 ∈ 𝐴 ∧ 𝑏 ∈ 𝐴 ∧ 𝑐 ∈ 𝐴) ∧ (𝑎 ∈ 𝑏 ∧ 𝑏 ∈ 𝑐)) → ¬ 𝑐 = ∅) | 
| 26 |   | elrabi 2917 | 
. . . . . . . . . . . . . . . 16
⊢ (𝑐 ∈ {𝑥 ∈ {∅, {∅}} ∣ (𝑥 = {∅} ∨ (𝑥 = ∅ ∧ 𝜑))} → 𝑐 ∈ {∅,
{∅}}) | 
| 27 | 26, 14 | eleq2s 2291 | 
. . . . . . . . . . . . . . 15
⊢ (𝑐 ∈ 𝐴 → 𝑐 ∈ {∅,
{∅}}) | 
| 28 |   | vex 2766 | 
. . . . . . . . . . . . . . . 16
⊢ 𝑐 ∈ V | 
| 29 | 28 | elpr 3643 | 
. . . . . . . . . . . . . . 15
⊢ (𝑐 ∈ {∅, {∅}}
↔ (𝑐 = ∅ ∨
𝑐 =
{∅})) | 
| 30 | 27, 29 | sylib 122 | 
. . . . . . . . . . . . . 14
⊢ (𝑐 ∈ 𝐴 → (𝑐 = ∅ ∨ 𝑐 = {∅})) | 
| 31 | 30 | orcomd 730 | 
. . . . . . . . . . . . 13
⊢ (𝑐 ∈ 𝐴 → (𝑐 = {∅} ∨ 𝑐 = ∅)) | 
| 32 | 31 | 3ad2ant3 1022 | 
. . . . . . . . . . . 12
⊢ ((𝑎 ∈ 𝐴 ∧ 𝑏 ∈ 𝐴 ∧ 𝑐 ∈ 𝐴) → (𝑐 = {∅} ∨ 𝑐 = ∅)) | 
| 33 | 32 | adantr 276 | 
. . . . . . . . . . 11
⊢ (((𝑎 ∈ 𝐴 ∧ 𝑏 ∈ 𝐴 ∧ 𝑐 ∈ 𝐴) ∧ (𝑎 ∈ 𝑏 ∧ 𝑏 ∈ 𝑐)) → (𝑐 = {∅} ∨ 𝑐 = ∅)) | 
| 34 | 25, 33 | ecased 1360 | 
. . . . . . . . . 10
⊢ (((𝑎 ∈ 𝐴 ∧ 𝑏 ∈ 𝐴 ∧ 𝑐 ∈ 𝐴) ∧ (𝑎 ∈ 𝑏 ∧ 𝑏 ∈ 𝑐)) → 𝑐 = {∅}) | 
| 35 | 7, 21, 34 | 3eltr3d 2279 | 
. . . . . . . . 9
⊢ (((𝑎 ∈ 𝐴 ∧ 𝑏 ∈ 𝐴 ∧ 𝑐 ∈ 𝐴) ∧ (𝑎 ∈ 𝑏 ∧ 𝑏 ∈ 𝑐)) → {∅} ∈
{∅}) | 
| 36 | 35 | ex 115 | 
. . . . . . . 8
⊢ ((𝑎 ∈ 𝐴 ∧ 𝑏 ∈ 𝐴 ∧ 𝑐 ∈ 𝐴) → ((𝑎 ∈ 𝑏 ∧ 𝑏 ∈ 𝑐) → {∅} ∈
{∅})) | 
| 37 | 6, 36 | mtoi 665 | 
. . . . . . 7
⊢ ((𝑎 ∈ 𝐴 ∧ 𝑏 ∈ 𝐴 ∧ 𝑐 ∈ 𝐴) → ¬ (𝑎 ∈ 𝑏 ∧ 𝑏 ∈ 𝑐)) | 
| 38 | 37 | adantr 276 | 
. . . . . 6
⊢ (((𝑎 ∈ 𝐴 ∧ 𝑏 ∈ 𝐴 ∧ 𝑐 ∈ 𝐴) ∧ (𝑎 ∈ 𝑏 ∧ 𝑏 ∈ 𝑐)) → ¬ (𝑎 ∈ 𝑏 ∧ 𝑏 ∈ 𝑐)) | 
| 39 | 5, 38 | pm2.21dd 621 | 
. . . . 5
⊢ (((𝑎 ∈ 𝐴 ∧ 𝑏 ∈ 𝐴 ∧ 𝑐 ∈ 𝐴) ∧ (𝑎 ∈ 𝑏 ∧ 𝑏 ∈ 𝑐)) → 𝑎 E 𝑐) | 
| 40 | 4, 39 | sylan2b 287 | 
. . . 4
⊢ (((𝑎 ∈ 𝐴 ∧ 𝑏 ∈ 𝐴 ∧ 𝑐 ∈ 𝐴) ∧ (𝑎 E 𝑏 ∧ 𝑏 E 𝑐)) → 𝑎 E 𝑐) | 
| 41 | 40 | ex 115 | 
. . 3
⊢ ((𝑎 ∈ 𝐴 ∧ 𝑏 ∈ 𝐴 ∧ 𝑐 ∈ 𝐴) → ((𝑎 E 𝑏 ∧ 𝑏 E 𝑐) → 𝑎 E 𝑐)) | 
| 42 | 41 | rgen3 2584 | 
. 2
⊢
∀𝑎 ∈
𝐴 ∀𝑏 ∈ 𝐴 ∀𝑐 ∈ 𝐴 ((𝑎 E 𝑏 ∧ 𝑏 E 𝑐) → 𝑎 E 𝑐) | 
| 43 |   | df-wetr 4369 | 
. 2
⊢ ( E We
𝐴 ↔ ( E Fr 𝐴 ∧ ∀𝑎 ∈ 𝐴 ∀𝑏 ∈ 𝐴 ∀𝑐 ∈ 𝐴 ((𝑎 E 𝑏 ∧ 𝑏 E 𝑐) → 𝑎 E 𝑐))) | 
| 44 | 1, 42, 43 | mpbir2an 944 | 
1
⊢  E We
𝐴 |