| Step | Hyp | Ref
 | Expression | 
| 1 |   | onsucelsucexmidlem 4565 | 
. . . 4
⊢ {𝑠 ∈ {∅, {∅}}
∣ (𝑠 = ∅ ∨
𝜑)} ∈
On | 
| 2 |   | pp0ex 4222 | 
. . . . 5
⊢ {∅,
{∅}} ∈ V | 
| 3 | 2 | rabex 4177 | 
. . . 4
⊢ {𝑠 ∈ {∅, {∅}}
∣ (𝑠 = {∅} ∨
𝜑)} ∈ V | 
| 4 |   | prexg 4244 | 
. . . 4
⊢ (({𝑠 ∈ {∅, {∅}}
∣ (𝑠 = ∅ ∨
𝜑)} ∈ On ∧ {𝑠 ∈ {∅, {∅}}
∣ (𝑠 = {∅} ∨
𝜑)} ∈ V) → {{𝑠 ∈ {∅, {∅}}
∣ (𝑠 = ∅ ∨
𝜑)}, {𝑠 ∈ {∅, {∅}} ∣ (𝑠 = {∅} ∨ 𝜑)}} ∈ V) | 
| 5 | 1, 3, 4 | mp2an 426 | 
. . 3
⊢ {{𝑠 ∈ {∅, {∅}}
∣ (𝑠 = ∅ ∨
𝜑)}, {𝑠 ∈ {∅, {∅}} ∣ (𝑠 = {∅} ∨ 𝜑)}} ∈ V | 
| 6 |   | raleq 2693 | 
. . . 4
⊢ (𝑥 = {{𝑠 ∈ {∅, {∅}} ∣ (𝑠 = ∅ ∨ 𝜑)}, {𝑠 ∈ {∅, {∅}} ∣ (𝑠 = {∅} ∨ 𝜑)}} → (∀𝑧 ∈ 𝑥 ∀𝑤 ∈ 𝑧 ∃!𝑣 ∈ 𝑧 ∃𝑢 ∈ 𝑦 (𝑧 ∈ 𝑢 ∧ 𝑣 ∈ 𝑢) ↔ ∀𝑧 ∈ {{𝑠 ∈ {∅, {∅}} ∣ (𝑠 = ∅ ∨ 𝜑)}, {𝑠 ∈ {∅, {∅}} ∣ (𝑠 = {∅} ∨ 𝜑)}}∀𝑤 ∈ 𝑧 ∃!𝑣 ∈ 𝑧 ∃𝑢 ∈ 𝑦 (𝑧 ∈ 𝑢 ∧ 𝑣 ∈ 𝑢))) | 
| 7 | 6 | exbidv 1839 | 
. . 3
⊢ (𝑥 = {{𝑠 ∈ {∅, {∅}} ∣ (𝑠 = ∅ ∨ 𝜑)}, {𝑠 ∈ {∅, {∅}} ∣ (𝑠 = {∅} ∨ 𝜑)}} → (∃𝑦∀𝑧 ∈ 𝑥 ∀𝑤 ∈ 𝑧 ∃!𝑣 ∈ 𝑧 ∃𝑢 ∈ 𝑦 (𝑧 ∈ 𝑢 ∧ 𝑣 ∈ 𝑢) ↔ ∃𝑦∀𝑧 ∈ {{𝑠 ∈ {∅, {∅}} ∣ (𝑠 = ∅ ∨ 𝜑)}, {𝑠 ∈ {∅, {∅}} ∣ (𝑠 = {∅} ∨ 𝜑)}}∀𝑤 ∈ 𝑧 ∃!𝑣 ∈ 𝑧 ∃𝑢 ∈ 𝑦 (𝑧 ∈ 𝑢 ∧ 𝑣 ∈ 𝑢))) | 
| 8 |   | acexmidlemv.choice | 
. . 3
⊢
∃𝑦∀𝑧 ∈ 𝑥 ∀𝑤 ∈ 𝑧 ∃!𝑣 ∈ 𝑧 ∃𝑢 ∈ 𝑦 (𝑧 ∈ 𝑢 ∧ 𝑣 ∈ 𝑢) | 
| 9 | 5, 7, 8 | vtocl 2818 | 
. 2
⊢
∃𝑦∀𝑧 ∈ {{𝑠 ∈ {∅, {∅}} ∣ (𝑠 = ∅ ∨ 𝜑)}, {𝑠 ∈ {∅, {∅}} ∣ (𝑠 = {∅} ∨ 𝜑)}}∀𝑤 ∈ 𝑧 ∃!𝑣 ∈ 𝑧 ∃𝑢 ∈ 𝑦 (𝑧 ∈ 𝑢 ∧ 𝑣 ∈ 𝑢) | 
| 10 |   | eqeq1 2203 | 
. . . . . 6
⊢ (𝑠 = 𝑡 → (𝑠 = ∅ ↔ 𝑡 = ∅)) | 
| 11 | 10 | orbi1d 792 | 
. . . . 5
⊢ (𝑠 = 𝑡 → ((𝑠 = ∅ ∨ 𝜑) ↔ (𝑡 = ∅ ∨ 𝜑))) | 
| 12 | 11 | cbvrabv 2762 | 
. . . 4
⊢ {𝑠 ∈ {∅, {∅}}
∣ (𝑠 = ∅ ∨
𝜑)} = {𝑡 ∈ {∅, {∅}} ∣ (𝑡 = ∅ ∨ 𝜑)} | 
| 13 |   | eqeq1 2203 | 
. . . . . 6
⊢ (𝑠 = 𝑡 → (𝑠 = {∅} ↔ 𝑡 = {∅})) | 
| 14 | 13 | orbi1d 792 | 
. . . . 5
⊢ (𝑠 = 𝑡 → ((𝑠 = {∅} ∨ 𝜑) ↔ (𝑡 = {∅} ∨ 𝜑))) | 
| 15 | 14 | cbvrabv 2762 | 
. . . 4
⊢ {𝑠 ∈ {∅, {∅}}
∣ (𝑠 = {∅} ∨
𝜑)} = {𝑡 ∈ {∅, {∅}} ∣ (𝑡 = {∅} ∨ 𝜑)} | 
| 16 |   | eqid 2196 | 
. . . 4
⊢ {{𝑠 ∈ {∅, {∅}}
∣ (𝑠 = ∅ ∨
𝜑)}, {𝑠 ∈ {∅, {∅}} ∣ (𝑠 = {∅} ∨ 𝜑)}} = {{𝑠 ∈ {∅, {∅}} ∣ (𝑠 = ∅ ∨ 𝜑)}, {𝑠 ∈ {∅, {∅}} ∣ (𝑠 = {∅} ∨ 𝜑)}} | 
| 17 | 12, 15, 16 | acexmidlem2 5919 | 
. . 3
⊢
(∀𝑧 ∈
{{𝑠 ∈ {∅,
{∅}} ∣ (𝑠 =
∅ ∨ 𝜑)}, {𝑠 ∈ {∅, {∅}}
∣ (𝑠 = {∅} ∨
𝜑)}}∀𝑤 ∈ 𝑧 ∃!𝑣 ∈ 𝑧 ∃𝑢 ∈ 𝑦 (𝑧 ∈ 𝑢 ∧ 𝑣 ∈ 𝑢) → (𝜑 ∨ ¬ 𝜑)) | 
| 18 | 17 | exlimiv 1612 | 
. 2
⊢
(∃𝑦∀𝑧 ∈ {{𝑠 ∈ {∅, {∅}} ∣ (𝑠 = ∅ ∨ 𝜑)}, {𝑠 ∈ {∅, {∅}} ∣ (𝑠 = {∅} ∨ 𝜑)}}∀𝑤 ∈ 𝑧 ∃!𝑣 ∈ 𝑧 ∃𝑢 ∈ 𝑦 (𝑧 ∈ 𝑢 ∧ 𝑣 ∈ 𝑢) → (𝜑 ∨ ¬ 𝜑)) | 
| 19 | 9, 18 | ax-mp 5 | 
1
⊢ (𝜑 ∨ ¬ 𝜑) |