| Step | Hyp | Ref | Expression | 
|---|
| 1 |  | n0snor2el 4833 | . 2
⊢ (𝐴 ≠ ∅ →
(∃𝑥 ∈ 𝐴 ∃𝑦 ∈ 𝐴 𝑥 ≠ 𝑦 ∨ ∃𝑧 𝐴 = {𝑧})) | 
| 2 |  | nfiu1 5027 | . . . . . 6
⊢
Ⅎ𝑥∪ 𝑥 ∈ 𝐴 {〈𝑥, 𝐵〉} | 
| 3 | 2 | nfeq1 2921 | . . . . 5
⊢
Ⅎ𝑥∪ 𝑥 ∈ 𝐴 {〈𝑥, 𝐵〉} = 〈𝐶, 𝐷〉 | 
| 4 |  | nfv 1914 | . . . . 5
⊢
Ⅎ𝑥∃𝑧 𝐴 = {𝑧} | 
| 5 | 3, 4 | nfim 1896 | . . . 4
⊢
Ⅎ𝑥(∪ 𝑥 ∈ 𝐴 {〈𝑥, 𝐵〉} = 〈𝐶, 𝐷〉 → ∃𝑧 𝐴 = {𝑧}) | 
| 6 |  | ssiun2 5047 | . . . . . . 7
⊢ (𝑥 ∈ 𝐴 → {〈𝑥, 𝐵〉} ⊆ ∪ 𝑥 ∈ 𝐴 {〈𝑥, 𝐵〉}) | 
| 7 |  | nfcv 2905 | . . . . . . . 8
⊢
Ⅎ𝑥𝑦 | 
| 8 |  | nfcsb1v 3923 | . . . . . . . . . . 11
⊢
Ⅎ𝑥⦋𝑦 / 𝑥⦌𝐵 | 
| 9 | 7, 8 | nfop 4889 | . . . . . . . . . 10
⊢
Ⅎ𝑥〈𝑦, ⦋𝑦 / 𝑥⦌𝐵〉 | 
| 10 | 9 | nfsn 4707 | . . . . . . . . 9
⊢
Ⅎ𝑥{〈𝑦, ⦋𝑦 / 𝑥⦌𝐵〉} | 
| 11 | 10, 2 | nfss 3976 | . . . . . . . 8
⊢
Ⅎ𝑥{〈𝑦, ⦋𝑦 / 𝑥⦌𝐵〉} ⊆ ∪ 𝑥 ∈ 𝐴 {〈𝑥, 𝐵〉} | 
| 12 |  | id 22 | . . . . . . . . . . 11
⊢ (𝑥 = 𝑦 → 𝑥 = 𝑦) | 
| 13 |  | csbeq1a 3913 | . . . . . . . . . . 11
⊢ (𝑥 = 𝑦 → 𝐵 = ⦋𝑦 / 𝑥⦌𝐵) | 
| 14 | 12, 13 | opeq12d 4881 | . . . . . . . . . 10
⊢ (𝑥 = 𝑦 → 〈𝑥, 𝐵〉 = 〈𝑦, ⦋𝑦 / 𝑥⦌𝐵〉) | 
| 15 | 14 | sneqd 4638 | . . . . . . . . 9
⊢ (𝑥 = 𝑦 → {〈𝑥, 𝐵〉} = {〈𝑦, ⦋𝑦 / 𝑥⦌𝐵〉}) | 
| 16 | 15 | sseq1d 4015 | . . . . . . . 8
⊢ (𝑥 = 𝑦 → ({〈𝑥, 𝐵〉} ⊆ ∪ 𝑥 ∈ 𝐴 {〈𝑥, 𝐵〉} ↔ {〈𝑦, ⦋𝑦 / 𝑥⦌𝐵〉} ⊆ ∪ 𝑥 ∈ 𝐴 {〈𝑥, 𝐵〉})) | 
| 17 | 7, 11, 16, 6 | vtoclgaf 3576 | . . . . . . 7
⊢ (𝑦 ∈ 𝐴 → {〈𝑦, ⦋𝑦 / 𝑥⦌𝐵〉} ⊆ ∪ 𝑥 ∈ 𝐴 {〈𝑥, 𝐵〉}) | 
| 18 | 6, 17 | anim12i 613 | . . . . . 6
⊢ ((𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐴) → ({〈𝑥, 𝐵〉} ⊆ ∪ 𝑥 ∈ 𝐴 {〈𝑥, 𝐵〉} ∧ {〈𝑦, ⦋𝑦 / 𝑥⦌𝐵〉} ⊆ ∪ 𝑥 ∈ 𝐴 {〈𝑥, 𝐵〉})) | 
| 19 |  | unss 4190 | . . . . . . 7
⊢
(({〈𝑥, 𝐵〉} ⊆ ∪ 𝑥 ∈ 𝐴 {〈𝑥, 𝐵〉} ∧ {〈𝑦, ⦋𝑦 / 𝑥⦌𝐵〉} ⊆ ∪ 𝑥 ∈ 𝐴 {〈𝑥, 𝐵〉}) ↔ ({〈𝑥, 𝐵〉} ∪ {〈𝑦, ⦋𝑦 / 𝑥⦌𝐵〉}) ⊆ ∪ 𝑥 ∈ 𝐴 {〈𝑥, 𝐵〉}) | 
| 20 |  | sseq2 4010 | . . . . . . . . 9
⊢ (∪ 𝑥 ∈ 𝐴 {〈𝑥, 𝐵〉} = 〈𝐶, 𝐷〉 → (({〈𝑥, 𝐵〉} ∪ {〈𝑦, ⦋𝑦 / 𝑥⦌𝐵〉}) ⊆ ∪ 𝑥 ∈ 𝐴 {〈𝑥, 𝐵〉} ↔ ({〈𝑥, 𝐵〉} ∪ {〈𝑦, ⦋𝑦 / 𝑥⦌𝐵〉}) ⊆ 〈𝐶, 𝐷〉)) | 
| 21 |  | df-pr 4629 | . . . . . . . . . . . 12
⊢
{〈𝑥, 𝐵〉, 〈𝑦, ⦋𝑦 / 𝑥⦌𝐵〉} = ({〈𝑥, 𝐵〉} ∪ {〈𝑦, ⦋𝑦 / 𝑥⦌𝐵〉}) | 
| 22 | 21 | eqcomi 2746 | . . . . . . . . . . 11
⊢
({〈𝑥, 𝐵〉} ∪ {〈𝑦, ⦋𝑦 / 𝑥⦌𝐵〉}) = {〈𝑥, 𝐵〉, 〈𝑦, ⦋𝑦 / 𝑥⦌𝐵〉} | 
| 23 | 22 | sseq1i 4012 | . . . . . . . . . 10
⊢
(({〈𝑥, 𝐵〉} ∪ {〈𝑦, ⦋𝑦 / 𝑥⦌𝐵〉}) ⊆ 〈𝐶, 𝐷〉 ↔ {〈𝑥, 𝐵〉, 〈𝑦, ⦋𝑦 / 𝑥⦌𝐵〉} ⊆ 〈𝐶, 𝐷〉) | 
| 24 |  | vex 3484 | . . . . . . . . . . . 12
⊢ 𝑥 ∈ V | 
| 25 |  | iunopeqop.b | . . . . . . . . . . . 12
⊢ 𝐵 ∈ V | 
| 26 |  | vex 3484 | . . . . . . . . . . . 12
⊢ 𝑦 ∈ V | 
| 27 | 25 | csbex 5311 | . . . . . . . . . . . 12
⊢
⦋𝑦 /
𝑥⦌𝐵 ∈ V | 
| 28 |  | iunopeqop.c | . . . . . . . . . . . 12
⊢ 𝐶 ∈ V | 
| 29 |  | iunopeqop.d | . . . . . . . . . . . 12
⊢ 𝐷 ∈ V | 
| 30 | 24, 25, 26, 27, 28, 29 | propssopi 5513 | . . . . . . . . . . 11
⊢
({〈𝑥, 𝐵〉, 〈𝑦, ⦋𝑦 / 𝑥⦌𝐵〉} ⊆ 〈𝐶, 𝐷〉 → 𝑥 = 𝑦) | 
| 31 |  | eqneqall 2951 | . . . . . . . . . . 11
⊢ (𝑥 = 𝑦 → (𝑥 ≠ 𝑦 → ((𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐴) → ∃𝑧 𝐴 = {𝑧}))) | 
| 32 | 30, 31 | syl 17 | . . . . . . . . . 10
⊢
({〈𝑥, 𝐵〉, 〈𝑦, ⦋𝑦 / 𝑥⦌𝐵〉} ⊆ 〈𝐶, 𝐷〉 → (𝑥 ≠ 𝑦 → ((𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐴) → ∃𝑧 𝐴 = {𝑧}))) | 
| 33 | 23, 32 | sylbi 217 | . . . . . . . . 9
⊢
(({〈𝑥, 𝐵〉} ∪ {〈𝑦, ⦋𝑦 / 𝑥⦌𝐵〉}) ⊆ 〈𝐶, 𝐷〉 → (𝑥 ≠ 𝑦 → ((𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐴) → ∃𝑧 𝐴 = {𝑧}))) | 
| 34 | 20, 33 | biimtrdi 253 | . . . . . . . 8
⊢ (∪ 𝑥 ∈ 𝐴 {〈𝑥, 𝐵〉} = 〈𝐶, 𝐷〉 → (({〈𝑥, 𝐵〉} ∪ {〈𝑦, ⦋𝑦 / 𝑥⦌𝐵〉}) ⊆ ∪ 𝑥 ∈ 𝐴 {〈𝑥, 𝐵〉} → (𝑥 ≠ 𝑦 → ((𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐴) → ∃𝑧 𝐴 = {𝑧})))) | 
| 35 | 34 | com14 96 | . . . . . . 7
⊢ ((𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐴) → (({〈𝑥, 𝐵〉} ∪ {〈𝑦, ⦋𝑦 / 𝑥⦌𝐵〉}) ⊆ ∪ 𝑥 ∈ 𝐴 {〈𝑥, 𝐵〉} → (𝑥 ≠ 𝑦 → (∪
𝑥 ∈ 𝐴 {〈𝑥, 𝐵〉} = 〈𝐶, 𝐷〉 → ∃𝑧 𝐴 = {𝑧})))) | 
| 36 | 19, 35 | biimtrid 242 | . . . . . 6
⊢ ((𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐴) → (({〈𝑥, 𝐵〉} ⊆ ∪ 𝑥 ∈ 𝐴 {〈𝑥, 𝐵〉} ∧ {〈𝑦, ⦋𝑦 / 𝑥⦌𝐵〉} ⊆ ∪ 𝑥 ∈ 𝐴 {〈𝑥, 𝐵〉}) → (𝑥 ≠ 𝑦 → (∪
𝑥 ∈ 𝐴 {〈𝑥, 𝐵〉} = 〈𝐶, 𝐷〉 → ∃𝑧 𝐴 = {𝑧})))) | 
| 37 | 18, 36 | mpd 15 | . . . . 5
⊢ ((𝑥 ∈ 𝐴 ∧ 𝑦 ∈ 𝐴) → (𝑥 ≠ 𝑦 → (∪
𝑥 ∈ 𝐴 {〈𝑥, 𝐵〉} = 〈𝐶, 𝐷〉 → ∃𝑧 𝐴 = {𝑧}))) | 
| 38 | 37 | rexlimdva 3155 | . . . 4
⊢ (𝑥 ∈ 𝐴 → (∃𝑦 ∈ 𝐴 𝑥 ≠ 𝑦 → (∪
𝑥 ∈ 𝐴 {〈𝑥, 𝐵〉} = 〈𝐶, 𝐷〉 → ∃𝑧 𝐴 = {𝑧}))) | 
| 39 | 5, 38 | rexlimi 3259 | . . 3
⊢
(∃𝑥 ∈
𝐴 ∃𝑦 ∈ 𝐴 𝑥 ≠ 𝑦 → (∪
𝑥 ∈ 𝐴 {〈𝑥, 𝐵〉} = 〈𝐶, 𝐷〉 → ∃𝑧 𝐴 = {𝑧})) | 
| 40 |  | ax-1 6 | . . 3
⊢
(∃𝑧 𝐴 = {𝑧} → (∪
𝑥 ∈ 𝐴 {〈𝑥, 𝐵〉} = 〈𝐶, 𝐷〉 → ∃𝑧 𝐴 = {𝑧})) | 
| 41 | 39, 40 | jaoi 858 | . 2
⊢
((∃𝑥 ∈
𝐴 ∃𝑦 ∈ 𝐴 𝑥 ≠ 𝑦 ∨ ∃𝑧 𝐴 = {𝑧}) → (∪ 𝑥 ∈ 𝐴 {〈𝑥, 𝐵〉} = 〈𝐶, 𝐷〉 → ∃𝑧 𝐴 = {𝑧})) | 
| 42 | 1, 41 | syl 17 | 1
⊢ (𝐴 ≠ ∅ → (∪ 𝑥 ∈ 𝐴 {〈𝑥, 𝐵〉} = 〈𝐶, 𝐷〉 → ∃𝑧 𝐴 = {𝑧})) |