| Step | Hyp | Ref
 | Expression | 
| 1 |   | sneq 3633 | 
. . . 4
⊢ (𝑧 = 𝐴 → {𝑧} = {𝐴}) | 
| 2 | 1 | ixpeq1d 6769 | 
. . 3
⊢ (𝑧 = 𝐴 → X𝑥 ∈ {𝑧}𝐵 = X𝑥 ∈ {𝐴}𝐵) | 
| 3 | 2 | eleq2d 2266 | 
. 2
⊢ (𝑧 = 𝐴 → (𝐹 ∈ X𝑥 ∈ {𝑧}𝐵 ↔ 𝐹 ∈ X𝑥 ∈ {𝐴}𝐵)) | 
| 4 |   | opeq1 3808 | 
. . . . 5
⊢ (𝑧 = 𝐴 → 〈𝑧, 𝑦〉 = 〈𝐴, 𝑦〉) | 
| 5 | 4 | sneqd 3635 | 
. . . 4
⊢ (𝑧 = 𝐴 → {〈𝑧, 𝑦〉} = {〈𝐴, 𝑦〉}) | 
| 6 | 5 | eqeq2d 2208 | 
. . 3
⊢ (𝑧 = 𝐴 → (𝐹 = {〈𝑧, 𝑦〉} ↔ 𝐹 = {〈𝐴, 𝑦〉})) | 
| 7 | 6 | rexbidv 2498 | 
. 2
⊢ (𝑧 = 𝐴 → (∃𝑦 ∈ 𝐵 𝐹 = {〈𝑧, 𝑦〉} ↔ ∃𝑦 ∈ 𝐵 𝐹 = {〈𝐴, 𝑦〉})) | 
| 8 |   | elex 2774 | 
. . 3
⊢ (𝐹 ∈ X𝑥 ∈
{𝑧}𝐵 → 𝐹 ∈ V) | 
| 9 |   | vex 2766 | 
. . . . . . 7
⊢ 𝑧 ∈ V | 
| 10 |   | vex 2766 | 
. . . . . . 7
⊢ 𝑦 ∈ V | 
| 11 | 9, 10 | opex 4262 | 
. . . . . 6
⊢
〈𝑧, 𝑦〉 ∈ V | 
| 12 | 11 | snex 4218 | 
. . . . 5
⊢
{〈𝑧, 𝑦〉} ∈
V | 
| 13 |   | eleq1 2259 | 
. . . . 5
⊢ (𝐹 = {〈𝑧, 𝑦〉} → (𝐹 ∈ V ↔ {〈𝑧, 𝑦〉} ∈ V)) | 
| 14 | 12, 13 | mpbiri 168 | 
. . . 4
⊢ (𝐹 = {〈𝑧, 𝑦〉} → 𝐹 ∈ V) | 
| 15 | 14 | rexlimivw 2610 | 
. . 3
⊢
(∃𝑦 ∈
𝐵 𝐹 = {〈𝑧, 𝑦〉} → 𝐹 ∈ V) | 
| 16 |   | eleq1 2259 | 
. . . 4
⊢ (𝑤 = 𝐹 → (𝑤 ∈ X𝑥 ∈ {𝑧}𝐵 ↔ 𝐹 ∈ X𝑥 ∈ {𝑧}𝐵)) | 
| 17 |   | eqeq1 2203 | 
. . . . 5
⊢ (𝑤 = 𝐹 → (𝑤 = {〈𝑧, 𝑦〉} ↔ 𝐹 = {〈𝑧, 𝑦〉})) | 
| 18 | 17 | rexbidv 2498 | 
. . . 4
⊢ (𝑤 = 𝐹 → (∃𝑦 ∈ 𝐵 𝑤 = {〈𝑧, 𝑦〉} ↔ ∃𝑦 ∈ 𝐵 𝐹 = {〈𝑧, 𝑦〉})) | 
| 19 |   | vex 2766 | 
. . . . . 6
⊢ 𝑤 ∈ V | 
| 20 | 19 | elixp 6764 | 
. . . . 5
⊢ (𝑤 ∈ X𝑥 ∈
{𝑧}𝐵 ↔ (𝑤 Fn {𝑧} ∧ ∀𝑥 ∈ {𝑧} (𝑤‘𝑥) ∈ 𝐵)) | 
| 21 |   | fveq2 5558 | 
. . . . . . . 8
⊢ (𝑥 = 𝑧 → (𝑤‘𝑥) = (𝑤‘𝑧)) | 
| 22 | 21 | eleq1d 2265 | 
. . . . . . 7
⊢ (𝑥 = 𝑧 → ((𝑤‘𝑥) ∈ 𝐵 ↔ (𝑤‘𝑧) ∈ 𝐵)) | 
| 23 | 9, 22 | ralsn 3665 | 
. . . . . 6
⊢
(∀𝑥 ∈
{𝑧} (𝑤‘𝑥) ∈ 𝐵 ↔ (𝑤‘𝑧) ∈ 𝐵) | 
| 24 | 23 | anbi2i 457 | 
. . . . 5
⊢ ((𝑤 Fn {𝑧} ∧ ∀𝑥 ∈ {𝑧} (𝑤‘𝑥) ∈ 𝐵) ↔ (𝑤 Fn {𝑧} ∧ (𝑤‘𝑧) ∈ 𝐵)) | 
| 25 |   | simpl 109 | 
. . . . . . . . 9
⊢ ((𝑤 Fn {𝑧} ∧ (𝑤‘𝑧) ∈ 𝐵) → 𝑤 Fn {𝑧}) | 
| 26 |   | fveq2 5558 | 
. . . . . . . . . . . . 13
⊢ (𝑦 = 𝑧 → (𝑤‘𝑦) = (𝑤‘𝑧)) | 
| 27 | 26 | eleq1d 2265 | 
. . . . . . . . . . . 12
⊢ (𝑦 = 𝑧 → ((𝑤‘𝑦) ∈ 𝐵 ↔ (𝑤‘𝑧) ∈ 𝐵)) | 
| 28 | 9, 27 | ralsn 3665 | 
. . . . . . . . . . 11
⊢
(∀𝑦 ∈
{𝑧} (𝑤‘𝑦) ∈ 𝐵 ↔ (𝑤‘𝑧) ∈ 𝐵) | 
| 29 | 28 | biimpri 133 | 
. . . . . . . . . 10
⊢ ((𝑤‘𝑧) ∈ 𝐵 → ∀𝑦 ∈ {𝑧} (𝑤‘𝑦) ∈ 𝐵) | 
| 30 | 29 | adantl 277 | 
. . . . . . . . 9
⊢ ((𝑤 Fn {𝑧} ∧ (𝑤‘𝑧) ∈ 𝐵) → ∀𝑦 ∈ {𝑧} (𝑤‘𝑦) ∈ 𝐵) | 
| 31 |   | ffnfv 5720 | 
. . . . . . . . 9
⊢ (𝑤:{𝑧}⟶𝐵 ↔ (𝑤 Fn {𝑧} ∧ ∀𝑦 ∈ {𝑧} (𝑤‘𝑦) ∈ 𝐵)) | 
| 32 | 25, 30, 31 | sylanbrc 417 | 
. . . . . . . 8
⊢ ((𝑤 Fn {𝑧} ∧ (𝑤‘𝑧) ∈ 𝐵) → 𝑤:{𝑧}⟶𝐵) | 
| 33 | 9 | fsn2 5736 | 
. . . . . . . 8
⊢ (𝑤:{𝑧}⟶𝐵 ↔ ((𝑤‘𝑧) ∈ 𝐵 ∧ 𝑤 = {〈𝑧, (𝑤‘𝑧)〉})) | 
| 34 | 32, 33 | sylib 122 | 
. . . . . . 7
⊢ ((𝑤 Fn {𝑧} ∧ (𝑤‘𝑧) ∈ 𝐵) → ((𝑤‘𝑧) ∈ 𝐵 ∧ 𝑤 = {〈𝑧, (𝑤‘𝑧)〉})) | 
| 35 |   | opeq2 3809 | 
. . . . . . . . 9
⊢ (𝑦 = (𝑤‘𝑧) → 〈𝑧, 𝑦〉 = 〈𝑧, (𝑤‘𝑧)〉) | 
| 36 | 35 | sneqd 3635 | 
. . . . . . . 8
⊢ (𝑦 = (𝑤‘𝑧) → {〈𝑧, 𝑦〉} = {〈𝑧, (𝑤‘𝑧)〉}) | 
| 37 | 36 | rspceeqv 2886 | 
. . . . . . 7
⊢ (((𝑤‘𝑧) ∈ 𝐵 ∧ 𝑤 = {〈𝑧, (𝑤‘𝑧)〉}) → ∃𝑦 ∈ 𝐵 𝑤 = {〈𝑧, 𝑦〉}) | 
| 38 | 34, 37 | syl 14 | 
. . . . . 6
⊢ ((𝑤 Fn {𝑧} ∧ (𝑤‘𝑧) ∈ 𝐵) → ∃𝑦 ∈ 𝐵 𝑤 = {〈𝑧, 𝑦〉}) | 
| 39 | 9, 10 | fvsn 5757 | 
. . . . . . . . . 10
⊢
({〈𝑧, 𝑦〉}‘𝑧) = 𝑦 | 
| 40 |   | id 19 | 
. . . . . . . . . 10
⊢ (𝑦 ∈ 𝐵 → 𝑦 ∈ 𝐵) | 
| 41 | 39, 40 | eqeltrid 2283 | 
. . . . . . . . 9
⊢ (𝑦 ∈ 𝐵 → ({〈𝑧, 𝑦〉}‘𝑧) ∈ 𝐵) | 
| 42 | 9, 10 | fnsn 5312 | 
. . . . . . . . 9
⊢
{〈𝑧, 𝑦〉} Fn {𝑧} | 
| 43 | 41, 42 | jctil 312 | 
. . . . . . . 8
⊢ (𝑦 ∈ 𝐵 → ({〈𝑧, 𝑦〉} Fn {𝑧} ∧ ({〈𝑧, 𝑦〉}‘𝑧) ∈ 𝐵)) | 
| 44 |   | fneq1 5346 | 
. . . . . . . . 9
⊢ (𝑤 = {〈𝑧, 𝑦〉} → (𝑤 Fn {𝑧} ↔ {〈𝑧, 𝑦〉} Fn {𝑧})) | 
| 45 |   | fveq1 5557 | 
. . . . . . . . . 10
⊢ (𝑤 = {〈𝑧, 𝑦〉} → (𝑤‘𝑧) = ({〈𝑧, 𝑦〉}‘𝑧)) | 
| 46 | 45 | eleq1d 2265 | 
. . . . . . . . 9
⊢ (𝑤 = {〈𝑧, 𝑦〉} → ((𝑤‘𝑧) ∈ 𝐵 ↔ ({〈𝑧, 𝑦〉}‘𝑧) ∈ 𝐵)) | 
| 47 | 44, 46 | anbi12d 473 | 
. . . . . . . 8
⊢ (𝑤 = {〈𝑧, 𝑦〉} → ((𝑤 Fn {𝑧} ∧ (𝑤‘𝑧) ∈ 𝐵) ↔ ({〈𝑧, 𝑦〉} Fn {𝑧} ∧ ({〈𝑧, 𝑦〉}‘𝑧) ∈ 𝐵))) | 
| 48 | 43, 47 | syl5ibrcom 157 | 
. . . . . . 7
⊢ (𝑦 ∈ 𝐵 → (𝑤 = {〈𝑧, 𝑦〉} → (𝑤 Fn {𝑧} ∧ (𝑤‘𝑧) ∈ 𝐵))) | 
| 49 | 48 | rexlimiv 2608 | 
. . . . . 6
⊢
(∃𝑦 ∈
𝐵 𝑤 = {〈𝑧, 𝑦〉} → (𝑤 Fn {𝑧} ∧ (𝑤‘𝑧) ∈ 𝐵)) | 
| 50 | 38, 49 | impbii 126 | 
. . . . 5
⊢ ((𝑤 Fn {𝑧} ∧ (𝑤‘𝑧) ∈ 𝐵) ↔ ∃𝑦 ∈ 𝐵 𝑤 = {〈𝑧, 𝑦〉}) | 
| 51 | 20, 24, 50 | 3bitri 206 | 
. . . 4
⊢ (𝑤 ∈ X𝑥 ∈
{𝑧}𝐵 ↔ ∃𝑦 ∈ 𝐵 𝑤 = {〈𝑧, 𝑦〉}) | 
| 52 | 16, 18, 51 | vtoclbg 2825 | 
. . 3
⊢ (𝐹 ∈ V → (𝐹 ∈ X𝑥 ∈
{𝑧}𝐵 ↔ ∃𝑦 ∈ 𝐵 𝐹 = {〈𝑧, 𝑦〉})) | 
| 53 | 8, 15, 52 | pm5.21nii 705 | 
. 2
⊢ (𝐹 ∈ X𝑥 ∈
{𝑧}𝐵 ↔ ∃𝑦 ∈ 𝐵 𝐹 = {〈𝑧, 𝑦〉}) | 
| 54 | 3, 7, 53 | vtoclbg 2825 | 
1
⊢ (𝐴 ∈ 𝑉 → (𝐹 ∈ X𝑥 ∈ {𝐴}𝐵 ↔ ∃𝑦 ∈ 𝐵 𝐹 = {〈𝐴, 𝑦〉})) |