Proof of Theorem 2ndval
| Step | Hyp | Ref
| Expression |
| 1 | | snex 2745 |
. . . . 5
⊢ {A}
∈ V |
| 2 | | rnexg 3353 |
. . . . 5
⊢ ({A}
∈ V → ran { A} ∈
V) |
| 3 | 1, 2 | ax-mp 7 |
. . . 4
⊢ ran { A} ∈ V |
| 4 | 3 | uniex 2865 |
. . 3
⊢ ∪ran { A} ∈ V |
| 5 | | sneq 2413 |
. . . . . . 7
⊢ (x =
A → {x} = {A}) |
| 6 | 5 | rneqd 3336 |
. . . . . 6
⊢ (x =
A → ran { x} = ran { A}) |
| 7 | 6 | unieqd 2507 |
. . . . 5
⊢ (x =
A → ∪ran {
x} = ∪ran {
A}) |
| 8 | 7 | fvopabg 3776 |
. . . 4
⊢ ((A
∈ V ⋀ ∪ran { A} ∈ V) → ({〈x, y〉∣y
= ∪ran { x}}
‘A) = ∪ran
{ A}) |
| 9 | | df-2nd 4070 |
. . . . 5
⊢ 2nd = {〈x, y〉∣y
= ∪ran { x}} |
| 10 | 9 | fveq1i 3716 |
. . . 4
⊢ (2nd ‘A) = ({〈x,
y〉∣y = ∪ran { x}} ‘A) |
| 11 | 8, 10 | syl5eq 1516 |
. . 3
⊢ ((A
∈ V ⋀ ∪ran { A} ∈ V) → (2nd
‘A) = ∪ran
{ A}) |
| 12 | 4, 11 | mpan2 695 |
. 2
⊢ (A
∈ V → (2nd ‘A) = ∪ran { A}) |
| 13 | | fvprc 3712 |
. . 3
⊢ (¬ A ∈ V → (2nd
‘A) = ∅) |
| 14 | | snprc 2439 |
. . . . . . . 8
⊢ (¬ A ∈ V ↔ {A} = ∅) |
| 15 | 14 | biimp 151 |
. . . . . . 7
⊢ (¬ A ∈ V → {A} = ∅) |
| 16 | 15 | rneqd 3336 |
. . . . . 6
⊢ (¬ A ∈ V → ran { A} = ran ∅) |
| 17 | | rn0 3349 |
. . . . . 6
⊢ ran ∅ = ∅ |
| 18 | 16, 17 | syl6eq 1520 |
. . . . 5
⊢ (¬ A ∈ V → ran { A} = ∅) |
| 19 | 18 | unieqd 2507 |
. . . 4
⊢ (¬ A ∈ V → ∪ran { A} = ∪∅) |
| 20 | | uni0 2520 |
. . . 4
⊢ ∪∅ =
∅ |
| 21 | 19, 20 | syl6eq 1520 |
. . 3
⊢ (¬ A ∈ V → ∪ran { A} =
∅) |
| 22 | 13, 21 | eqtr4d 1507 |
. 2
⊢ (¬ A ∈ V → (2nd
‘A) = ∪ran
{ A}) |
| 23 | 12, 22 | pm2.61i 126 |
1
⊢ (2nd ‘A) = ∪ran { A} |