Proof of Theorem fvex
| Step | Hyp | Ref
| Expression |
| 1 | | df-fv 3198 |
. 2
⊢ (F
‘A) = ∪{x∣(F “ {A}) =
{x}} |
| 2 | | moeq 1916 |
. . . . 5
⊢ ∃*x x = ∪(F “ {A}) |
| 3 | | unieq 2506 |
. . . . . . 7
⊢ ((F
“ {A}) = {x} → ∪(F “ {A}) =
∪{x}) |
| 4 | | visset 1809 |
. . . . . . . 8
⊢ x
∈ V |
| 5 | 4 | unisn 2513 |
. . . . . . 7
⊢ ∪{x} = x |
| 6 | 3, 5 | syl6req 1521 |
. . . . . 6
⊢ ((F
“ {A}) = {x} → x =
∪(F “
{A})) |
| 7 | 6 | immoi 1416 |
. . . . 5
⊢ (∃*x x = ∪(F “ {A}) → ∃*x(F “
{A}) = {x}) |
| 8 | 2, 7 | ax-mp 7 |
. . . 4
⊢ ∃*x(F “
{A}) = {x} |
| 9 | | moabex 2762 |
. . . 4
⊢ (∃*x(F “
{A}) = {x} → {x∣(F
“ {A}) = {x}} ∈ V) |
| 10 | 8, 9 | ax-mp 7 |
. . 3
⊢ {x∣(F
“ {A}) = {x}} ∈ V |
| 11 | 10 | uniex 2869 |
. 2
⊢ ∪{x∣(F
“ {A}) = {x}} ∈ V |
| 12 | 1, 11 | eqeltr 1541 |
1
⊢ (F
‘A) ∈ V |