Step |
Hyp |
Ref |
Expression |
1 |
|
uniun |
⊢ ∪ ( ( 𝐴 ∖ { ∅ } ) ∪ { ∅ } ) = ( ∪ ( 𝐴 ∖ { ∅ } ) ∪ ∪ { ∅ } ) |
2 |
|
undif1 |
⊢ ( ( 𝐴 ∖ { ∅ } ) ∪ { ∅ } ) = ( 𝐴 ∪ { ∅ } ) |
3 |
|
uncom |
⊢ ( 𝐴 ∪ { ∅ } ) = ( { ∅ } ∪ 𝐴 ) |
4 |
2 3
|
eqtr2i |
⊢ ( { ∅ } ∪ 𝐴 ) = ( ( 𝐴 ∖ { ∅ } ) ∪ { ∅ } ) |
5 |
4
|
unieqi |
⊢ ∪ ( { ∅ } ∪ 𝐴 ) = ∪ ( ( 𝐴 ∖ { ∅ } ) ∪ { ∅ } ) |
6 |
|
0ex |
⊢ ∅ ∈ V |
7 |
6
|
unisn |
⊢ ∪ { ∅ } = ∅ |
8 |
7
|
uneq2i |
⊢ ( ∪ ( 𝐴 ∖ { ∅ } ) ∪ ∪ { ∅ } ) = ( ∪ ( 𝐴 ∖ { ∅ } ) ∪ ∅ ) |
9 |
|
un0 |
⊢ ( ∪ ( 𝐴 ∖ { ∅ } ) ∪ ∅ ) = ∪ ( 𝐴 ∖ { ∅ } ) |
10 |
8 9
|
eqtr2i |
⊢ ∪ ( 𝐴 ∖ { ∅ } ) = ( ∪ ( 𝐴 ∖ { ∅ } ) ∪ ∪ { ∅ } ) |
11 |
1 5 10
|
3eqtr4ri |
⊢ ∪ ( 𝐴 ∖ { ∅ } ) = ∪ ( { ∅ } ∪ 𝐴 ) |
12 |
|
uniun |
⊢ ∪ ( { ∅ } ∪ 𝐴 ) = ( ∪ { ∅ } ∪ ∪ 𝐴 ) |
13 |
7
|
uneq1i |
⊢ ( ∪ { ∅ } ∪ ∪ 𝐴 ) = ( ∅ ∪ ∪ 𝐴 ) |
14 |
11 12 13
|
3eqtri |
⊢ ∪ ( 𝐴 ∖ { ∅ } ) = ( ∅ ∪ ∪ 𝐴 ) |
15 |
|
uncom |
⊢ ( ∅ ∪ ∪ 𝐴 ) = ( ∪ 𝐴 ∪ ∅ ) |
16 |
|
un0 |
⊢ ( ∪ 𝐴 ∪ ∅ ) = ∪ 𝐴 |
17 |
14 15 16
|
3eqtri |
⊢ ∪ ( 𝐴 ∖ { ∅ } ) = ∪ 𝐴 |