Step |
Hyp |
Ref |
Expression |
1 |
|
madebday |
|- ( ( A e. On /\ X e. No ) -> ( X e. ( _M ` A ) <-> ( bday ` X ) C_ A ) ) |
2 |
|
oldbday |
|- ( ( A e. On /\ X e. No ) -> ( X e. ( _Old ` A ) <-> ( bday ` X ) e. A ) ) |
3 |
2
|
notbid |
|- ( ( A e. On /\ X e. No ) -> ( -. X e. ( _Old ` A ) <-> -. ( bday ` X ) e. A ) ) |
4 |
1 3
|
anbi12d |
|- ( ( A e. On /\ X e. No ) -> ( ( X e. ( _M ` A ) /\ -. X e. ( _Old ` A ) ) <-> ( ( bday ` X ) C_ A /\ -. ( bday ` X ) e. A ) ) ) |
5 |
|
newval |
|- ( _N ` A ) = ( ( _M ` A ) \ ( _Old ` A ) ) |
6 |
5
|
a1i |
|- ( A e. On -> ( _N ` A ) = ( ( _M ` A ) \ ( _Old ` A ) ) ) |
7 |
6
|
eleq2d |
|- ( A e. On -> ( X e. ( _N ` A ) <-> X e. ( ( _M ` A ) \ ( _Old ` A ) ) ) ) |
8 |
|
eldif |
|- ( X e. ( ( _M ` A ) \ ( _Old ` A ) ) <-> ( X e. ( _M ` A ) /\ -. X e. ( _Old ` A ) ) ) |
9 |
7 8
|
bitrdi |
|- ( A e. On -> ( X e. ( _N ` A ) <-> ( X e. ( _M ` A ) /\ -. X e. ( _Old ` A ) ) ) ) |
10 |
9
|
adantr |
|- ( ( A e. On /\ X e. No ) -> ( X e. ( _N ` A ) <-> ( X e. ( _M ` A ) /\ -. X e. ( _Old ` A ) ) ) ) |
11 |
|
bdayelon |
|- ( bday ` X ) e. On |
12 |
11
|
onordi |
|- Ord ( bday ` X ) |
13 |
|
eloni |
|- ( A e. On -> Ord A ) |
14 |
|
ordtri4 |
|- ( ( Ord ( bday ` X ) /\ Ord A ) -> ( ( bday ` X ) = A <-> ( ( bday ` X ) C_ A /\ -. ( bday ` X ) e. A ) ) ) |
15 |
12 13 14
|
sylancr |
|- ( A e. On -> ( ( bday ` X ) = A <-> ( ( bday ` X ) C_ A /\ -. ( bday ` X ) e. A ) ) ) |
16 |
15
|
adantr |
|- ( ( A e. On /\ X e. No ) -> ( ( bday ` X ) = A <-> ( ( bday ` X ) C_ A /\ -. ( bday ` X ) e. A ) ) ) |
17 |
4 10 16
|
3bitr4d |
|- ( ( A e. On /\ X e. No ) -> ( X e. ( _N ` A ) <-> ( bday ` X ) = A ) ) |