| Step |
Hyp |
Ref |
Expression |
| 1 |
|
eceqoveq.5 |
|- .~ Er ( S X. S ) |
| 2 |
|
eceqoveq.7 |
|- dom .+ = ( S X. S ) |
| 3 |
|
eceqoveq.8 |
|- -. (/) e. S |
| 4 |
|
eceqoveq.9 |
|- ( ( x e. S /\ y e. S ) -> ( x .+ y ) e. S ) |
| 5 |
|
eceqoveq.10 |
|- ( ( ( A e. S /\ B e. S ) /\ ( C e. S /\ D e. S ) ) -> ( <. A , B >. .~ <. C , D >. <-> ( A .+ D ) = ( B .+ C ) ) ) |
| 6 |
|
opelxpi |
|- ( ( A e. S /\ B e. S ) -> <. A , B >. e. ( S X. S ) ) |
| 7 |
6
|
ad2antrr |
|- ( ( ( ( A e. S /\ B e. S ) /\ C e. S ) /\ [ <. A , B >. ] .~ = [ <. C , D >. ] .~ ) -> <. A , B >. e. ( S X. S ) ) |
| 8 |
1
|
a1i |
|- ( ( ( ( A e. S /\ B e. S ) /\ C e. S ) /\ [ <. A , B >. ] .~ = [ <. C , D >. ] .~ ) -> .~ Er ( S X. S ) ) |
| 9 |
|
simpr |
|- ( ( ( ( A e. S /\ B e. S ) /\ C e. S ) /\ [ <. A , B >. ] .~ = [ <. C , D >. ] .~ ) -> [ <. A , B >. ] .~ = [ <. C , D >. ] .~ ) |
| 10 |
8 9
|
ereldm |
|- ( ( ( ( A e. S /\ B e. S ) /\ C e. S ) /\ [ <. A , B >. ] .~ = [ <. C , D >. ] .~ ) -> ( <. A , B >. e. ( S X. S ) <-> <. C , D >. e. ( S X. S ) ) ) |
| 11 |
7 10
|
mpbid |
|- ( ( ( ( A e. S /\ B e. S ) /\ C e. S ) /\ [ <. A , B >. ] .~ = [ <. C , D >. ] .~ ) -> <. C , D >. e. ( S X. S ) ) |
| 12 |
|
opelxp2 |
|- ( <. C , D >. e. ( S X. S ) -> D e. S ) |
| 13 |
11 12
|
syl |
|- ( ( ( ( A e. S /\ B e. S ) /\ C e. S ) /\ [ <. A , B >. ] .~ = [ <. C , D >. ] .~ ) -> D e. S ) |
| 14 |
13
|
ex |
|- ( ( ( A e. S /\ B e. S ) /\ C e. S ) -> ( [ <. A , B >. ] .~ = [ <. C , D >. ] .~ -> D e. S ) ) |
| 15 |
4
|
caovcl |
|- ( ( B e. S /\ C e. S ) -> ( B .+ C ) e. S ) |
| 16 |
|
eleq1 |
|- ( ( A .+ D ) = ( B .+ C ) -> ( ( A .+ D ) e. S <-> ( B .+ C ) e. S ) ) |
| 17 |
15 16
|
imbitrrid |
|- ( ( A .+ D ) = ( B .+ C ) -> ( ( B e. S /\ C e. S ) -> ( A .+ D ) e. S ) ) |
| 18 |
2 3
|
ndmovrcl |
|- ( ( A .+ D ) e. S -> ( A e. S /\ D e. S ) ) |
| 19 |
18
|
simprd |
|- ( ( A .+ D ) e. S -> D e. S ) |
| 20 |
17 19
|
syl6com |
|- ( ( B e. S /\ C e. S ) -> ( ( A .+ D ) = ( B .+ C ) -> D e. S ) ) |
| 21 |
20
|
adantll |
|- ( ( ( A e. S /\ B e. S ) /\ C e. S ) -> ( ( A .+ D ) = ( B .+ C ) -> D e. S ) ) |
| 22 |
1
|
a1i |
|- ( ( ( A e. S /\ B e. S ) /\ ( C e. S /\ D e. S ) ) -> .~ Er ( S X. S ) ) |
| 23 |
6
|
adantr |
|- ( ( ( A e. S /\ B e. S ) /\ ( C e. S /\ D e. S ) ) -> <. A , B >. e. ( S X. S ) ) |
| 24 |
22 23
|
erth |
|- ( ( ( A e. S /\ B e. S ) /\ ( C e. S /\ D e. S ) ) -> ( <. A , B >. .~ <. C , D >. <-> [ <. A , B >. ] .~ = [ <. C , D >. ] .~ ) ) |
| 25 |
24 5
|
bitr3d |
|- ( ( ( A e. S /\ B e. S ) /\ ( C e. S /\ D e. S ) ) -> ( [ <. A , B >. ] .~ = [ <. C , D >. ] .~ <-> ( A .+ D ) = ( B .+ C ) ) ) |
| 26 |
25
|
expr |
|- ( ( ( A e. S /\ B e. S ) /\ C e. S ) -> ( D e. S -> ( [ <. A , B >. ] .~ = [ <. C , D >. ] .~ <-> ( A .+ D ) = ( B .+ C ) ) ) ) |
| 27 |
14 21 26
|
pm5.21ndd |
|- ( ( ( A e. S /\ B e. S ) /\ C e. S ) -> ( [ <. A , B >. ] .~ = [ <. C , D >. ] .~ <-> ( A .+ D ) = ( B .+ C ) ) ) |
| 28 |
27
|
an32s |
|- ( ( ( A e. S /\ C e. S ) /\ B e. S ) -> ( [ <. A , B >. ] .~ = [ <. C , D >. ] .~ <-> ( A .+ D ) = ( B .+ C ) ) ) |
| 29 |
|
eqcom |
|- ( (/) = [ <. C , D >. ] .~ <-> [ <. C , D >. ] .~ = (/) ) |
| 30 |
|
erdm |
|- ( .~ Er ( S X. S ) -> dom .~ = ( S X. S ) ) |
| 31 |
1 30
|
ax-mp |
|- dom .~ = ( S X. S ) |
| 32 |
31
|
eleq2i |
|- ( <. C , D >. e. dom .~ <-> <. C , D >. e. ( S X. S ) ) |
| 33 |
|
ecdmn0 |
|- ( <. C , D >. e. dom .~ <-> [ <. C , D >. ] .~ =/= (/) ) |
| 34 |
|
opelxp |
|- ( <. C , D >. e. ( S X. S ) <-> ( C e. S /\ D e. S ) ) |
| 35 |
32 33 34
|
3bitr3i |
|- ( [ <. C , D >. ] .~ =/= (/) <-> ( C e. S /\ D e. S ) ) |
| 36 |
35
|
simplbi2 |
|- ( C e. S -> ( D e. S -> [ <. C , D >. ] .~ =/= (/) ) ) |
| 37 |
36
|
ad2antlr |
|- ( ( ( A e. S /\ C e. S ) /\ -. B e. S ) -> ( D e. S -> [ <. C , D >. ] .~ =/= (/) ) ) |
| 38 |
37
|
necon2bd |
|- ( ( ( A e. S /\ C e. S ) /\ -. B e. S ) -> ( [ <. C , D >. ] .~ = (/) -> -. D e. S ) ) |
| 39 |
|
simpr |
|- ( ( A e. S /\ D e. S ) -> D e. S ) |
| 40 |
2
|
ndmov |
|- ( -. ( A e. S /\ D e. S ) -> ( A .+ D ) = (/) ) |
| 41 |
39 40
|
nsyl5 |
|- ( -. D e. S -> ( A .+ D ) = (/) ) |
| 42 |
38 41
|
syl6 |
|- ( ( ( A e. S /\ C e. S ) /\ -. B e. S ) -> ( [ <. C , D >. ] .~ = (/) -> ( A .+ D ) = (/) ) ) |
| 43 |
|
eleq1 |
|- ( ( A .+ D ) = (/) -> ( ( A .+ D ) e. S <-> (/) e. S ) ) |
| 44 |
3 43
|
mtbiri |
|- ( ( A .+ D ) = (/) -> -. ( A .+ D ) e. S ) |
| 45 |
35
|
simprbi |
|- ( [ <. C , D >. ] .~ =/= (/) -> D e. S ) |
| 46 |
4
|
caovcl |
|- ( ( A e. S /\ D e. S ) -> ( A .+ D ) e. S ) |
| 47 |
46
|
ex |
|- ( A e. S -> ( D e. S -> ( A .+ D ) e. S ) ) |
| 48 |
47
|
ad2antrr |
|- ( ( ( A e. S /\ C e. S ) /\ -. B e. S ) -> ( D e. S -> ( A .+ D ) e. S ) ) |
| 49 |
45 48
|
syl5 |
|- ( ( ( A e. S /\ C e. S ) /\ -. B e. S ) -> ( [ <. C , D >. ] .~ =/= (/) -> ( A .+ D ) e. S ) ) |
| 50 |
49
|
necon1bd |
|- ( ( ( A e. S /\ C e. S ) /\ -. B e. S ) -> ( -. ( A .+ D ) e. S -> [ <. C , D >. ] .~ = (/) ) ) |
| 51 |
44 50
|
syl5 |
|- ( ( ( A e. S /\ C e. S ) /\ -. B e. S ) -> ( ( A .+ D ) = (/) -> [ <. C , D >. ] .~ = (/) ) ) |
| 52 |
42 51
|
impbid |
|- ( ( ( A e. S /\ C e. S ) /\ -. B e. S ) -> ( [ <. C , D >. ] .~ = (/) <-> ( A .+ D ) = (/) ) ) |
| 53 |
29 52
|
bitrid |
|- ( ( ( A e. S /\ C e. S ) /\ -. B e. S ) -> ( (/) = [ <. C , D >. ] .~ <-> ( A .+ D ) = (/) ) ) |
| 54 |
31
|
eleq2i |
|- ( <. A , B >. e. dom .~ <-> <. A , B >. e. ( S X. S ) ) |
| 55 |
|
ecdmn0 |
|- ( <. A , B >. e. dom .~ <-> [ <. A , B >. ] .~ =/= (/) ) |
| 56 |
|
opelxp |
|- ( <. A , B >. e. ( S X. S ) <-> ( A e. S /\ B e. S ) ) |
| 57 |
54 55 56
|
3bitr3i |
|- ( [ <. A , B >. ] .~ =/= (/) <-> ( A e. S /\ B e. S ) ) |
| 58 |
57
|
simprbi |
|- ( [ <. A , B >. ] .~ =/= (/) -> B e. S ) |
| 59 |
58
|
necon1bi |
|- ( -. B e. S -> [ <. A , B >. ] .~ = (/) ) |
| 60 |
59
|
adantl |
|- ( ( ( A e. S /\ C e. S ) /\ -. B e. S ) -> [ <. A , B >. ] .~ = (/) ) |
| 61 |
60
|
eqeq1d |
|- ( ( ( A e. S /\ C e. S ) /\ -. B e. S ) -> ( [ <. A , B >. ] .~ = [ <. C , D >. ] .~ <-> (/) = [ <. C , D >. ] .~ ) ) |
| 62 |
|
simpl |
|- ( ( B e. S /\ C e. S ) -> B e. S ) |
| 63 |
2
|
ndmov |
|- ( -. ( B e. S /\ C e. S ) -> ( B .+ C ) = (/) ) |
| 64 |
62 63
|
nsyl5 |
|- ( -. B e. S -> ( B .+ C ) = (/) ) |
| 65 |
64
|
adantl |
|- ( ( ( A e. S /\ C e. S ) /\ -. B e. S ) -> ( B .+ C ) = (/) ) |
| 66 |
65
|
eqeq2d |
|- ( ( ( A e. S /\ C e. S ) /\ -. B e. S ) -> ( ( A .+ D ) = ( B .+ C ) <-> ( A .+ D ) = (/) ) ) |
| 67 |
53 61 66
|
3bitr4d |
|- ( ( ( A e. S /\ C e. S ) /\ -. B e. S ) -> ( [ <. A , B >. ] .~ = [ <. C , D >. ] .~ <-> ( A .+ D ) = ( B .+ C ) ) ) |
| 68 |
28 67
|
pm2.61dan |
|- ( ( A e. S /\ C e. S ) -> ( [ <. A , B >. ] .~ = [ <. C , D >. ] .~ <-> ( A .+ D ) = ( B .+ C ) ) ) |