Step |
Hyp |
Ref |
Expression |
1 |
|
breq1 |
|- ( x = B -> ( x R y <-> B R y ) ) |
2 |
|
eqeq1 |
|- ( x = B -> ( x = y <-> B = y ) ) |
3 |
|
breq2 |
|- ( x = B -> ( y R x <-> y R B ) ) |
4 |
1 2 3
|
3orbi123d |
|- ( x = B -> ( ( x R y \/ x = y \/ y R x ) <-> ( B R y \/ B = y \/ y R B ) ) ) |
5 |
4
|
imbi2d |
|- ( x = B -> ( ( R Or A -> ( x R y \/ x = y \/ y R x ) ) <-> ( R Or A -> ( B R y \/ B = y \/ y R B ) ) ) ) |
6 |
|
breq2 |
|- ( y = C -> ( B R y <-> B R C ) ) |
7 |
|
eqeq2 |
|- ( y = C -> ( B = y <-> B = C ) ) |
8 |
|
breq1 |
|- ( y = C -> ( y R B <-> C R B ) ) |
9 |
6 7 8
|
3orbi123d |
|- ( y = C -> ( ( B R y \/ B = y \/ y R B ) <-> ( B R C \/ B = C \/ C R B ) ) ) |
10 |
9
|
imbi2d |
|- ( y = C -> ( ( R Or A -> ( B R y \/ B = y \/ y R B ) ) <-> ( R Or A -> ( B R C \/ B = C \/ C R B ) ) ) ) |
11 |
|
df-so |
|- ( R Or A <-> ( R Po A /\ A. x e. A A. y e. A ( x R y \/ x = y \/ y R x ) ) ) |
12 |
|
breq1 |
|- ( x = z -> ( x R y <-> z R y ) ) |
13 |
|
equequ1 |
|- ( x = z -> ( x = y <-> z = y ) ) |
14 |
|
breq2 |
|- ( x = z -> ( y R x <-> y R z ) ) |
15 |
12 13 14
|
3orbi123d |
|- ( x = z -> ( ( x R y \/ x = y \/ y R x ) <-> ( z R y \/ z = y \/ y R z ) ) ) |
16 |
15
|
ralbidv |
|- ( x = z -> ( A. y e. A ( x R y \/ x = y \/ y R x ) <-> A. y e. A ( z R y \/ z = y \/ y R z ) ) ) |
17 |
16
|
rspw |
|- ( A. x e. A A. y e. A ( x R y \/ x = y \/ y R x ) -> ( x e. A -> A. y e. A ( x R y \/ x = y \/ y R x ) ) ) |
18 |
|
breq2 |
|- ( y = z -> ( x R y <-> x R z ) ) |
19 |
|
equequ2 |
|- ( y = z -> ( x = y <-> x = z ) ) |
20 |
|
breq1 |
|- ( y = z -> ( y R x <-> z R x ) ) |
21 |
18 19 20
|
3orbi123d |
|- ( y = z -> ( ( x R y \/ x = y \/ y R x ) <-> ( x R z \/ x = z \/ z R x ) ) ) |
22 |
21
|
rspw |
|- ( A. y e. A ( x R y \/ x = y \/ y R x ) -> ( y e. A -> ( x R y \/ x = y \/ y R x ) ) ) |
23 |
17 22
|
syl6 |
|- ( A. x e. A A. y e. A ( x R y \/ x = y \/ y R x ) -> ( x e. A -> ( y e. A -> ( x R y \/ x = y \/ y R x ) ) ) ) |
24 |
23
|
impd |
|- ( A. x e. A A. y e. A ( x R y \/ x = y \/ y R x ) -> ( ( x e. A /\ y e. A ) -> ( x R y \/ x = y \/ y R x ) ) ) |
25 |
11 24
|
simplbiim |
|- ( R Or A -> ( ( x e. A /\ y e. A ) -> ( x R y \/ x = y \/ y R x ) ) ) |
26 |
25
|
com12 |
|- ( ( x e. A /\ y e. A ) -> ( R Or A -> ( x R y \/ x = y \/ y R x ) ) ) |
27 |
5 10 26
|
vtocl2ga |
|- ( ( B e. A /\ C e. A ) -> ( R Or A -> ( B R C \/ B = C \/ C R B ) ) ) |
28 |
27
|
impcom |
|- ( ( R Or A /\ ( B e. A /\ C e. A ) ) -> ( B R C \/ B = C \/ C R B ) ) |