Step |
Hyp |
Ref |
Expression |
1 |
|
mdsym.1 |
|- A e. CH |
2 |
|
mdsym.2 |
|- B e. CH |
3 |
2
|
choccli |
|- ( _|_ ` B ) e. CH |
4 |
1
|
choccli |
|- ( _|_ ` A ) e. CH |
5 |
|
eqid |
|- ( ( _|_ ` B ) vH x ) = ( ( _|_ ` B ) vH x ) |
6 |
3 4 5
|
mdsymlem8 |
|- ( ( ( _|_ ` B ) =/= 0H /\ ( _|_ ` A ) =/= 0H ) -> ( ( _|_ ` A ) MH* ( _|_ ` B ) <-> ( _|_ ` B ) MH* ( _|_ ` A ) ) ) |
7 |
|
mddmd |
|- ( ( A e. CH /\ B e. CH ) -> ( A MH B <-> ( _|_ ` A ) MH* ( _|_ ` B ) ) ) |
8 |
1 2 7
|
mp2an |
|- ( A MH B <-> ( _|_ ` A ) MH* ( _|_ ` B ) ) |
9 |
|
mddmd |
|- ( ( B e. CH /\ A e. CH ) -> ( B MH A <-> ( _|_ ` B ) MH* ( _|_ ` A ) ) ) |
10 |
2 1 9
|
mp2an |
|- ( B MH A <-> ( _|_ ` B ) MH* ( _|_ ` A ) ) |
11 |
6 8 10
|
3bitr4g |
|- ( ( ( _|_ ` B ) =/= 0H /\ ( _|_ ` A ) =/= 0H ) -> ( A MH B <-> B MH A ) ) |
12 |
1
|
chssii |
|- A C_ ~H |
13 |
|
fveq2 |
|- ( ( _|_ ` B ) = 0H -> ( _|_ ` ( _|_ ` B ) ) = ( _|_ ` 0H ) ) |
14 |
2
|
pjococi |
|- ( _|_ ` ( _|_ ` B ) ) = B |
15 |
|
choc0 |
|- ( _|_ ` 0H ) = ~H |
16 |
13 14 15
|
3eqtr3g |
|- ( ( _|_ ` B ) = 0H -> B = ~H ) |
17 |
12 16
|
sseqtrrid |
|- ( ( _|_ ` B ) = 0H -> A C_ B ) |
18 |
|
ssmd1 |
|- ( ( A e. CH /\ B e. CH /\ A C_ B ) -> A MH B ) |
19 |
1 2 18
|
mp3an12 |
|- ( A C_ B -> A MH B ) |
20 |
|
ssmd2 |
|- ( ( A e. CH /\ B e. CH /\ A C_ B ) -> B MH A ) |
21 |
1 2 20
|
mp3an12 |
|- ( A C_ B -> B MH A ) |
22 |
19 21
|
jca |
|- ( A C_ B -> ( A MH B /\ B MH A ) ) |
23 |
|
pm5.1 |
|- ( ( A MH B /\ B MH A ) -> ( A MH B <-> B MH A ) ) |
24 |
17 22 23
|
3syl |
|- ( ( _|_ ` B ) = 0H -> ( A MH B <-> B MH A ) ) |
25 |
2
|
chssii |
|- B C_ ~H |
26 |
|
fveq2 |
|- ( ( _|_ ` A ) = 0H -> ( _|_ ` ( _|_ ` A ) ) = ( _|_ ` 0H ) ) |
27 |
1
|
pjococi |
|- ( _|_ ` ( _|_ ` A ) ) = A |
28 |
26 27 15
|
3eqtr3g |
|- ( ( _|_ ` A ) = 0H -> A = ~H ) |
29 |
25 28
|
sseqtrrid |
|- ( ( _|_ ` A ) = 0H -> B C_ A ) |
30 |
|
ssmd2 |
|- ( ( B e. CH /\ A e. CH /\ B C_ A ) -> A MH B ) |
31 |
2 1 30
|
mp3an12 |
|- ( B C_ A -> A MH B ) |
32 |
|
ssmd1 |
|- ( ( B e. CH /\ A e. CH /\ B C_ A ) -> B MH A ) |
33 |
2 1 32
|
mp3an12 |
|- ( B C_ A -> B MH A ) |
34 |
31 33
|
jca |
|- ( B C_ A -> ( A MH B /\ B MH A ) ) |
35 |
29 34 23
|
3syl |
|- ( ( _|_ ` A ) = 0H -> ( A MH B <-> B MH A ) ) |
36 |
11 24 35
|
pm2.61iine |
|- ( A MH B <-> B MH A ) |