Step |
Hyp |
Ref |
Expression |
1 |
|
sstr2 |
|- ( A C_ B -> ( B C_ x -> A C_ x ) ) |
2 |
1
|
ralrimivw |
|- ( A C_ B -> A. x e. SH ( B C_ x -> A C_ x ) ) |
3 |
|
ss2rab |
|- ( { x e. SH | B C_ x } C_ { x e. SH | A C_ x } <-> A. x e. SH ( B C_ x -> A C_ x ) ) |
4 |
2 3
|
sylibr |
|- ( A C_ B -> { x e. SH | B C_ x } C_ { x e. SH | A C_ x } ) |
5 |
|
intss |
|- ( { x e. SH | B C_ x } C_ { x e. SH | A C_ x } -> |^| { x e. SH | A C_ x } C_ |^| { x e. SH | B C_ x } ) |
6 |
4 5
|
syl |
|- ( A C_ B -> |^| { x e. SH | A C_ x } C_ |^| { x e. SH | B C_ x } ) |
7 |
6
|
adantl |
|- ( ( B C_ ~H /\ A C_ B ) -> |^| { x e. SH | A C_ x } C_ |^| { x e. SH | B C_ x } ) |
8 |
|
sstr |
|- ( ( A C_ B /\ B C_ ~H ) -> A C_ ~H ) |
9 |
8
|
ancoms |
|- ( ( B C_ ~H /\ A C_ B ) -> A C_ ~H ) |
10 |
|
spanval |
|- ( A C_ ~H -> ( span ` A ) = |^| { x e. SH | A C_ x } ) |
11 |
9 10
|
syl |
|- ( ( B C_ ~H /\ A C_ B ) -> ( span ` A ) = |^| { x e. SH | A C_ x } ) |
12 |
|
spanval |
|- ( B C_ ~H -> ( span ` B ) = |^| { x e. SH | B C_ x } ) |
13 |
12
|
adantr |
|- ( ( B C_ ~H /\ A C_ B ) -> ( span ` B ) = |^| { x e. SH | B C_ x } ) |
14 |
7 11 13
|
3sstr4d |
|- ( ( B C_ ~H /\ A C_ B ) -> ( span ` A ) C_ ( span ` B ) ) |