Description: Lemma for ercpbl . (Contributed by Mario Carneiro, 24-Feb-2015) (Revised by AV, 12-Jul-2024)
Ref | Expression | ||
---|---|---|---|
Hypotheses | ercpbl.r | |- ( ph -> .~ Er V ) |
|
ercpbl.v | |- ( ph -> V e. W ) |
||
ercpbl.f | |- F = ( x e. V |-> [ x ] .~ ) |
||
ercpbllem.1 | |- ( ph -> A e. V ) |
||
Assertion | ercpbllem | |- ( ph -> ( ( F ` A ) = ( F ` B ) <-> A .~ B ) ) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | ercpbl.r | |- ( ph -> .~ Er V ) |
|
2 | ercpbl.v | |- ( ph -> V e. W ) |
|
3 | ercpbl.f | |- F = ( x e. V |-> [ x ] .~ ) |
|
4 | ercpbllem.1 | |- ( ph -> A e. V ) |
|
5 | 1 2 3 | divsfval | |- ( ph -> ( F ` A ) = [ A ] .~ ) |
6 | 1 2 3 | divsfval | |- ( ph -> ( F ` B ) = [ B ] .~ ) |
7 | 5 6 | eqeq12d | |- ( ph -> ( ( F ` A ) = ( F ` B ) <-> [ A ] .~ = [ B ] .~ ) ) |
8 | 1 4 | erth | |- ( ph -> ( A .~ B <-> [ A ] .~ = [ B ] .~ ) ) |
9 | 7 8 | bitr4d | |- ( ph -> ( ( F ` A ) = ( F ` B ) <-> A .~ B ) ) |