Metamath Proof Explorer


Theorem ercpbllem

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 ) )

Proof

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 ) )