Metamath Proof Explorer


Theorem dmmptdff

Description: The domain of the mapping operation, deduction form. (Contributed by Glauco Siliprandi, 21-Dec-2024)

Ref Expression
Hypotheses dmmptdff.x
|- F/ x ph
dmmptdff.1
|- F/_ x B
dmmptdff.a
|- A = ( x e. B |-> C )
dmmptdff.c
|- ( ( ph /\ x e. B ) -> C e. V )
Assertion dmmptdff
|- ( ph -> dom A = B )

Proof

Step Hyp Ref Expression
1 dmmptdff.x
 |-  F/ x ph
2 dmmptdff.1
 |-  F/_ x B
3 dmmptdff.a
 |-  A = ( x e. B |-> C )
4 dmmptdff.c
 |-  ( ( ph /\ x e. B ) -> C e. V )
5 3 dmmpt
 |-  dom A = { x e. B | C e. _V }
6 4 elexd
 |-  ( ( ph /\ x e. B ) -> C e. _V )
7 1 6 ralrimia
 |-  ( ph -> A. x e. B C e. _V )
8 2 rabid2f
 |-  ( B = { x e. B | C e. _V } <-> A. x e. B C e. _V )
9 7 8 sylibr
 |-  ( ph -> B = { x e. B | C e. _V } )
10 5 9 eqtr4id
 |-  ( ph -> dom A = B )