Database
ZF (ZERMELO-FRAENKEL) SET THEORY
ZF Set Theory - start with the Axiom of Extensionality
Proper substitution of classes for sets
sbcied
Metamath Proof Explorer
Description: Conversion of implicit substitution to explicit class substitution,
deduction form. (Contributed by NM , 13-Dec-2014) Avoid ax-10 ,
ax-12 . (Revised by Gino Giotto , 12-Oct-2024)
Ref
Expression
Hypotheses
sbcied.1
|- ( ph -> A e. V )
sbcied.2
|- ( ( ph /\ x = A ) -> ( ps <-> ch ) )
Assertion
sbcied
|- ( ph -> ( [. A / x ]. ps <-> ch ) )
Proof
Step
Hyp
Ref
Expression
1
sbcied.1
|- ( ph -> A e. V )
2
sbcied.2
|- ( ( ph /\ x = A ) -> ( ps <-> ch ) )
3
df-sbc
|- ( [. A / x ]. ps <-> A e. { x | ps } )
4
1 2
elabd3
|- ( ph -> ( A e. { x | ps } <-> ch ) )
5
3 4
syl5bb
|- ( ph -> ( [. A / x ]. ps <-> ch ) )