Database
ZF (ZERMELO-FRAENKEL) SET THEORY
ZF Set Theory - start with the Axiom of Extensionality
The universal class
spcegv
Metamath Proof Explorer
Description: Existential specialization, using implicit substitution. (Contributed by NM , 14-Aug-1994) Avoid ax-10 , ax-11 . (Revised by Wolf
Lammen , 25-Aug-2023)
Ref
Expression
Hypothesis
spcgv.1
|- ( x = A -> ( ph <-> ps ) )
Assertion
spcegv
|- ( A e. V -> ( ps -> E. x ph ) )
Proof
Step
Hyp
Ref
Expression
1
spcgv.1
|- ( x = A -> ( ph <-> ps ) )
2
elisset
|- ( A e. V -> E. x x = A )
3
1
biimprcd
|- ( ps -> ( x = A -> ph ) )
4
3
eximdv
|- ( ps -> ( E. x x = A -> E. x ph ) )
5
2 4
syl5com
|- ( A e. V -> ( ps -> E. x ph ) )