Database
ZF (ZERMELO-FRAENKEL) SET THEORY
ZF Set Theory - add the Axiom of Power Sets
Relations
elima3
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nfima
Metamath Proof Explorer
Ascii
Unicode
Theorem
elima3
Description:
Membership in an image. Theorem 34 of
Suppes
p. 65.
(Contributed by
NM
, 14-Aug-1994)
Ref
Expression
Hypothesis
elima.1
⊢
A
∈
V
Assertion
elima3
⊢
A
∈
B
C
↔
∃
x
x
∈
C
∧
x
A
∈
B
Proof
Step
Hyp
Ref
Expression
1
elima.1
⊢
A
∈
V
2
1
elima2
⊢
A
∈
B
C
↔
∃
x
x
∈
C
∧
x
B
A
3
df-br
⊢
x
B
A
↔
x
A
∈
B
4
3
anbi2i
⊢
x
∈
C
∧
x
B
A
↔
x
∈
C
∧
x
A
∈
B
5
4
exbii
⊢
∃
x
x
∈
C
∧
x
B
A
↔
∃
x
x
∈
C
∧
x
A
∈
B
6
2
5
bitri
⊢
A
∈
B
C
↔
∃
x
x
∈
C
∧
x
A
∈
B