Database
ZF (ZERMELO-FRAENKEL) SET THEORY
ZF Set Theory - start with the Axiom of Extensionality
Proper substitution of classes for sets
spesbcd
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sbcth2
Metamath Proof Explorer
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Unicode
Theorem
spesbcd
Description:
form of
spsbc
.
(Contributed by
Mario Carneiro
, 9-Feb-2017)
Ref
Expression
Hypothesis
spesbcd.1
⊢
φ
→
[
˙
A
/
x
]
˙
ψ
Assertion
spesbcd
⊢
φ
→
∃
x
ψ
Proof
Step
Hyp
Ref
Expression
1
spesbcd.1
⊢
φ
→
[
˙
A
/
x
]
˙
ψ
2
spesbc
⊢
[
˙
A
/
x
]
˙
ψ
→
∃
x
ψ
3
1
2
syl
⊢
φ
→
∃
x
ψ