Database
ZF (ZERMELO-FRAENKEL) SET THEORY
ZF Set Theory - start with the Axiom of Extensionality
Class form not-free predicate
nfcrd
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nfcriOLD
Metamath Proof Explorer
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Theorem
nfcrd
Description:
Consequence of the not-free predicate.
(Contributed by
Mario Carneiro
, 11-Aug-2016)
Ref
Expression
Hypothesis
nfcrd.1
⊢
φ
→
Ⅎ
_
x
A
Assertion
nfcrd
⊢
φ
→
Ⅎ
x
y
∈
A
Proof
Step
Hyp
Ref
Expression
1
nfcrd.1
⊢
φ
→
Ⅎ
_
x
A
2
nfcr
⊢
Ⅎ
_
x
A
→
Ⅎ
x
y
∈
A
3
1
2
syl
⊢
φ
→
Ⅎ
x
y
∈
A