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wl-ax11-lem7
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wl-ax11-lem8
Metamath Proof Explorer
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Theorem
wl-ax11-lem7
Description:
Lemma.
(Contributed by
Wolf Lammen
, 30-Jun-2019)
Ref
Expression
Assertion
wl-ax11-lem7
⊢
∀
x
¬
∀
x
x
=
y
∧
φ
↔
¬
∀
x
x
=
y
∧
∀
x
φ
Proof
Step
Hyp
Ref
Expression
1
nfna1
⊢
Ⅎ
x
¬
∀
x
x
=
y
2
1
19.28
⊢
∀
x
¬
∀
x
x
=
y
∧
φ
↔
¬
∀
x
x
=
y
∧
∀
x
φ