Database
ZF (ZERMELO-FRAENKEL) SET THEORY
ZF Set Theory - start with the Axiom of Extensionality
Negated equality and membership
Negated equality
neii
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neir
Metamath Proof Explorer
Ascii
Unicode
Theorem
neii
Description:
Inference associated with
df-ne
.
(Contributed by
BJ
, 7-Jul-2018)
Ref
Expression
Hypothesis
neii.1
⊢
A
≠
B
Assertion
neii
⊢
¬
A
=
B
Proof
Step
Hyp
Ref
Expression
1
neii.1
⊢
A
≠
B
2
df-ne
⊢
A
≠
B
↔
¬
A
=
B
3
1
2
mpbi
⊢
¬
A
=
B