Database
ZF (ZERMELO-FRAENKEL) SET THEORY
ZF Set Theory - start with the Axiom of Extensionality
Negated equality and membership
Negated equality
df-ne
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neii
Metamath Proof Explorer
Ascii
Structured
Definition
df-ne
Description:
Define inequality.
(Contributed by
NM
, 26-May-1993)
Ref
Expression
Assertion
df-ne
⊢
(
𝐴
≠
𝐵
↔ ¬
𝐴
=
𝐵
)
Detailed syntax breakdown
Step
Hyp
Ref
Expression
0
cA
⊢
𝐴
1
cB
⊢
𝐵
2
0
1
wne
⊢
𝐴
≠
𝐵
3
0
1
wceq
⊢
𝐴
=
𝐵
4
3
wn
⊢
¬
𝐴
=
𝐵
5
2
4
wb
⊢
(
𝐴
≠
𝐵
↔ ¬
𝐴
=
𝐵
)