Database
ZF (ZERMELO-FRAENKEL) SET THEORY
ZF Set Theory - add the Axiom of Union
Equinumerosity
reldom
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relsdom
Metamath Proof Explorer
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Unicode
Theorem
reldom
Description:
Dominance is a relation.
(Contributed by
NM
, 28-Mar-1998)
Ref
Expression
Assertion
reldom
⊢
Rel
⁡
≼
Proof
Step
Hyp
Ref
Expression
1
df-dom
⊢
≼
=
x
y
|
∃
f
f
:
x
⟶
1-1
y
2
1
relopabiv
⊢
Rel
⁡
≼