Database
ZF (ZERMELO-FRAENKEL) SET THEORY
ZF Set Theory - add the Axiom of Union
Weak dominance
0wdom
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fowdom
Metamath Proof Explorer
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Theorem
0wdom
Description:
Any set weakly dominates the empty set.
(Contributed by
Stefan O'Rear
, 11-Feb-2015)
Ref
Expression
Assertion
0wdom
⊢
X
∈
V
→
∅
≼
*
X
Proof
Step
Hyp
Ref
Expression
1
eqid
⊢
∅
=
∅
2
1
orci
⊢
∅
=
∅
∨
∃
z
z
:
X
⟶
onto
∅
3
brwdom
⊢
X
∈
V
→
∅
≼
*
X
↔
∅
=
∅
∨
∃
z
z
:
X
⟶
onto
∅
4
2
3
mpbiri
⊢
X
∈
V
→
∅
≼
*
X