Database
ZF (ZERMELO-FRAENKEL) SET THEORY
ZF Set Theory - add the Axiom of Replacement
Theorems requiring empty set existence
0elpw
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pwne0
Metamath Proof Explorer
Ascii
Structured
Theorem
0elpw
Description:
Every power class contains the empty set.
(Contributed by
NM
, 25-Oct-2007)
Ref
Expression
Assertion
0elpw
⊢
∅ ∈ 𝒫
𝐴
Proof
Step
Hyp
Ref
Expression
1
0ss
⊢
∅ ⊆
𝐴
2
0ex
⊢
∅ ∈ V
3
2
elpw
⊢
( ∅ ∈ 𝒫
𝐴
↔ ∅ ⊆
𝐴
)
4
1
3
mpbir
⊢
∅ ∈ 𝒫
𝐴