Database
ZF (ZERMELO-FRAENKEL) SET THEORY
ZF Set Theory - start with the Axiom of Extensionality
Power classes
sspwd
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pweq
Metamath Proof Explorer
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Unicode
Theorem
sspwd
Description:
The powerclass preserves inclusion (deduction form).
(Contributed by
BJ
, 13-Apr-2024)
Ref
Expression
Hypothesis
sspwd.1
⊢
φ
→
A
⊆
B
Assertion
sspwd
⊢
φ
→
𝒫
A
⊆
𝒫
B
Proof
Step
Hyp
Ref
Expression
1
sspwd.1
⊢
φ
→
A
⊆
B
2
sspw
⊢
A
⊆
B
→
𝒫
A
⊆
𝒫
B
3
1
2
syl
⊢
φ
→
𝒫
A
⊆
𝒫
B