Metamath Proof Explorer


Theorem bj-elpwg

Description: If the intersection of two classes is a set, then inclusion among these classes is equivalent to membership in the powerclass. Common generalization of elpwg and elpw2g (the latter of which could be proved from it). (Contributed by BJ, 31-Dec-2023)

Ref Expression
Assertion bj-elpwg ( ( 𝐴𝐵 ) ∈ 𝑉 → ( 𝐴 ∈ 𝒫 𝐵𝐴𝐵 ) )

Proof

Step Hyp Ref Expression
1 elpwi ( 𝐴 ∈ 𝒫 𝐵𝐴𝐵 )
2 ssidd ( 𝐴𝐵𝐴𝐴 )
3 id ( 𝐴𝐵𝐴𝐵 )
4 2 3 ssind ( 𝐴𝐵𝐴 ⊆ ( 𝐴𝐵 ) )
5 ssexg ( ( 𝐴 ⊆ ( 𝐴𝐵 ) ∧ ( 𝐴𝐵 ) ∈ 𝑉 ) → 𝐴 ∈ V )
6 4 5 sylan ( ( 𝐴𝐵 ∧ ( 𝐴𝐵 ) ∈ 𝑉 ) → 𝐴 ∈ V )
7 elpwg ( 𝐴 ∈ V → ( 𝐴 ∈ 𝒫 𝐵𝐴𝐵 ) )
8 7 biimparc ( ( 𝐴𝐵𝐴 ∈ V ) → 𝐴 ∈ 𝒫 𝐵 )
9 6 8 syldan ( ( 𝐴𝐵 ∧ ( 𝐴𝐵 ) ∈ 𝑉 ) → 𝐴 ∈ 𝒫 𝐵 )
10 9 expcom ( ( 𝐴𝐵 ) ∈ 𝑉 → ( 𝐴𝐵𝐴 ∈ 𝒫 𝐵 ) )
11 1 10 impbid2 ( ( 𝐴𝐵 ) ∈ 𝑉 → ( 𝐴 ∈ 𝒫 𝐵𝐴𝐵 ) )