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Theorem pwel 4847
 Description: Membership of a power class. Exercise 10 of [Enderton] p. 26. (Contributed by NM, 13-Jan-2007.)
Assertion
Ref Expression
pwel (𝐴𝐵 → 𝒫 𝐴 ∈ 𝒫 𝒫 𝐵)

Proof of Theorem pwel
StepHypRef Expression
1 elssuni 4403 . . 3 (𝐴𝐵𝐴 𝐵)
2 sspwb 4844 . . 3 (𝐴 𝐵 ↔ 𝒫 𝐴 ⊆ 𝒫 𝐵)
31, 2sylib 207 . 2 (𝐴𝐵 → 𝒫 𝐴 ⊆ 𝒫 𝐵)
4 pwexg 4776 . . 3 (𝐴𝐵 → 𝒫 𝐴 ∈ V)
5 elpwg 4116 . . 3 (𝒫 𝐴 ∈ V → (𝒫 𝐴 ∈ 𝒫 𝒫 𝐵 ↔ 𝒫 𝐴 ⊆ 𝒫 𝐵))
64, 5syl 17 . 2 (𝐴𝐵 → (𝒫 𝐴 ∈ 𝒫 𝒫 𝐵 ↔ 𝒫 𝐴 ⊆ 𝒫 𝐵))
73, 6mpbird 246 1 (𝐴𝐵 → 𝒫 𝐴 ∈ 𝒫 𝒫 𝐵)
 Colors of variables: wff setvar class Syntax hints:   → wi 4   ↔ wb 195   ∈ wcel 1977  Vcvv 3173   ⊆ wss 3540  𝒫 cpw 4108  ∪ cuni 4372 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1713  ax-4 1728  ax-5 1827  ax-6 1875  ax-7 1922  ax-9 1986  ax-10 2006  ax-11 2021  ax-12 2034  ax-13 2234  ax-ext 2590  ax-sep 4709  ax-nul 4717  ax-pow 4769  ax-pr 4833 This theorem depends on definitions:  df-bi 196  df-or 384  df-an 385  df-3an 1033  df-tru 1478  df-ex 1696  df-nf 1701  df-sb 1868  df-clab 2597  df-cleq 2603  df-clel 2606  df-nfc 2740  df-v 3175  df-dif 3543  df-un 3545  df-in 3547  df-ss 3554  df-nul 3875  df-pw 4110  df-sn 4126  df-pr 4128  df-uni 4373 This theorem is referenced by: (None)
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