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Theorem pweqb 4361
Description: Classes are equal if and only if their power classes are equal. Exercise 19 of [TakeutiZaring] p. 18. (Contributed by NM, 13-Oct-1996.)
Assertion
Ref Expression
pweqb  |-  ( A  =  B  <->  ~P A  =  ~P B )

Proof of Theorem pweqb
StepHypRef Expression
1 sspwb 4354 . . 3  |-  ( A 
C_  B  <->  ~P A  C_ 
~P B )
2 sspwb 4354 . . 3  |-  ( B 
C_  A  <->  ~P B  C_ 
~P A )
31, 2anbi12i 679 . 2  |-  ( ( A  C_  B  /\  B  C_  A )  <->  ( ~P A  C_  ~P B  /\  ~P B  C_  ~P A
) )
4 eqss 3306 . 2  |-  ( A  =  B  <->  ( A  C_  B  /\  B  C_  A ) )
5 eqss 3306 . 2  |-  ( ~P A  =  ~P B  <->  ( ~P A  C_  ~P B  /\  ~P B  C_  ~P A ) )
63, 4, 53bitr4i 269 1  |-  ( A  =  B  <->  ~P A  =  ~P B )
Colors of variables: wff set class
Syntax hints:    <-> wb 177    /\ wa 359    = wceq 1649    C_ wss 3263   ~Pcpw 3742
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-3 7  ax-mp 8  ax-gen 1552  ax-5 1563  ax-17 1623  ax-9 1661  ax-8 1682  ax-14 1721  ax-6 1736  ax-7 1741  ax-11 1753  ax-12 1939  ax-ext 2368  ax-sep 4271  ax-nul 4279  ax-pr 4344
This theorem depends on definitions:  df-bi 178  df-or 360  df-an 361  df-tru 1325  df-ex 1548  df-nf 1551  df-sb 1656  df-clab 2374  df-cleq 2380  df-clel 2383  df-nfc 2512  df-ne 2552  df-v 2901  df-dif 3266  df-un 3268  df-in 3270  df-ss 3277  df-nul 3572  df-pw 3744  df-sn 3763  df-pr 3764
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