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Theorem axpr 4671
Description: Unabbreviated version of the Axiom of Pairing of ZF set theory, derived as a theorem from the other axioms.

This theorem should not be referenced by any proof. Instead, use ax-pr 4672 below so that the uses of the Axiom of Pairing can be more easily identified. (Contributed by NM, 14-Nov-2006.) (New usage is discouraged.)

Assertion
Ref Expression
axpr  |-  E. z A. w ( ( w  =  x  \/  w  =  y )  ->  w  e.  z )
Distinct variable groups:    x, z, w    y, z, w

Proof of Theorem axpr
StepHypRef Expression
1 zfpair 4670 . . 3  |-  { x ,  y }  e.  _V
21isseti 3099 . 2  |-  E. z 
z  =  { x ,  y }
3 dfcleq 2434 . . 3  |-  ( z  =  { x ,  y }  <->  A. w
( w  e.  z  <-> 
w  e.  { x ,  y } ) )
4 vex 3096 . . . . . . 7  |-  w  e. 
_V
54elpr 4028 . . . . . 6  |-  ( w  e.  { x ,  y }  <->  ( w  =  x  \/  w  =  y ) )
65bibi2i 313 . . . . 5  |-  ( ( w  e.  z  <->  w  e.  { x ,  y } )  <->  ( w  e.  z  <->  ( w  =  x  \/  w  =  y ) ) )
7 bi2 198 . . . . 5  |-  ( ( w  e.  z  <->  ( w  =  x  \/  w  =  y ) )  ->  ( ( w  =  x  \/  w  =  y )  ->  w  e.  z )
)
86, 7sylbi 195 . . . 4  |-  ( ( w  e.  z  <->  w  e.  { x ,  y } )  ->  ( (
w  =  x  \/  w  =  y )  ->  w  e.  z ) )
98alimi 1618 . . 3  |-  ( A. w ( w  e.  z  <->  w  e.  { x ,  y } )  ->  A. w ( ( w  =  x  \/  w  =  y )  ->  w  e.  z ) )
103, 9sylbi 195 . 2  |-  ( z  =  { x ,  y }  ->  A. w
( ( w  =  x  \/  w  =  y )  ->  w  e.  z ) )
112, 10eximii 1643 1  |-  E. z A. w ( ( w  =  x  \/  w  =  y )  ->  w  e.  z )
Colors of variables: wff setvar class
Syntax hints:    -> wi 4    <-> wb 184    \/ wo 368   A.wal 1379    = wceq 1381   E.wex 1597    e. wcel 1802   {cpr 4012
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1603  ax-4 1616  ax-5 1689  ax-6 1732  ax-7 1774  ax-9 1806  ax-10 1821  ax-11 1826  ax-12 1838  ax-13 1983  ax-ext 2419  ax-rep 4544  ax-sep 4554  ax-nul 4562  ax-pow 4611
This theorem depends on definitions:  df-bi 185  df-or 370  df-an 371  df-3an 974  df-tru 1384  df-ex 1598  df-nf 1602  df-sb 1725  df-clab 2427  df-cleq 2433  df-clel 2436  df-nfc 2591  df-ne 2638  df-v 3095  df-dif 3461  df-un 3463  df-in 3465  df-ss 3472  df-nul 3768  df-pw 3995  df-sn 4011  df-pr 4013
This theorem is referenced by: (None)
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