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Theorem dfac11 26830
Description: The right-hand side of this theorem (compare with ac4 8289), sometimes known as the "axiom of multiple choice", is a choice equivalent. Curiously, this statement cannot be proved without ax-reg 7494, despite not mentioning the cumulative hierarchy in any way as most consequences of regularity do.

This is definition (MC) of [Schechter] p. 141. EDITORIAL: the proof is not original with me of course but I lost my reference sometime after writing it.

A multiple choice function allows any total order to be extended to a choice function, which in turn defines a well-ordering. Since a well ordering on a set defines a simple ordering of the power set, this allows the trivial well-ordering of the empty set to be transfinitely bootstrapped up the cumulative hierarchy to any desired level. (Contributed by Stefan O'Rear, 20-Jan-2015.) (Revised by Stefan O'Rear, 1-Jun-2015.)

Assertion
Ref Expression
dfac11  |-  (CHOICE  <->  A. x E. f A. z  e.  x  ( z  =/=  (/)  ->  ( f `  z )  e.  ( ( ~P z  i^i 
Fin )  \  { (/)
} ) ) )
Distinct variable group:    x, z, f

Proof of Theorem dfac11
Dummy variables  a 
b  c  d are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 dfac3 7936 . . 3  |-  (CHOICE  <->  A. a E. c A. d  e.  a  ( d  =/=  (/)  ->  ( c `  d )  e.  d ) )
2 raleq 2848 . . . . . 6  |-  ( a  =  x  ->  ( A. d  e.  a 
( d  =/=  (/)  ->  (
c `  d )  e.  d )  <->  A. d  e.  x  ( d  =/=  (/)  ->  ( c `  d )  e.  d ) ) )
32exbidv 1633 . . . . 5  |-  ( a  =  x  ->  ( E. c A. d  e.  a  ( d  =/=  (/)  ->  ( c `  d )  e.  d )  <->  E. c A. d  e.  x  ( d  =/=  (/)  ->  ( c `  d )  e.  d ) ) )
43cbvalv 2037 . . . 4  |-  ( A. a E. c A. d  e.  a  ( d  =/=  (/)  ->  ( c `  d )  e.  d )  <->  A. x E. c A. d  e.  x  ( d  =/=  (/)  ->  (
c `  d )  e.  d ) )
5 neeq1 2559 . . . . . . . . . 10  |-  ( d  =  z  ->  (
d  =/=  (/)  <->  z  =/=  (/) ) )
6 fveq2 5669 . . . . . . . . . . 11  |-  ( d  =  z  ->  (
c `  d )  =  ( c `  z ) )
7 id 20 . . . . . . . . . . 11  |-  ( d  =  z  ->  d  =  z )
86, 7eleq12d 2456 . . . . . . . . . 10  |-  ( d  =  z  ->  (
( c `  d
)  e.  d  <->  ( c `  z )  e.  z ) )
95, 8imbi12d 312 . . . . . . . . 9  |-  ( d  =  z  ->  (
( d  =/=  (/)  ->  (
c `  d )  e.  d )  <->  ( z  =/=  (/)  ->  ( c `  z )  e.  z ) ) )
109cbvralv 2876 . . . . . . . 8  |-  ( A. d  e.  x  (
d  =/=  (/)  ->  (
c `  d )  e.  d )  <->  A. z  e.  x  ( z  =/=  (/)  ->  ( c `  z )  e.  z ) )
11 fveq2 5669 . . . . . . . . . . . . . . 15  |-  ( b  =  z  ->  (
c `  b )  =  ( c `  z ) )
1211sneqd 3771 . . . . . . . . . . . . . 14  |-  ( b  =  z  ->  { ( c `  b ) }  =  { ( c `  z ) } )
13 eqid 2388 . . . . . . . . . . . . . 14  |-  ( b  e.  x  |->  { ( c `  b ) } )  =  ( b  e.  x  |->  { ( c `  b
) } )
14 snex 4347 . . . . . . . . . . . . . 14  |-  { ( c `  z ) }  e.  _V
1512, 13, 14fvmpt 5746 . . . . . . . . . . . . 13  |-  ( z  e.  x  ->  (
( b  e.  x  |->  { ( c `  b ) } ) `
 z )  =  { ( c `  z ) } )
16153ad2ant1 978 . . . . . . . . . . . 12  |-  ( ( z  e.  x  /\  z  =/=  (/)  /\  ( c `
 z )  e.  z )  ->  (
( b  e.  x  |->  { ( c `  b ) } ) `
 z )  =  { ( c `  z ) } )
17 simp3 959 . . . . . . . . . . . . . . . 16  |-  ( ( z  e.  x  /\  z  =/=  (/)  /\  ( c `
 z )  e.  z )  ->  (
c `  z )  e.  z )
1817snssd 3887 . . . . . . . . . . . . . . 15  |-  ( ( z  e.  x  /\  z  =/=  (/)  /\  ( c `
 z )  e.  z )  ->  { ( c `  z ) }  C_  z )
1914elpw 3749 . . . . . . . . . . . . . . 15  |-  ( { ( c `  z
) }  e.  ~P z 
<->  { ( c `  z ) }  C_  z )
2018, 19sylibr 204 . . . . . . . . . . . . . 14  |-  ( ( z  e.  x  /\  z  =/=  (/)  /\  ( c `
 z )  e.  z )  ->  { ( c `  z ) }  e.  ~P z
)
21 snfi 7124 . . . . . . . . . . . . . . 15  |-  { ( c `  z ) }  e.  Fin
2221a1i 11 . . . . . . . . . . . . . 14  |-  ( ( z  e.  x  /\  z  =/=  (/)  /\  ( c `
 z )  e.  z )  ->  { ( c `  z ) }  e.  Fin )
23 elin 3474 . . . . . . . . . . . . . 14  |-  ( { ( c `  z
) }  e.  ( ~P z  i^i  Fin ) 
<->  ( { ( c `
 z ) }  e.  ~P z  /\  { ( c `  z
) }  e.  Fin ) )
2420, 22, 23sylanbrc 646 . . . . . . . . . . . . 13  |-  ( ( z  e.  x  /\  z  =/=  (/)  /\  ( c `
 z )  e.  z )  ->  { ( c `  z ) }  e.  ( ~P z  i^i  Fin )
)
25 fvex 5683 . . . . . . . . . . . . . . 15  |-  ( c `
 z )  e. 
_V
2625snnz 3866 . . . . . . . . . . . . . 14  |-  { ( c `  z ) }  =/=  (/)
2726a1i 11 . . . . . . . . . . . . 13  |-  ( ( z  e.  x  /\  z  =/=  (/)  /\  ( c `
 z )  e.  z )  ->  { ( c `  z ) }  =/=  (/) )
28 eldifsn 3871 . . . . . . . . . . . . 13  |-  ( { ( c `  z
) }  e.  ( ( ~P z  i^i 
Fin )  \  { (/)
} )  <->  ( {
( c `  z
) }  e.  ( ~P z  i^i  Fin )  /\  { ( c `
 z ) }  =/=  (/) ) )
2924, 27, 28sylanbrc 646 . . . . . . . . . . . 12  |-  ( ( z  e.  x  /\  z  =/=  (/)  /\  ( c `
 z )  e.  z )  ->  { ( c `  z ) }  e.  ( ( ~P z  i^i  Fin )  \  { (/) } ) )
3016, 29eqeltrd 2462 . . . . . . . . . . 11  |-  ( ( z  e.  x  /\  z  =/=  (/)  /\  ( c `
 z )  e.  z )  ->  (
( b  e.  x  |->  { ( c `  b ) } ) `
 z )  e.  ( ( ~P z  i^i  Fin )  \  { (/)
} ) )
31303exp 1152 . . . . . . . . . 10  |-  ( z  e.  x  ->  (
z  =/=  (/)  ->  (
( c `  z
)  e.  z  -> 
( ( b  e.  x  |->  { ( c `
 b ) } ) `  z )  e.  ( ( ~P z  i^i  Fin )  \  { (/) } ) ) ) )
3231a2d 24 . . . . . . . . 9  |-  ( z  e.  x  ->  (
( z  =/=  (/)  ->  (
c `  z )  e.  z )  ->  (
z  =/=  (/)  ->  (
( b  e.  x  |->  { ( c `  b ) } ) `
 z )  e.  ( ( ~P z  i^i  Fin )  \  { (/)
} ) ) ) )
3332ralimia 2723 . . . . . . . 8  |-  ( A. z  e.  x  (
z  =/=  (/)  ->  (
c `  z )  e.  z )  ->  A. z  e.  x  ( z  =/=  (/)  ->  ( (
b  e.  x  |->  { ( c `  b
) } ) `  z )  e.  ( ( ~P z  i^i 
Fin )  \  { (/)
} ) ) )
3410, 33sylbi 188 . . . . . . 7  |-  ( A. d  e.  x  (
d  =/=  (/)  ->  (
c `  d )  e.  d )  ->  A. z  e.  x  ( z  =/=  (/)  ->  ( (
b  e.  x  |->  { ( c `  b
) } ) `  z )  e.  ( ( ~P z  i^i 
Fin )  \  { (/)
} ) ) )
35 vex 2903 . . . . . . . . 9  |-  x  e. 
_V
3635mptex 5906 . . . . . . . 8  |-  ( b  e.  x  |->  { ( c `  b ) } )  e.  _V
37 fveq1 5668 . . . . . . . . . . 11  |-  ( f  =  ( b  e.  x  |->  { ( c `
 b ) } )  ->  ( f `  z )  =  ( ( b  e.  x  |->  { ( c `  b ) } ) `
 z ) )
3837eleq1d 2454 . . . . . . . . . 10  |-  ( f  =  ( b  e.  x  |->  { ( c `
 b ) } )  ->  ( (
f `  z )  e.  ( ( ~P z  i^i  Fin )  \  { (/)
} )  <->  ( (
b  e.  x  |->  { ( c `  b
) } ) `  z )  e.  ( ( ~P z  i^i 
Fin )  \  { (/)
} ) ) )
3938imbi2d 308 . . . . . . . . 9  |-  ( f  =  ( b  e.  x  |->  { ( c `
 b ) } )  ->  ( (
z  =/=  (/)  ->  (
f `  z )  e.  ( ( ~P z  i^i  Fin )  \  { (/)
} ) )  <->  ( z  =/=  (/)  ->  ( (
b  e.  x  |->  { ( c `  b
) } ) `  z )  e.  ( ( ~P z  i^i 
Fin )  \  { (/)
} ) ) ) )
4039ralbidv 2670 . . . . . . . 8  |-  ( f  =  ( b  e.  x  |->  { ( c `
 b ) } )  ->  ( A. z  e.  x  (
z  =/=  (/)  ->  (
f `  z )  e.  ( ( ~P z  i^i  Fin )  \  { (/)
} ) )  <->  A. z  e.  x  ( z  =/=  (/)  ->  ( (
b  e.  x  |->  { ( c `  b
) } ) `  z )  e.  ( ( ~P z  i^i 
Fin )  \  { (/)
} ) ) ) )
4136, 40spcev 2987 . . . . . . 7  |-  ( A. z  e.  x  (
z  =/=  (/)  ->  (
( b  e.  x  |->  { ( c `  b ) } ) `
 z )  e.  ( ( ~P z  i^i  Fin )  \  { (/)
} ) )  ->  E. f A. z  e.  x  ( z  =/=  (/)  ->  ( f `  z )  e.  ( ( ~P z  i^i 
Fin )  \  { (/)
} ) ) )
4234, 41syl 16 . . . . . 6  |-  ( A. d  e.  x  (
d  =/=  (/)  ->  (
c `  d )  e.  d )  ->  E. f A. z  e.  x  ( z  =/=  (/)  ->  (
f `  z )  e.  ( ( ~P z  i^i  Fin )  \  { (/)
} ) ) )
4342exlimiv 1641 . . . . 5  |-  ( E. c A. d  e.  x  ( d  =/=  (/)  ->  ( c `  d )  e.  d )  ->  E. f A. z  e.  x  ( z  =/=  (/)  ->  (
f `  z )  e.  ( ( ~P z  i^i  Fin )  \  { (/)
} ) ) )
4443alimi 1565 . . . 4  |-  ( A. x E. c A. d  e.  x  ( d  =/=  (/)  ->  ( c `  d )  e.  d )  ->  A. x E. f A. z  e.  x  ( z  =/=  (/)  ->  ( f `  z )  e.  ( ( ~P z  i^i 
Fin )  \  { (/)
} ) ) )
454, 44sylbi 188 . . 3  |-  ( A. a E. c A. d  e.  a  ( d  =/=  (/)  ->  ( c `  d )  e.  d )  ->  A. x E. f A. z  e.  x  ( z  =/=  (/)  ->  ( f `  z )  e.  ( ( ~P z  i^i 
Fin )  \  { (/)
} ) ) )
461, 45sylbi 188 . 2  |-  (CHOICE  ->  A. x E. f A. z  e.  x  ( z  =/=  (/)  ->  ( f `  z )  e.  ( ( ~P z  i^i 
Fin )  \  { (/)
} ) ) )
47 fvex 5683 . . . . . . 7  |-  ( R1
`  ( rank `  a
) )  e.  _V
4847pwex 4324 . . . . . 6  |-  ~P ( R1 `  ( rank `  a
) )  e.  _V
49 raleq 2848 . . . . . . 7  |-  ( x  =  ~P ( R1
`  ( rank `  a
) )  ->  ( A. z  e.  x  ( z  =/=  (/)  ->  (
f `  z )  e.  ( ( ~P z  i^i  Fin )  \  { (/)
} ) )  <->  A. z  e.  ~P  ( R1 `  ( rank `  a )
) ( z  =/=  (/)  ->  ( f `  z )  e.  ( ( ~P z  i^i 
Fin )  \  { (/)
} ) ) ) )
5049exbidv 1633 . . . . . 6  |-  ( x  =  ~P ( R1
`  ( rank `  a
) )  ->  ( E. f A. z  e.  x  ( z  =/=  (/)  ->  ( f `  z )  e.  ( ( ~P z  i^i 
Fin )  \  { (/)
} ) )  <->  E. f A. z  e.  ~P  ( R1 `  ( rank `  a ) ) ( z  =/=  (/)  ->  (
f `  z )  e.  ( ( ~P z  i^i  Fin )  \  { (/)
} ) ) ) )
5148, 50spcv 2986 . . . . 5  |-  ( A. x E. f A. z  e.  x  ( z  =/=  (/)  ->  ( f `  z )  e.  ( ( ~P z  i^i 
Fin )  \  { (/)
} ) )  ->  E. f A. z  e. 
~P  ( R1 `  ( rank `  a )
) ( z  =/=  (/)  ->  ( f `  z )  e.  ( ( ~P z  i^i 
Fin )  \  { (/)
} ) ) )
52 rankon 7655 . . . . . . . 8  |-  ( rank `  a )  e.  On
5352a1i 11 . . . . . . 7  |-  ( A. z  e.  ~P  ( R1 `  ( rank `  a
) ) ( z  =/=  (/)  ->  ( f `  z )  e.  ( ( ~P z  i^i 
Fin )  \  { (/)
} ) )  -> 
( rank `  a )  e.  On )
54 id 20 . . . . . . 7  |-  ( A. z  e.  ~P  ( R1 `  ( rank `  a
) ) ( z  =/=  (/)  ->  ( f `  z )  e.  ( ( ~P z  i^i 
Fin )  \  { (/)
} ) )  ->  A. z  e.  ~P  ( R1 `  ( rank `  a ) ) ( z  =/=  (/)  ->  (
f `  z )  e.  ( ( ~P z  i^i  Fin )  \  { (/)
} ) ) )
5553, 54aomclem8 26829 . . . . . 6  |-  ( A. z  e.  ~P  ( R1 `  ( rank `  a
) ) ( z  =/=  (/)  ->  ( f `  z )  e.  ( ( ~P z  i^i 
Fin )  \  { (/)
} ) )  ->  E. b  b  We  ( R1 `  ( rank `  a ) ) )
5655exlimiv 1641 . . . . 5  |-  ( E. f A. z  e. 
~P  ( R1 `  ( rank `  a )
) ( z  =/=  (/)  ->  ( f `  z )  e.  ( ( ~P z  i^i 
Fin )  \  { (/)
} ) )  ->  E. b  b  We  ( R1 `  ( rank `  a ) ) )
57 vex 2903 . . . . . 6  |-  a  e. 
_V
58 r1rankid 7719 . . . . . 6  |-  ( a  e.  _V  ->  a  C_  ( R1 `  ( rank `  a ) ) )
59 wess 4511 . . . . . . 7  |-  ( a 
C_  ( R1 `  ( rank `  a )
)  ->  ( b  We  ( R1 `  ( rank `  a ) )  ->  b  We  a
) )
6059eximdv 1629 . . . . . 6  |-  ( a 
C_  ( R1 `  ( rank `  a )
)  ->  ( E. b  b  We  ( R1 `  ( rank `  a
) )  ->  E. b 
b  We  a ) )
6157, 58, 60mp2b 10 . . . . 5  |-  ( E. b  b  We  ( R1 `  ( rank `  a
) )  ->  E. b 
b  We  a )
6251, 56, 613syl 19 . . . 4  |-  ( A. x E. f A. z  e.  x  ( z  =/=  (/)  ->  ( f `  z )  e.  ( ( ~P z  i^i 
Fin )  \  { (/)
} ) )  ->  E. b  b  We  a )
6362alrimiv 1638 . . 3  |-  ( A. x E. f A. z  e.  x  ( z  =/=  (/)  ->  ( f `  z )  e.  ( ( ~P z  i^i 
Fin )  \  { (/)
} ) )  ->  A. a E. b  b  We  a )
64 dfac8 7949 . . 3  |-  (CHOICE  <->  A. a E. b  b  We  a )
6563, 64sylibr 204 . 2  |-  ( A. x E. f A. z  e.  x  ( z  =/=  (/)  ->  ( f `  z )  e.  ( ( ~P z  i^i 
Fin )  \  { (/)
} ) )  -> CHOICE )
6646, 65impbii 181 1  |-  (CHOICE  <->  A. x E. f A. z  e.  x  ( z  =/=  (/)  ->  ( f `  z )  e.  ( ( ~P z  i^i 
Fin )  \  { (/)
} ) ) )
Colors of variables: wff set class
Syntax hints:    -> wi 4    <-> wb 177    /\ w3a 936   A.wal 1546   E.wex 1547    = wceq 1649    e. wcel 1717    =/= wne 2551   A.wral 2650   _Vcvv 2900    \ cdif 3261    i^i cin 3263    C_ wss 3264   (/)c0 3572   ~Pcpw 3743   {csn 3758    e. cmpt 4208    We wwe 4482   Oncon0 4523   ` cfv 5395   Fincfn 7046   R1cr1 7622   rankcrnk 7623  CHOICEwac 7930
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-13 1719  ax-14 1721  ax-6 1736  ax-7 1741  ax-11 1753  ax-12 1939  ax-ext 2369  ax-rep 4262  ax-sep 4272  ax-nul 4280  ax-pow 4319  ax-pr 4345  ax-un 4642  ax-reg 7494  ax-inf2 7530
This theorem depends on definitions:  df-bi 178  df-or 360  df-an 361  df-3or 937  df-3an 938  df-tru 1325  df-ex 1548  df-nf 1551  df-sb 1656  df-eu 2243  df-mo 2244  df-clab 2375  df-cleq 2381  df-clel 2384  df-nfc 2513  df-ne 2553  df-ral 2655  df-rex 2656  df-reu 2657  df-rmo 2658  df-rab 2659  df-v 2902  df-sbc 3106  df-csb 3196  df-dif 3267  df-un 3269  df-in 3271  df-ss 3278  df-pss 3280  df-nul 3573  df-if 3684  df-pw 3745  df-sn 3764  df-pr 3765  df-tp 3766  df-op 3767  df-uni 3959  df-int 3994  df-iun 4038  df-br 4155  df-opab 4209  df-mpt 4210  df-tr 4245  df-eprel 4436  df-id 4440  df-po 4445  df-so 4446  df-fr 4483  df-se 4484  df-we 4485  df-ord 4526  df-on 4527  df-lim 4528  df-suc 4529  df-om 4787  df-xp 4825  df-rel 4826  df-cnv 4827  df-co 4828  df-dm 4829  df-rn 4830  df-res 4831  df-ima 4832  df-iota 5359  df-fun 5397  df-fn 5398  df-f 5399  df-f1 5400  df-fo 5401  df-f1o 5402  df-fv 5403  df-isom 5404  df-ov 6024  df-oprab 6025  df-mpt2 6026  df-1st 6289  df-2nd 6290  df-riota 6486  df-recs 6570  df-rdg 6605  df-1o 6661  df-2o 6662  df-er 6842  df-map 6957  df-en 7047  df-fin 7050  df-sup 7382  df-r1 7624  df-rank 7625  df-card 7760  df-ac 7931
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