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Theorem zorn 8015
Description: Zorn's Lemma. If the union of every chain (with respect to inclusion) in a set belongs to the set, then the set contains a maximal element. This theorem is equivalent to the Axiom of Choice. Theorem 6M of [Enderton] p. 151. See zorn2 8014 for a version with general partial orderings. (Contributed by NM, 12-Aug-2004.)
Hypothesis
Ref Expression
zornn0.1  |-  A  e. 
_V
Assertion
Ref Expression
zorn  |-  ( A. z ( ( z 
C_  A  /\ [ C.]  Or  z )  ->  U. z  e.  A )  ->  E. x  e.  A  A. y  e.  A  -.  x  C.  y )
Distinct variable group:    x, y, z, A

Proof of Theorem zorn
StepHypRef Expression
1 zornn0.1 . . 3  |-  A  e. 
_V
2 numth3 7978 . . 3  |-  ( A  e.  _V  ->  A  e.  dom  card )
31, 2ax-mp 10 . 2  |-  A  e. 
dom  card
4 zorng 8012 . 2  |-  ( ( A  e.  dom  card  /\ 
A. z ( ( z  C_  A  /\ [ C.] 
Or  z )  ->  U. z  e.  A
) )  ->  E. x  e.  A  A. y  e.  A  -.  x  C.  y )
53, 4mpan 654 1  |-  ( A. z ( ( z 
C_  A  /\ [ C.]  Or  z )  ->  U. z  e.  A )  ->  E. x  e.  A  A. y  e.  A  -.  x  C.  y )
Colors of variables: wff set class
Syntax hints:   -. wn 5    -> wi 6    /\ wa 360   A.wal 1532    e. wcel 1621   A.wral 2507   E.wrex 2508   _Vcvv 2725    C_ wss 3075    C. wpss 3076   U.cuni 3724    Or wor 4203   dom cdm 4577   [ C.] crpss 6125   cardccrd 7449
This theorem is referenced by:  alexsubALTlem2  17536
This theorem was proved from axioms:  ax-1 7  ax-2 8  ax-3 9  ax-mp 10  ax-5 1533  ax-6 1534  ax-7 1535  ax-gen 1536  ax-8 1623  ax-11 1624  ax-13 1625  ax-14 1626  ax-17 1628  ax-12o 1664  ax-10 1678  ax-9 1684  ax-4 1692  ax-16 1926  ax-ext 2234  ax-rep 4025  ax-sep 4035  ax-nul 4043  ax-pow 4079  ax-pr 4105  ax-un 4400  ax-ac2 7970
This theorem depends on definitions:  df-bi 179  df-or 361  df-an 362  df-3or 940  df-3an 941  df-tru 1315  df-ex 1538  df-nf 1540  df-sb 1883  df-eu 2118  df-mo 2119  df-clab 2240  df-cleq 2246  df-clel 2249  df-nfc 2374  df-ne 2414  df-ral 2511  df-rex 2512  df-reu 2513  df-rab 2514  df-v 2727  df-sbc 2920  df-csb 3007  df-dif 3078  df-un 3080  df-in 3082  df-ss 3086  df-pss 3088  df-nul 3360  df-if 3468  df-pw 3529  df-sn 3547  df-pr 3548  df-tp 3549  df-op 3550  df-uni 3725  df-int 3758  df-iun 3802  df-br 3918  df-opab 3972  df-mpt 3973  df-tr 4008  df-eprel 4195  df-id 4199  df-po 4204  df-so 4205  df-fr 4242  df-se 4243  df-we 4244  df-ord 4285  df-on 4286  df-suc 4288  df-xp 4591  df-rel 4592  df-cnv 4593  df-co 4594  df-dm 4595  df-rn 4596  df-res 4597  df-ima 4598  df-fun 4599  df-fn 4600  df-f 4601  df-f1 4602  df-fo 4603  df-f1o 4604  df-fv 4605  df-isom 4606  df-rpss 6126  df-iota 6140  df-riota 6187  df-recs 6271  df-en 6747  df-card 7453  df-ac 7624
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