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Theorem zorn 7600
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 7599 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 7545 . . 3  |-  ( A  e.  _V  ->  A  e.  dom  card )
31, 2ax-mp 8 . 2  |-  A  e. 
dom  card
4 zorng 7597 . 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 642 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 3    -> wi 4    /\ wa 356   A.wal 1438    e. wcel 1519   A.wral 2271   E.wrex 2272   _Vcvv 2472    C_ wss 2790    C. wpss 2791   U.cuni 3420    Or wor 3860   dom cdm 4252   [ C_] crpss 5747   cardccrd 7040
This theorem is referenced by:  alexsubALTlem2  15557
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-3 7  ax-mp 8  ax-5 1439  ax-6 1440  ax-7 1441  ax-gen 1442  ax-8 1521  ax-11 1522  ax-13 1523  ax-14 1524  ax-17 1526  ax-12o 1559  ax-10 1573  ax-9 1579  ax-4 1586  ax-16 1772  ax-ext 2043  ax-rep 3687  ax-sep 3697  ax-nul 3705  ax-pow 3741  ax-pr 3765  ax-un 4057  ax-ac 7538
This theorem depends on definitions:  df-bi 175  df-or 357  df-an 358  df-3or 894  df-3an 895  df-ex 1444  df-sb 1733  df-eu 1955  df-mo 1956  df-clab 2049  df-cleq 2054  df-clel 2057  df-ne 2181  df-ral 2275  df-rex 2276  df-reu 2277  df-rab 2278  df-v 2474  df-sbc 2648  df-csb 2730  df-dif 2793  df-un 2795  df-in 2797  df-ss 2801  df-pss 2803  df-nul 3070  df-if 3178  df-pw 3239  df-sn 3257  df-pr 3258  df-tp 3259  df-op 3260  df-uni 3421  df-int 3455  df-iun 3498  df-br 3583  df-opab 3637  df-mpt 3638  df-tr 3670  df-eprel 3852  df-id 3856  df-po 3861  df-so 3862  df-fr 3899  df-se 3900  df-we 3901  df-ord 3942  df-on 3943  df-suc 3945  df-xp 4266  df-rel 4267  df-cnv 4268  df-co 4269  df-dm 4270  df-rn 4271  df-res 4272  df-ima 4273  df-fun 4274  df-fn 4275  df-f 4276  df-f1 4277  df-fo 4278  df-f1o 4279  df-fv 4280  df-iso 4281  df-rpss 5748  df-iota 5762  df-recs 5835  df-en 6294  df-riota 6460  df-card 7044  df-ac 7213
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