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Theorem zorn 7610
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 7609 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 7555 . . 3  |-  ( A  e.  _V  ->  A  e.  dom  card )
31, 2ax-mp 8 . 2  |-  A  e. 
dom  card
4 zorng 7607 . 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 644 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 1441    e. wcel 1522   A.wral 2274   E.wrex 2275   _Vcvv 2475    C_ wss 2793    C. wpss 2794   U.cuni 3424    Or wor 3864   dom cdm 4256   [ C_] crpss 5755   cardccrd 7050
This theorem is referenced by:  alexsubALTlem2  16429
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-3 7  ax-mp 8  ax-5 1442  ax-6 1443  ax-7 1444  ax-gen 1445  ax-8 1524  ax-11 1525  ax-13 1526  ax-14 1527  ax-17 1529  ax-12o 1562  ax-10 1576  ax-9 1582  ax-4 1589  ax-16 1775  ax-ext 2046  ax-rep 3691  ax-sep 3701  ax-nul 3709  ax-pow 3745  ax-pr 3769  ax-un 4061  ax-ac 7548
This theorem depends on definitions:  df-bi 175  df-or 357  df-an 358  df-3or 897  df-3an 898  df-ex 1447  df-sb 1736  df-eu 1958  df-mo 1959  df-clab 2052  df-cleq 2057  df-clel 2060  df-ne 2184  df-ral 2278  df-rex 2279  df-reu 2280  df-rab 2281  df-v 2477  df-sbc 2651  df-csb 2733  df-dif 2796  df-un 2798  df-in 2800  df-ss 2804  df-pss 2806  df-nul 3073  df-if 3182  df-pw 3243  df-sn 3261  df-pr 3262  df-tp 3263  df-op 3264  df-uni 3425  df-int 3459  df-iun 3502  df-br 3587  df-opab 3641  df-mpt 3642  df-tr 3674  df-eprel 3856  df-id 3860  df-po 3865  df-so 3866  df-fr 3903  df-se 3904  df-we 3905  df-ord 3946  df-on 3947  df-suc 3949  df-xp 4270  df-rel 4271  df-cnv 4272  df-co 4273  df-dm 4274  df-rn 4275  df-res 4276  df-ima 4277  df-fun 4278  df-fn 4279  df-f 4280  df-f1 4281  df-fo 4282  df-f1o 4283  df-fv 4284  df-iso 4285  df-rpss 5756  df-iota 5770  df-recs 5843  df-en 6302  df-riota 6468  df-card 7054  df-ac 7223
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