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Theorem fneqeql2 5839
Description: Two functions are equal iff their equalizer contains the whole domain. (Contributed by Stefan O'Rear, 9-Mar-2015.)
Assertion
Ref Expression
fneqeql2  |-  ( ( F  Fn  A  /\  G  Fn  A )  ->  ( F  =  G  <-> 
A  C_  dom  ( F  i^i  G ) ) )

Proof of Theorem fneqeql2
StepHypRef Expression
1 fneqeql 5838 . 2  |-  ( ( F  Fn  A  /\  G  Fn  A )  ->  ( F  =  G  <->  dom  ( F  i^i  G
)  =  A ) )
2 inss1 3561 . . . . . 6  |-  ( F  i^i  G )  C_  F
3 dmss 5069 . . . . . 6  |-  ( ( F  i^i  G ) 
C_  F  ->  dom  ( F  i^i  G ) 
C_  dom  F )
42, 3ax-mp 8 . . . . 5  |-  dom  ( F  i^i  G )  C_  dom  F
5 fndm 5544 . . . . . 6  |-  ( F  Fn  A  ->  dom  F  =  A )
65adantr 452 . . . . 5  |-  ( ( F  Fn  A  /\  G  Fn  A )  ->  dom  F  =  A )
74, 6syl5sseq 3396 . . . 4  |-  ( ( F  Fn  A  /\  G  Fn  A )  ->  dom  ( F  i^i  G )  C_  A )
87biantrurd 495 . . 3  |-  ( ( F  Fn  A  /\  G  Fn  A )  ->  ( A  C_  dom  ( F  i^i  G )  <-> 
( dom  ( F  i^i  G )  C_  A  /\  A  C_  dom  ( F  i^i  G ) ) ) )
9 eqss 3363 . . 3  |-  ( dom  ( F  i^i  G
)  =  A  <->  ( dom  ( F  i^i  G ) 
C_  A  /\  A  C_ 
dom  ( F  i^i  G ) ) )
108, 9syl6rbbr 256 . 2  |-  ( ( F  Fn  A  /\  G  Fn  A )  ->  ( dom  ( F  i^i  G )  =  A  <->  A  C_  dom  ( F  i^i  G ) ) )
111, 10bitrd 245 1  |-  ( ( F  Fn  A  /\  G  Fn  A )  ->  ( F  =  G  <-> 
A  C_  dom  ( F  i^i  G ) ) )
Colors of variables: wff set class
Syntax hints:    -> wi 4    <-> wb 177    /\ wa 359    = wceq 1652    i^i cin 3319    C_ wss 3320   dom cdm 4878    Fn wfn 5449
This theorem is referenced by:  evlseu  19937  hauseqcn  24293
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-3 7  ax-mp 8  ax-gen 1555  ax-5 1566  ax-17 1626  ax-9 1666  ax-8 1687  ax-13 1727  ax-14 1729  ax-6 1744  ax-7 1749  ax-11 1761  ax-12 1950  ax-ext 2417  ax-sep 4330  ax-nul 4338  ax-pow 4377  ax-pr 4403
This theorem depends on definitions:  df-bi 178  df-or 360  df-an 361  df-3an 938  df-tru 1328  df-ex 1551  df-nf 1554  df-sb 1659  df-eu 2285  df-mo 2286  df-clab 2423  df-cleq 2429  df-clel 2432  df-nfc 2561  df-ne 2601  df-ral 2710  df-rex 2711  df-rab 2714  df-v 2958  df-sbc 3162  df-csb 3252  df-dif 3323  df-un 3325  df-in 3327  df-ss 3334  df-nul 3629  df-if 3740  df-sn 3820  df-pr 3821  df-op 3823  df-uni 4016  df-br 4213  df-opab 4267  df-mpt 4268  df-id 4498  df-xp 4884  df-rel 4885  df-cnv 4886  df-co 4887  df-dm 4888  df-rn 4889  df-res 4890  df-ima 4891  df-iota 5418  df-fun 5456  df-fn 5457  df-fv 5462
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