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Theorem 1stcof 6333
Description: Composition of the first member function with another function. (Contributed by NM, 12-Oct-2007.)
Assertion
Ref Expression
1stcof  |-  ( F : A --> ( B  X.  C )  -> 
( 1st  o.  F
) : A --> B )

Proof of Theorem 1stcof
StepHypRef Expression
1 fo1st 6325 . . . 4  |-  1st : _V -onto-> _V
2 fofn 5614 . . . 4  |-  ( 1st
: _V -onto-> _V  ->  1st 
Fn  _V )
31, 2ax-mp 8 . . 3  |-  1st  Fn  _V
4 ffn 5550 . . . 4  |-  ( F : A --> ( B  X.  C )  ->  F  Fn  A )
5 dffn2 5551 . . . 4  |-  ( F  Fn  A  <->  F : A
--> _V )
64, 5sylib 189 . . 3  |-  ( F : A --> ( B  X.  C )  ->  F : A --> _V )
7 fnfco 5568 . . 3  |-  ( ( 1st  Fn  _V  /\  F : A --> _V )  ->  ( 1st  o.  F
)  Fn  A )
83, 6, 7sylancr 645 . 2  |-  ( F : A --> ( B  X.  C )  -> 
( 1st  o.  F
)  Fn  A )
9 rnco 5335 . . 3  |-  ran  ( 1st  o.  F )  =  ran  ( 1st  |`  ran  F
)
10 frn 5556 . . . . 5  |-  ( F : A --> ( B  X.  C )  ->  ran  F  C_  ( B  X.  C ) )
11 ssres2 5132 . . . . 5  |-  ( ran 
F  C_  ( B  X.  C )  ->  ( 1st  |`  ran  F ) 
C_  ( 1st  |`  ( B  X.  C ) ) )
12 rnss 5057 . . . . 5  |-  ( ( 1st  |`  ran  F ) 
C_  ( 1st  |`  ( B  X.  C ) )  ->  ran  ( 1st  |` 
ran  F )  C_  ran  ( 1st  |`  ( B  X.  C ) ) )
1310, 11, 123syl 19 . . . 4  |-  ( F : A --> ( B  X.  C )  ->  ran  ( 1st  |`  ran  F
)  C_  ran  ( 1st  |`  ( B  X.  C
) ) )
14 f1stres 6327 . . . . 5  |-  ( 1st  |`  ( B  X.  C
) ) : ( B  X.  C ) --> B
15 frn 5556 . . . . 5  |-  ( ( 1st  |`  ( B  X.  C ) ) : ( B  X.  C
) --> B  ->  ran  ( 1st  |`  ( B  X.  C ) )  C_  B )
1614, 15ax-mp 8 . . . 4  |-  ran  ( 1st  |`  ( B  X.  C ) )  C_  B
1713, 16syl6ss 3320 . . 3  |-  ( F : A --> ( B  X.  C )  ->  ran  ( 1st  |`  ran  F
)  C_  B )
189, 17syl5eqss 3352 . 2  |-  ( F : A --> ( B  X.  C )  ->  ran  ( 1st  o.  F
)  C_  B )
19 df-f 5417 . 2  |-  ( ( 1st  o.  F ) : A --> B  <->  ( ( 1st  o.  F )  Fn  A  /\  ran  ( 1st  o.  F )  C_  B ) )
208, 18, 19sylanbrc 646 1  |-  ( F : A --> ( B  X.  C )  -> 
( 1st  o.  F
) : A --> B )
Colors of variables: wff set class
Syntax hints:    -> wi 4   _Vcvv 2916    C_ wss 3280    X. cxp 4835   ran crn 4838    |` cres 4839    o. ccom 4841    Fn wfn 5408   -->wf 5409   -onto->wfo 5411   1stc1st 6306
This theorem is referenced by:  ruclem11  12794  ruclem12  12795  caubl  19213
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 1662  ax-8 1683  ax-13 1723  ax-14 1725  ax-6 1740  ax-7 1745  ax-11 1757  ax-12 1946  ax-ext 2385  ax-sep 4290  ax-nul 4298  ax-pr 4363  ax-un 4660
This theorem depends on definitions:  df-bi 178  df-or 360  df-an 361  df-3an 938  df-tru 1325  df-ex 1548  df-nf 1551  df-sb 1656  df-eu 2258  df-mo 2259  df-clab 2391  df-cleq 2397  df-clel 2400  df-nfc 2529  df-ne 2569  df-ral 2671  df-rex 2672  df-rab 2675  df-v 2918  df-sbc 3122  df-csb 3212  df-dif 3283  df-un 3285  df-in 3287  df-ss 3294  df-nul 3589  df-if 3700  df-sn 3780  df-pr 3781  df-op 3783  df-uni 3976  df-iun 4055  df-br 4173  df-opab 4227  df-mpt 4228  df-id 4458  df-xp 4843  df-rel 4844  df-cnv 4845  df-co 4846  df-dm 4847  df-rn 4848  df-res 4849  df-ima 4850  df-iota 5377  df-fun 5415  df-fn 5416  df-f 5417  df-fo 5419  df-fv 5421  df-1st 6308
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