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Theorem fodomb 8797
Description: Equivalence of an onto mapping and dominance for a nonempty set. Proposition 10.35 of [TakeutiZaring] p. 93. (Contributed by NM, 29-Jul-2004.)
Assertion
Ref Expression
fodomb  |-  ( ( A  =/=  (/)  /\  E. f  f : A -onto-> B )  <->  ( (/)  ~<  B  /\  B  ~<_  A ) )
Distinct variable groups:    A, f    B, f

Proof of Theorem fodomb
StepHypRef Expression
1 fof 5721 . . . . . . . . . . . 12  |-  ( f : A -onto-> B  -> 
f : A --> B )
2 fdm 5664 . . . . . . . . . . . 12  |-  ( f : A --> B  ->  dom  f  =  A
)
31, 2syl 16 . . . . . . . . . . 11  |-  ( f : A -onto-> B  ->  dom  f  =  A
)
43eqeq1d 2453 . . . . . . . . . 10  |-  ( f : A -onto-> B  -> 
( dom  f  =  (/)  <->  A  =  (/) ) )
5 dm0rn0 5157 . . . . . . . . . . 11  |-  ( dom  f  =  (/)  <->  ran  f  =  (/) )
6 forn 5724 . . . . . . . . . . . 12  |-  ( f : A -onto-> B  ->  ran  f  =  B
)
76eqeq1d 2453 . . . . . . . . . . 11  |-  ( f : A -onto-> B  -> 
( ran  f  =  (/)  <->  B  =  (/) ) )
85, 7syl5bb 257 . . . . . . . . . 10  |-  ( f : A -onto-> B  -> 
( dom  f  =  (/)  <->  B  =  (/) ) )
94, 8bitr3d 255 . . . . . . . . 9  |-  ( f : A -onto-> B  -> 
( A  =  (/)  <->  B  =  (/) ) )
109necon3bid 2706 . . . . . . . 8  |-  ( f : A -onto-> B  -> 
( A  =/=  (/)  <->  B  =/=  (/) ) )
1110biimpac 486 . . . . . . 7  |-  ( ( A  =/=  (/)  /\  f : A -onto-> B )  ->  B  =/=  (/) )
12 vex 3074 . . . . . . . . . . . 12  |-  f  e. 
_V
1312dmex 6614 . . . . . . . . . . 11  |-  dom  f  e.  _V
143, 13syl6eqelr 2548 . . . . . . . . . 10  |-  ( f : A -onto-> B  ->  A  e.  _V )
15 fornex 6649 . . . . . . . . . 10  |-  ( A  e.  _V  ->  (
f : A -onto-> B  ->  B  e.  _V )
)
1614, 15mpcom 36 . . . . . . . . 9  |-  ( f : A -onto-> B  ->  B  e.  _V )
17 0sdomg 7543 . . . . . . . . 9  |-  ( B  e.  _V  ->  ( (/) 
~<  B  <->  B  =/=  (/) ) )
1816, 17syl 16 . . . . . . . 8  |-  ( f : A -onto-> B  -> 
( (/)  ~<  B  <->  B  =/=  (/) ) )
1918adantl 466 . . . . . . 7  |-  ( ( A  =/=  (/)  /\  f : A -onto-> B )  ->  ( (/) 
~<  B  <->  B  =/=  (/) ) )
2011, 19mpbird 232 . . . . . 6  |-  ( ( A  =/=  (/)  /\  f : A -onto-> B )  ->  (/)  ~<  B )
2120ex 434 . . . . 5  |-  ( A  =/=  (/)  ->  ( f : A -onto-> B  ->  (/)  ~<  B ) )
22 fodomg 8796 . . . . . . 7  |-  ( A  e.  _V  ->  (
f : A -onto-> B  ->  B  ~<_  A ) )
2314, 22mpcom 36 . . . . . 6  |-  ( f : A -onto-> B  ->  B  ~<_  A )
2423a1i 11 . . . . 5  |-  ( A  =/=  (/)  ->  ( f : A -onto-> B  ->  B  ~<_  A ) )
2521, 24jcad 533 . . . 4  |-  ( A  =/=  (/)  ->  ( f : A -onto-> B  ->  ( (/)  ~<  B  /\  B  ~<_  A ) ) )
2625exlimdv 1691 . . 3  |-  ( A  =/=  (/)  ->  ( E. f  f : A -onto-> B  ->  ( (/)  ~<  B  /\  B  ~<_  A ) ) )
2726imp 429 . 2  |-  ( ( A  =/=  (/)  /\  E. f  f : A -onto-> B )  ->  ( (/) 
~<  B  /\  B  ~<_  A ) )
28 sdomdomtr 7547 . . . 4  |-  ( (
(/)  ~<  B  /\  B  ~<_  A )  ->  (/)  ~<  A )
29 reldom 7419 . . . . . . 7  |-  Rel  ~<_
3029brrelex2i 4981 . . . . . 6  |-  ( B  ~<_  A  ->  A  e.  _V )
3130adantl 466 . . . . 5  |-  ( (
(/)  ~<  B  /\  B  ~<_  A )  ->  A  e.  _V )
32 0sdomg 7543 . . . . 5  |-  ( A  e.  _V  ->  ( (/) 
~<  A  <->  A  =/=  (/) ) )
3331, 32syl 16 . . . 4  |-  ( (
(/)  ~<  B  /\  B  ~<_  A )  ->  ( (/) 
~<  A  <->  A  =/=  (/) ) )
3428, 33mpbid 210 . . 3  |-  ( (
(/)  ~<  B  /\  B  ~<_  A )  ->  A  =/=  (/) )
35 fodomr 7565 . . 3  |-  ( (
(/)  ~<  B  /\  B  ~<_  A )  ->  E. f 
f : A -onto-> B
)
3634, 35jca 532 . 2  |-  ( (
(/)  ~<  B  /\  B  ~<_  A )  ->  ( A  =/=  (/)  /\  E. f 
f : A -onto-> B
) )
3727, 36impbii 188 1  |-  ( ( A  =/=  (/)  /\  E. f  f : A -onto-> B )  <->  ( (/)  ~<  B  /\  B  ~<_  A ) )
Colors of variables: wff setvar class
Syntax hints:    -> wi 4    <-> wb 184    /\ wa 369    = wceq 1370   E.wex 1587    e. wcel 1758    =/= wne 2644   _Vcvv 3071   (/)c0 3738   class class class wbr 4393   dom cdm 4941   ran crn 4942   -->wf 5515   -onto->wfo 5517    ~<_ cdom 7411    ~< csdm 7412
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1592  ax-4 1603  ax-5 1671  ax-6 1710  ax-7 1730  ax-8 1760  ax-9 1762  ax-10 1777  ax-11 1782  ax-12 1794  ax-13 1952  ax-ext 2430  ax-rep 4504  ax-sep 4514  ax-nul 4522  ax-pow 4571  ax-pr 4632  ax-un 6475  ax-ac2 8736
This theorem depends on definitions:  df-bi 185  df-or 370  df-an 371  df-3or 966  df-3an 967  df-tru 1373  df-ex 1588  df-nf 1591  df-sb 1703  df-eu 2264  df-mo 2265  df-clab 2437  df-cleq 2443  df-clel 2446  df-nfc 2601  df-ne 2646  df-ral 2800  df-rex 2801  df-reu 2802  df-rmo 2803  df-rab 2804  df-v 3073  df-sbc 3288  df-csb 3390  df-dif 3432  df-un 3434  df-in 3436  df-ss 3443  df-pss 3445  df-nul 3739  df-if 3893  df-pw 3963  df-sn 3979  df-pr 3981  df-tp 3983  df-op 3985  df-uni 4193  df-int 4230  df-iun 4274  df-br 4394  df-opab 4452  df-mpt 4453  df-tr 4487  df-eprel 4733  df-id 4737  df-po 4742  df-so 4743  df-fr 4780  df-se 4781  df-we 4782  df-ord 4823  df-on 4824  df-suc 4826  df-xp 4947  df-rel 4948  df-cnv 4949  df-co 4950  df-dm 4951  df-rn 4952  df-res 4953  df-ima 4954  df-iota 5482  df-fun 5521  df-fn 5522  df-f 5523  df-f1 5524  df-fo 5525  df-f1o 5526  df-fv 5527  df-isom 5528  df-riota 6154  df-ov 6196  df-oprab 6197  df-mpt2 6198  df-1st 6680  df-2nd 6681  df-recs 6935  df-er 7204  df-map 7319  df-en 7414  df-dom 7415  df-sdom 7416  df-card 8213  df-acn 8216  df-ac 8390
This theorem is referenced by: (None)
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