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Theorem php 7691
Description: Pigeonhole Principle. A natural number is not equinumerous to a proper subset of itself. Theorem (Pigeonhole Principle) of [Enderton] p. 134. The theorem is so-called because you can't put n + 1 pigeons into n holes (if each hole holds only one pigeon). The proof consists of lemmas phplem1 7686 through phplem4 7689, nneneq 7690, and this final piece of the proof. (Contributed by NM, 29-May-1998.)
Assertion
Ref Expression
php  |-  ( ( A  e.  om  /\  B  C.  A )  ->  -.  A  ~~  B )

Proof of Theorem php
Dummy variables  x  y are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 0ss 3807 . . . . . . . 8  |-  (/)  C_  B
2 sspsstr 3602 . . . . . . . 8  |-  ( (
(/)  C_  B  /\  B  C.  A )  ->  (/)  C.  A
)
31, 2mpan 670 . . . . . . 7  |-  ( B 
C.  A  ->  (/)  C.  A
)
4 0pss 3857 . . . . . . . 8  |-  ( (/)  C.  A  <->  A  =/=  (/) )
5 df-ne 2657 . . . . . . . 8  |-  ( A  =/=  (/)  <->  -.  A  =  (/) )
64, 5bitri 249 . . . . . . 7  |-  ( (/)  C.  A  <->  -.  A  =  (/) )
73, 6sylib 196 . . . . . 6  |-  ( B 
C.  A  ->  -.  A  =  (/) )
8 nn0suc 6695 . . . . . . 7  |-  ( A  e.  om  ->  ( A  =  (/)  \/  E. x  e.  om  A  =  suc  x ) )
98orcanai 906 . . . . . 6  |-  ( ( A  e.  om  /\  -.  A  =  (/) )  ->  E. x  e.  om  A  =  suc  x )
107, 9sylan2 474 . . . . 5  |-  ( ( A  e.  om  /\  B  C.  A )  ->  E. x  e.  om  A  =  suc  x )
11 pssnel 3885 . . . . . . . . . 10  |-  ( B 
C.  suc  x  ->  E. y ( y  e. 
suc  x  /\  -.  y  e.  B )
)
12 pssss 3592 . . . . . . . . . . . . . . . . 17  |-  ( B 
C.  suc  x  ->  B 
C_  suc  x )
13 ssdif 3632 . . . . . . . . . . . . . . . . . 18  |-  ( B 
C_  suc  x  ->  ( B  \  { y } )  C_  ( suc  x  \  { y } ) )
14 disjsn 4081 . . . . . . . . . . . . . . . . . . . 20  |-  ( ( B  i^i  { y } )  =  (/)  <->  -.  y  e.  B )
15 disj3 3864 . . . . . . . . . . . . . . . . . . . 20  |-  ( ( B  i^i  { y } )  =  (/)  <->  B  =  ( B  \  { y } ) )
1614, 15bitr3i 251 . . . . . . . . . . . . . . . . . . 19  |-  ( -.  y  e.  B  <->  B  =  ( B  \  { y } ) )
17 sseq1 3518 . . . . . . . . . . . . . . . . . . 19  |-  ( B  =  ( B  \  { y } )  ->  ( B  C_  ( suc  x  \  {
y } )  <->  ( B  \  { y } ) 
C_  ( suc  x  \  { y } ) ) )
1816, 17sylbi 195 . . . . . . . . . . . . . . . . . 18  |-  ( -.  y  e.  B  -> 
( B  C_  ( suc  x  \  { y } )  <->  ( B  \  { y } ) 
C_  ( suc  x  \  { y } ) ) )
1913, 18syl5ibr 221 . . . . . . . . . . . . . . . . 17  |-  ( -.  y  e.  B  -> 
( B  C_  suc  x  ->  B  C_  ( suc  x  \  { y } ) ) )
20 vex 3109 . . . . . . . . . . . . . . . . . . . 20  |-  x  e. 
_V
2120sucex 6617 . . . . . . . . . . . . . . . . . . 19  |-  suc  x  e.  _V
22 difss 3624 . . . . . . . . . . . . . . . . . . 19  |-  ( suc  x  \  { y } )  C_  suc  x
2321, 22ssexi 4585 . . . . . . . . . . . . . . . . . 18  |-  ( suc  x  \  { y } )  e.  _V
24 ssdomg 7551 . . . . . . . . . . . . . . . . . 18  |-  ( ( suc  x  \  {
y } )  e. 
_V  ->  ( B  C_  ( suc  x  \  {
y } )  ->  B  ~<_  ( suc  x  \  { y } ) ) )
2523, 24ax-mp 5 . . . . . . . . . . . . . . . . 17  |-  ( B 
C_  ( suc  x  \  { y } )  ->  B  ~<_  ( suc  x  \  { y } ) )
2612, 19, 25syl56 34 . . . . . . . . . . . . . . . 16  |-  ( -.  y  e.  B  -> 
( B  C.  suc  x  ->  B  ~<_  ( suc  x  \  { y } ) ) )
2726imp 429 . . . . . . . . . . . . . . 15  |-  ( ( -.  y  e.  B  /\  B  C.  suc  x
)  ->  B  ~<_  ( suc  x  \  { y } ) )
28 vex 3109 . . . . . . . . . . . . . . . . 17  |-  y  e. 
_V
2920, 28phplem3 7688 . . . . . . . . . . . . . . . 16  |-  ( ( x  e.  om  /\  y  e.  suc  x )  ->  x  ~~  ( suc  x  \  { y } ) )
3029ensymd 7556 . . . . . . . . . . . . . . 15  |-  ( ( x  e.  om  /\  y  e.  suc  x )  ->  ( suc  x  \  { y } ) 
~~  x )
31 domentr 7564 . . . . . . . . . . . . . . 15  |-  ( ( B  ~<_  ( suc  x  \  { y } )  /\  ( suc  x  \  { y } ) 
~~  x )  ->  B  ~<_  x )
3227, 30, 31syl2an 477 . . . . . . . . . . . . . 14  |-  ( ( ( -.  y  e.  B  /\  B  C.  suc  x )  /\  (
x  e.  om  /\  y  e.  suc  x ) )  ->  B  ~<_  x )
3332exp43 612 . . . . . . . . . . . . 13  |-  ( -.  y  e.  B  -> 
( B  C.  suc  x  ->  ( x  e.  om  ->  ( y  e.  suc  x  ->  B  ~<_  x ) ) ) )
3433com4r 86 . . . . . . . . . . . 12  |-  ( y  e.  suc  x  -> 
( -.  y  e.  B  ->  ( B  C. 
suc  x  ->  (
x  e.  om  ->  B  ~<_  x ) ) ) )
3534imp 429 . . . . . . . . . . 11  |-  ( ( y  e.  suc  x  /\  -.  y  e.  B
)  ->  ( B  C. 
suc  x  ->  (
x  e.  om  ->  B  ~<_  x ) ) )
3635exlimiv 1693 . . . . . . . . . 10  |-  ( E. y ( y  e. 
suc  x  /\  -.  y  e.  B )  ->  ( B  C.  suc  x  ->  ( x  e.  om  ->  B  ~<_  x ) ) )
3711, 36mpcom 36 . . . . . . . . 9  |-  ( B 
C.  suc  x  ->  ( x  e.  om  ->  B  ~<_  x ) )
38 endomtr 7563 . . . . . . . . . . . 12  |-  ( ( suc  x  ~~  B  /\  B  ~<_  x )  ->  suc  x  ~<_  x )
39 sssucid 4948 . . . . . . . . . . . . 13  |-  x  C_  suc  x
40 ssdomg 7551 . . . . . . . . . . . . 13  |-  ( suc  x  e.  _V  ->  ( x  C_  suc  x  ->  x  ~<_  suc  x )
)
4121, 39, 40mp2 9 . . . . . . . . . . . 12  |-  x  ~<_  suc  x
42 sbth 7627 . . . . . . . . . . . 12  |-  ( ( suc  x  ~<_  x  /\  x  ~<_  suc  x )  ->  suc  x  ~~  x
)
4338, 41, 42sylancl 662 . . . . . . . . . . 11  |-  ( ( suc  x  ~~  B  /\  B  ~<_  x )  ->  suc  x  ~~  x
)
4443expcom 435 . . . . . . . . . 10  |-  ( B  ~<_  x  ->  ( suc  x  ~~  B  ->  suc  x  ~~  x ) )
45 peano2b 6687 . . . . . . . . . . . . 13  |-  ( x  e.  om  <->  suc  x  e. 
om )
46 nnord 6679 . . . . . . . . . . . . 13  |-  ( suc  x  e.  om  ->  Ord 
suc  x )
4745, 46sylbi 195 . . . . . . . . . . . 12  |-  ( x  e.  om  ->  Ord  suc  x )
4820sucid 4950 . . . . . . . . . . . 12  |-  x  e. 
suc  x
49 nordeq 4890 . . . . . . . . . . . 12  |-  ( ( Ord  suc  x  /\  x  e.  suc  x )  ->  suc  x  =/=  x )
5047, 48, 49sylancl 662 . . . . . . . . . . 11  |-  ( x  e.  om  ->  suc  x  =/=  x )
51 nneneq 7690 . . . . . . . . . . . . . 14  |-  ( ( suc  x  e.  om  /\  x  e.  om )  ->  ( suc  x  ~~  x 
<->  suc  x  =  x ) )
5245, 51sylanb 472 . . . . . . . . . . . . 13  |-  ( ( x  e.  om  /\  x  e.  om )  ->  ( suc  x  ~~  x 
<->  suc  x  =  x ) )
5352anidms 645 . . . . . . . . . . . 12  |-  ( x  e.  om  ->  ( suc  x  ~~  x  <->  suc  x  =  x ) )
5453necon3bbid 2707 . . . . . . . . . . 11  |-  ( x  e.  om  ->  ( -.  suc  x  ~~  x  <->  suc  x  =/=  x ) )
5550, 54mpbird 232 . . . . . . . . . 10  |-  ( x  e.  om  ->  -.  suc  x  ~~  x )
5644, 55nsyli 141 . . . . . . . . 9  |-  ( B  ~<_  x  ->  ( x  e.  om  ->  -.  suc  x  ~~  B ) )
5737, 56syli 37 . . . . . . . 8  |-  ( B 
C.  suc  x  ->  ( x  e.  om  ->  -. 
suc  x  ~~  B
) )
5857com12 31 . . . . . . 7  |-  ( x  e.  om  ->  ( B  C.  suc  x  ->  -.  suc  x  ~~  B
) )
59 psseq2 3585 . . . . . . . 8  |-  ( A  =  suc  x  -> 
( B  C.  A  <->  B 
C.  suc  x )
)
60 breq1 4443 . . . . . . . . 9  |-  ( A  =  suc  x  -> 
( A  ~~  B  <->  suc  x  ~~  B ) )
6160notbid 294 . . . . . . . 8  |-  ( A  =  suc  x  -> 
( -.  A  ~~  B 
<->  -.  suc  x  ~~  B ) )
6259, 61imbi12d 320 . . . . . . 7  |-  ( A  =  suc  x  -> 
( ( B  C.  A  ->  -.  A  ~~  B )  <->  ( B  C. 
suc  x  ->  -.  suc  x  ~~  B ) ) )
6358, 62syl5ibrcom 222 . . . . . 6  |-  ( x  e.  om  ->  ( A  =  suc  x  -> 
( B  C.  A  ->  -.  A  ~~  B
) ) )
6463rexlimiv 2942 . . . . 5  |-  ( E. x  e.  om  A  =  suc  x  ->  ( B  C.  A  ->  -.  A  ~~  B ) )
6510, 64syl 16 . . . 4  |-  ( ( A  e.  om  /\  B  C.  A )  -> 
( B  C.  A  ->  -.  A  ~~  B
) )
6665ex 434 . . 3  |-  ( A  e.  om  ->  ( B  C.  A  ->  ( B  C.  A  ->  -.  A  ~~  B ) ) )
6766pm2.43d 48 . 2  |-  ( A  e.  om  ->  ( B  C.  A  ->  -.  A  ~~  B ) )
6867imp 429 1  |-  ( ( A  e.  om  /\  B  C.  A )  ->  -.  A  ~~  B )
Colors of variables: wff setvar class
Syntax hints:   -. wn 3    -> wi 4    <-> wb 184    /\ wa 369    = wceq 1374   E.wex 1591    e. wcel 1762    =/= wne 2655   E.wrex 2808   _Vcvv 3106    \ cdif 3466    i^i cin 3468    C_ wss 3469    C. wpss 3470   (/)c0 3778   {csn 4020   class class class wbr 4440   Ord word 4870   suc csuc 4873   omcom 6671    ~~ cen 7503    ~<_ cdom 7504
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1596  ax-4 1607  ax-5 1675  ax-6 1714  ax-7 1734  ax-8 1764  ax-9 1766  ax-10 1781  ax-11 1786  ax-12 1798  ax-13 1961  ax-ext 2438  ax-sep 4561  ax-nul 4569  ax-pow 4618  ax-pr 4679  ax-un 6567
This theorem depends on definitions:  df-bi 185  df-or 370  df-an 371  df-3or 969  df-3an 970  df-tru 1377  df-ex 1592  df-nf 1595  df-sb 1707  df-eu 2272  df-mo 2273  df-clab 2446  df-cleq 2452  df-clel 2455  df-nfc 2610  df-ne 2657  df-ral 2812  df-rex 2813  df-rab 2816  df-v 3108  df-sbc 3325  df-dif 3472  df-un 3474  df-in 3476  df-ss 3483  df-pss 3485  df-nul 3779  df-if 3933  df-pw 4005  df-sn 4021  df-pr 4023  df-tp 4025  df-op 4027  df-uni 4239  df-br 4441  df-opab 4499  df-tr 4534  df-eprel 4784  df-id 4788  df-po 4793  df-so 4794  df-fr 4831  df-we 4833  df-ord 4874  df-on 4875  df-lim 4876  df-suc 4877  df-xp 4998  df-rel 4999  df-cnv 5000  df-co 5001  df-dm 5002  df-rn 5003  df-res 5004  df-ima 5005  df-iota 5542  df-fun 5581  df-fn 5582  df-f 5583  df-f1 5584  df-fo 5585  df-f1o 5586  df-fv 5587  df-om 6672  df-er 7301  df-en 7507  df-dom 7508
This theorem is referenced by:  php2  7692  php3  7693
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