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Theorem infdif 7803
Description: The cardinality of an infinite set does not change after subtracting a strictly smaller one. Example in [Enderton] p. 164. (Contributed by NM, 22-Oct-2004.) (Revised by Mario Carneiro, 29-Apr-2015.)
Assertion
Ref Expression
infdif  |-  ( ( A  e.  dom  card  /\ 
om  ~<_  A  /\  B  ~<  A )  ->  ( A  \  B )  ~~  A )

Proof of Theorem infdif
StepHypRef Expression
1 simp1 960 . . 3  |-  ( ( A  e.  dom  card  /\ 
om  ~<_  A  /\  B  ~<  A )  ->  A  e.  dom  card )
2 difss 3278 . . 3  |-  ( A 
\  B )  C_  A
3 ssdomg 6875 . . 3  |-  ( A  e.  dom  card  ->  ( ( A  \  B
)  C_  A  ->  ( A  \  B )  ~<_  A ) )
41, 2, 3ee10 1372 . 2  |-  ( ( A  e.  dom  card  /\ 
om  ~<_  A  /\  B  ~<  A )  ->  ( A  \  B )  ~<_  A )
5 sdomdom 6857 . . . . . . . . 9  |-  ( B 
~<  A  ->  B  ~<_  A )
653ad2ant3 983 . . . . . . . 8  |-  ( ( A  e.  dom  card  /\ 
om  ~<_  A  /\  B  ~<  A )  ->  B  ~<_  A )
7 numdom 7633 . . . . . . . 8  |-  ( ( A  e.  dom  card  /\  B  ~<_  A )  ->  B  e.  dom  card )
81, 6, 7syl2anc 645 . . . . . . 7  |-  ( ( A  e.  dom  card  /\ 
om  ~<_  A  /\  B  ~<  A )  ->  B  e.  dom  card )
9 unnum 7794 . . . . . . 7  |-  ( ( A  e.  dom  card  /\  B  e.  dom  card )  ->  ( A  u.  B )  e.  dom  card )
101, 8, 9syl2anc 645 . . . . . 6  |-  ( ( A  e.  dom  card  /\ 
om  ~<_  A  /\  B  ~<  A )  ->  ( A  u.  B )  e.  dom  card )
11 ssun1 3313 . . . . . 6  |-  A  C_  ( A  u.  B
)
12 ssdomg 6875 . . . . . 6  |-  ( ( A  u.  B )  e.  dom  card  ->  ( A  C_  ( A  u.  B )  ->  A  ~<_  ( A  u.  B
) ) )
1310, 11, 12ee10 1372 . . . . 5  |-  ( ( A  e.  dom  card  /\ 
om  ~<_  A  /\  B  ~<  A )  ->  A  ~<_  ( A  u.  B
) )
14 undif1 3504 . . . . . 6  |-  ( ( A  \  B )  u.  B )  =  ( A  u.  B
)
15 ssnum 7634 . . . . . . . 8  |-  ( ( A  e.  dom  card  /\  ( A  \  B
)  C_  A )  ->  ( A  \  B
)  e.  dom  card )
161, 2, 15sylancl 646 . . . . . . 7  |-  ( ( A  e.  dom  card  /\ 
om  ~<_  A  /\  B  ~<  A )  ->  ( A  \  B )  e. 
dom  card )
17 uncdadom 7765 . . . . . . 7  |-  ( ( ( A  \  B
)  e.  dom  card  /\  B  e.  dom  card )  ->  ( ( A 
\  B )  u.  B )  ~<_  ( ( A  \  B )  +c  B ) )
1816, 8, 17syl2anc 645 . . . . . 6  |-  ( ( A  e.  dom  card  /\ 
om  ~<_  A  /\  B  ~<  A )  ->  (
( A  \  B
)  u.  B )  ~<_  ( ( A  \  B )  +c  B
) )
1914, 18syl5eqbrr 4031 . . . . 5  |-  ( ( A  e.  dom  card  /\ 
om  ~<_  A  /\  B  ~<  A )  ->  ( A  u.  B )  ~<_  ( ( A  \  B )  +c  B
) )
20 domtr 6882 . . . . 5  |-  ( ( A  ~<_  ( A  u.  B )  /\  ( A  u.  B )  ~<_  ( ( A  \  B )  +c  B
) )  ->  A  ~<_  ( ( A  \  B )  +c  B
) )
2113, 19, 20syl2anc 645 . . . 4  |-  ( ( A  e.  dom  card  /\ 
om  ~<_  A  /\  B  ~<  A )  ->  A  ~<_  ( ( A  \  B )  +c  B
) )
22 simp3 962 . . . . . . 7  |-  ( ( A  e.  dom  card  /\ 
om  ~<_  A  /\  B  ~<  A )  ->  B  ~<  A )
23 sdomdom 6857 . . . . . . . . 9  |-  ( ( A  \  B ) 
~<  B  ->  ( A 
\  B )  ~<_  B )
24 cdadom1 7780 . . . . . . . . 9  |-  ( ( A  \  B )  ~<_  B  ->  ( ( A  \  B )  +c  B )  ~<_  ( B  +c  B ) )
2523, 24syl 17 . . . . . . . 8  |-  ( ( A  \  B ) 
~<  B  ->  ( ( A  \  B )  +c  B )  ~<_  ( B  +c  B ) )
26 domtr 6882 . . . . . . . . . . 11  |-  ( ( A  ~<_  ( ( A 
\  B )  +c  B )  /\  (
( A  \  B
)  +c  B )  ~<_  ( B  +c  B
) )  ->  A  ~<_  ( B  +c  B
) )
2726ex 425 . . . . . . . . . 10  |-  ( A  ~<_  ( ( A  \  B )  +c  B
)  ->  ( (
( A  \  B
)  +c  B )  ~<_  ( B  +c  B
)  ->  A  ~<_  ( B  +c  B ) ) )
2821, 27syl 17 . . . . . . . . 9  |-  ( ( A  e.  dom  card  /\ 
om  ~<_  A  /\  B  ~<  A )  ->  (
( ( A  \  B )  +c  B
)  ~<_  ( B  +c  B )  ->  A  ~<_  ( B  +c  B
) ) )
29 simp2 961 . . . . . . . . . . . 12  |-  ( ( A  e.  dom  card  /\ 
om  ~<_  A  /\  B  ~<  A )  ->  om  ~<_  A )
30 domtr 6882 . . . . . . . . . . . . 13  |-  ( ( om  ~<_  A  /\  A  ~<_  ( B  +c  B
) )  ->  om  ~<_  ( B  +c  B ) )
3130ex 425 . . . . . . . . . . . 12  |-  ( om  ~<_  A  ->  ( A  ~<_  ( B  +c  B
)  ->  om  ~<_  ( B  +c  B ) ) )
3229, 31syl 17 . . . . . . . . . . 11  |-  ( ( A  e.  dom  card  /\ 
om  ~<_  A  /\  B  ~<  A )  ->  ( A  ~<_  ( B  +c  B )  ->  om  ~<_  ( B  +c  B ) ) )
33 cdainf 7786 . . . . . . . . . . . . 13  |-  ( om  ~<_  B  <->  om  ~<_  ( B  +c  B ) )
3433biimpri 199 . . . . . . . . . . . 12  |-  ( om  ~<_  ( B  +c  B
)  ->  om  ~<_  B )
35 domrefg 6864 . . . . . . . . . . . . 13  |-  ( B  e.  dom  card  ->  B  ~<_  B )
36 infcdaabs 7800 . . . . . . . . . . . . . . 15  |-  ( ( B  e.  dom  card  /\ 
om  ~<_  B  /\  B  ~<_  B )  ->  ( B  +c  B )  ~~  B )
37363com23 1162 . . . . . . . . . . . . . 14  |-  ( ( B  e.  dom  card  /\  B  ~<_  B  /\  om  ~<_  B )  ->  ( B  +c  B )  ~~  B )
38373expia 1158 . . . . . . . . . . . . 13  |-  ( ( B  e.  dom  card  /\  B  ~<_  B )  -> 
( om  ~<_  B  -> 
( B  +c  B
)  ~~  B )
)
3935, 38mpdan 652 . . . . . . . . . . . 12  |-  ( B  e.  dom  card  ->  ( om  ~<_  B  ->  ( B  +c  B )  ~~  B ) )
408, 34, 39syl2im 36 . . . . . . . . . . 11  |-  ( ( A  e.  dom  card  /\ 
om  ~<_  A  /\  B  ~<  A )  ->  ( om 
~<_  ( B  +c  B
)  ->  ( B  +c  B )  ~~  B
) )
4132, 40syld 42 . . . . . . . . . 10  |-  ( ( A  e.  dom  card  /\ 
om  ~<_  A  /\  B  ~<  A )  ->  ( A  ~<_  ( B  +c  B )  ->  ( B  +c  B )  ~~  B ) )
42 domen2 6972 . . . . . . . . . . 11  |-  ( ( B  +c  B ) 
~~  B  ->  ( A  ~<_  ( B  +c  B )  <->  A  ~<_  B ) )
4342biimpcd 217 . . . . . . . . . 10  |-  ( A  ~<_  ( B  +c  B
)  ->  ( ( B  +c  B )  ~~  B  ->  A  ~<_  B ) )
4441, 43sylcom 27 . . . . . . . . 9  |-  ( ( A  e.  dom  card  /\ 
om  ~<_  A  /\  B  ~<  A )  ->  ( A  ~<_  ( B  +c  B )  ->  A  ~<_  B ) )
4528, 44syld 42 . . . . . . . 8  |-  ( ( A  e.  dom  card  /\ 
om  ~<_  A  /\  B  ~<  A )  ->  (
( ( A  \  B )  +c  B
)  ~<_  ( B  +c  B )  ->  A  ~<_  B ) )
46 domnsym 6955 . . . . . . . 8  |-  ( A  ~<_  B  ->  -.  B  ~<  A )
4725, 45, 46syl56 32 . . . . . . 7  |-  ( ( A  e.  dom  card  /\ 
om  ~<_  A  /\  B  ~<  A )  ->  (
( A  \  B
)  ~<  B  ->  -.  B  ~<  A ) )
4822, 47mt2d 111 . . . . . 6  |-  ( ( A  e.  dom  card  /\ 
om  ~<_  A  /\  B  ~<  A )  ->  -.  ( A  \  B ) 
~<  B )
49 domtri2 7590 . . . . . . 7  |-  ( ( B  e.  dom  card  /\  ( A  \  B
)  e.  dom  card )  ->  ( B  ~<_  ( A  \  B )  <->  -.  ( A  \  B
)  ~<  B ) )
508, 16, 49syl2anc 645 . . . . . 6  |-  ( ( A  e.  dom  card  /\ 
om  ~<_  A  /\  B  ~<  A )  ->  ( B  ~<_  ( A  \  B )  <->  -.  ( A  \  B )  ~<  B ) )
5148, 50mpbird 225 . . . . 5  |-  ( ( A  e.  dom  card  /\ 
om  ~<_  A  /\  B  ~<  A )  ->  B  ~<_  ( A  \  B ) )
52 cdadom2 7781 . . . . 5  |-  ( B  ~<_  ( A  \  B
)  ->  ( ( A  \  B )  +c  B )  ~<_  ( ( A  \  B )  +c  ( A  \  B ) ) )
5351, 52syl 17 . . . 4  |-  ( ( A  e.  dom  card  /\ 
om  ~<_  A  /\  B  ~<  A )  ->  (
( A  \  B
)  +c  B )  ~<_  ( ( A  \  B )  +c  ( A  \  B ) ) )
54 domtr 6882 . . . 4  |-  ( ( A  ~<_  ( ( A 
\  B )  +c  B )  /\  (
( A  \  B
)  +c  B )  ~<_  ( ( A  \  B )  +c  ( A  \  B ) ) )  ->  A  ~<_  ( ( A  \  B )  +c  ( A  \  B ) ) )
5521, 53, 54syl2anc 645 . . 3  |-  ( ( A  e.  dom  card  /\ 
om  ~<_  A  /\  B  ~<  A )  ->  A  ~<_  ( ( A  \  B )  +c  ( A  \  B ) ) )
56 domtr 6882 . . . . . 6  |-  ( ( om  ~<_  A  /\  A  ~<_  ( ( A  \  B )  +c  ( A  \  B ) ) )  ->  om  ~<_  ( ( A  \  B )  +c  ( A  \  B ) ) )
5729, 55, 56syl2anc 645 . . . . 5  |-  ( ( A  e.  dom  card  /\ 
om  ~<_  A  /\  B  ~<  A )  ->  om  ~<_  ( ( A  \  B )  +c  ( A  \  B ) ) )
58 cdainf 7786 . . . . 5  |-  ( om  ~<_  ( A  \  B
)  <->  om  ~<_  ( ( A 
\  B )  +c  ( A  \  B
) ) )
5957, 58sylibr 205 . . . 4  |-  ( ( A  e.  dom  card  /\ 
om  ~<_  A  /\  B  ~<  A )  ->  om  ~<_  ( A 
\  B ) )
60 domrefg 6864 . . . . 5  |-  ( ( A  \  B )  e.  dom  card  ->  ( A  \  B )  ~<_  ( A  \  B
) )
6116, 60syl 17 . . . 4  |-  ( ( A  e.  dom  card  /\ 
om  ~<_  A  /\  B  ~<  A )  ->  ( A  \  B )  ~<_  ( A  \  B ) )
62 infcdaabs 7800 . . . 4  |-  ( ( ( A  \  B
)  e.  dom  card  /\ 
om  ~<_  ( A  \  B )  /\  ( A  \  B )  ~<_  ( A  \  B ) )  ->  ( ( A  \  B )  +c  ( A  \  B
) )  ~~  ( A  \  B ) )
6316, 59, 61, 62syl3anc 1187 . . 3  |-  ( ( A  e.  dom  card  /\ 
om  ~<_  A  /\  B  ~<  A )  ->  (
( A  \  B
)  +c  ( A 
\  B ) ) 
~~  ( A  \  B ) )
64 domentr 6888 . . 3  |-  ( ( A  ~<_  ( ( A 
\  B )  +c  ( A  \  B
) )  /\  (
( A  \  B
)  +c  ( A 
\  B ) ) 
~~  ( A  \  B ) )  ->  A  ~<_  ( A  \  B ) )
6555, 63, 64syl2anc 645 . 2  |-  ( ( A  e.  dom  card  /\ 
om  ~<_  A  /\  B  ~<  A )  ->  A  ~<_  ( A  \  B ) )
66 sbth 6949 . 2  |-  ( ( ( A  \  B
)  ~<_  A  /\  A  ~<_  ( A  \  B ) )  ->  ( A  \  B )  ~~  A
)
674, 65, 66syl2anc 645 1  |-  ( ( A  e.  dom  card  /\ 
om  ~<_  A  /\  B  ~<  A )  ->  ( A  \  B )  ~~  A )
Colors of variables: wff set class
Syntax hints:   -. wn 5    -> wi 6    <-> wb 178    /\ w3a 939    e. wcel 1621    \ cdif 3124    u. cun 3125    C_ wss 3127   class class class wbr 3997   omcom 4628   dom cdm 4661  (class class class)co 5792    ~~ cen 6828    ~<_ cdom 6829    ~< csdm 6830   cardccrd 7536    +c ccda 7761
This theorem is referenced by:  infdif2  7804  alephsuc3  8170  aleph1irr  12486
This theorem was proved from axioms:  ax-1 7  ax-2 8  ax-3 9  ax-mp 10  ax-5 1533  ax-6 1534  ax-7 1535  ax-gen 1536  ax-8 1623  ax-11 1624  ax-13 1625  ax-14 1626  ax-17 1628  ax-12o 1664  ax-10 1678  ax-9 1684  ax-4 1692  ax-16 1927  ax-ext 2239  ax-rep 4105  ax-sep 4115  ax-nul 4123  ax-pow 4160  ax-pr 4186  ax-un 4484  ax-inf2 7310
This theorem depends on definitions:  df-bi 179  df-or 361  df-an 362  df-3or 940  df-3an 941  df-tru 1315  df-ex 1538  df-nf 1540  df-sb 1884  df-eu 2122  df-mo 2123  df-clab 2245  df-cleq 2251  df-clel 2254  df-nfc 2383  df-ne 2423  df-ral 2523  df-rex 2524  df-reu 2525  df-rmo 2526  df-rab 2527  df-v 2765  df-sbc 2967  df-csb 3057  df-dif 3130  df-un 3132  df-in 3134  df-ss 3141  df-pss 3143  df-nul 3431  df-if 3540  df-pw 3601  df-sn 3620  df-pr 3621  df-tp 3622  df-op 3623  df-uni 3802  df-int 3837  df-iun 3881  df-br 3998  df-opab 4052  df-mpt 4053  df-tr 4088  df-eprel 4277  df-id 4281  df-po 4286  df-so 4287  df-fr 4324  df-se 4325  df-we 4326  df-ord 4367  df-on 4368  df-lim 4369  df-suc 4370  df-om 4629  df-xp 4675  df-rel 4676  df-cnv 4677  df-co 4678  df-dm 4679  df-rn 4680  df-res 4681  df-ima 4682  df-fun 4683  df-fn 4684  df-f 4685  df-f1 4686  df-fo 4687  df-f1o 4688  df-fv 4689  df-isom 4690  df-ov 5795  df-oprab 5796  df-mpt2 5797  df-1st 6056  df-2nd 6057  df-iota 6225  df-riota 6272  df-recs 6356  df-rdg 6391  df-1o 6447  df-2o 6448  df-oadd 6451  df-er 6628  df-en 6832  df-dom 6833  df-sdom 6834  df-fin 6835  df-oi 7193  df-card 7540  df-cda 7762
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