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Theorem nn0le2is012 9157
Description: A nonnegative integer which is less than or equal to 2 is either 0 or 1 or 2. (Contributed by AV, 16-Mar-2019.)
Assertion
Ref Expression
nn0le2is012  |-  ( ( N  e.  NN0  /\  N  <_  2 )  -> 
( N  =  0  \/  N  =  1  \/  N  =  2 ) )

Proof of Theorem nn0le2is012
StepHypRef Expression
1 nn0z 9098 . . . 4  |-  ( N  e.  NN0  ->  N  e.  ZZ )
2 2z 9106 . . . 4  |-  2  e.  ZZ
3 zleloe 9125 . . . 4  |-  ( ( N  e.  ZZ  /\  2  e.  ZZ )  ->  ( N  <_  2  <->  ( N  <  2  \/  N  =  2 ) ) )
41, 2, 3sylancl 410 . . 3  |-  ( N  e.  NN0  ->  ( N  <_  2  <->  ( N  <  2  \/  N  =  2 ) ) )
5 zltlem1 9135 . . . . . . . . 9  |-  ( ( N  e.  ZZ  /\  2  e.  ZZ )  ->  ( N  <  2  <->  N  <_  ( 2  -  1 ) ) )
61, 2, 5sylancl 410 . . . . . . . 8  |-  ( N  e.  NN0  ->  ( N  <  2  <->  N  <_  ( 2  -  1 ) ) )
7 2m1e1 8862 . . . . . . . . . 10  |-  ( 2  -  1 )  =  1
87a1i 9 . . . . . . . . 9  |-  ( N  e.  NN0  ->  ( 2  -  1 )  =  1 )
98breq2d 3949 . . . . . . . 8  |-  ( N  e.  NN0  ->  ( N  <_  ( 2  -  1 )  <->  N  <_  1 ) )
106, 9bitrd 187 . . . . . . 7  |-  ( N  e.  NN0  ->  ( N  <  2  <->  N  <_  1 ) )
11 1z 9104 . . . . . . . . 9  |-  1  e.  ZZ
12 zleloe 9125 . . . . . . . . 9  |-  ( ( N  e.  ZZ  /\  1  e.  ZZ )  ->  ( N  <_  1  <->  ( N  <  1  \/  N  =  1 ) ) )
131, 11, 12sylancl 410 . . . . . . . 8  |-  ( N  e.  NN0  ->  ( N  <_  1  <->  ( N  <  1  \/  N  =  1 ) ) )
14 nn0lt10b 9155 . . . . . . . . . . . 12  |-  ( N  e.  NN0  ->  ( N  <  1  <->  N  = 
0 ) )
15 3mix1 1151 . . . . . . . . . . . 12  |-  ( N  =  0  ->  ( N  =  0  \/  N  =  1  \/  N  =  2 ) )
1614, 15syl6bi 162 . . . . . . . . . . 11  |-  ( N  e.  NN0  ->  ( N  <  1  ->  ( N  =  0  \/  N  =  1  \/  N  =  2 ) ) )
1716com12 30 . . . . . . . . . 10  |-  ( N  <  1  ->  ( N  e.  NN0  ->  ( N  =  0  \/  N  =  1  \/  N  =  2 ) ) )
18 3mix2 1152 . . . . . . . . . . 11  |-  ( N  =  1  ->  ( N  =  0  \/  N  =  1  \/  N  =  2 ) )
1918a1d 22 . . . . . . . . . 10  |-  ( N  =  1  ->  ( N  e.  NN0  ->  ( N  =  0  \/  N  =  1  \/  N  =  2 ) ) )
2017, 19jaoi 706 . . . . . . . . 9  |-  ( ( N  <  1  \/  N  =  1 )  ->  ( N  e. 
NN0  ->  ( N  =  0  \/  N  =  1  \/  N  =  2 ) ) )
2120com12 30 . . . . . . . 8  |-  ( N  e.  NN0  ->  ( ( N  <  1  \/  N  =  1 )  ->  ( N  =  0  \/  N  =  1  \/  N  =  2 ) ) )
2213, 21sylbid 149 . . . . . . 7  |-  ( N  e.  NN0  ->  ( N  <_  1  ->  ( N  =  0  \/  N  =  1  \/  N  =  2 ) ) )
2310, 22sylbid 149 . . . . . 6  |-  ( N  e.  NN0  ->  ( N  <  2  ->  ( N  =  0  \/  N  =  1  \/  N  =  2 ) ) )
2423com12 30 . . . . 5  |-  ( N  <  2  ->  ( N  e.  NN0  ->  ( N  =  0  \/  N  =  1  \/  N  =  2 ) ) )
25 3mix3 1153 . . . . . 6  |-  ( N  =  2  ->  ( N  =  0  \/  N  =  1  \/  N  =  2 ) )
2625a1d 22 . . . . 5  |-  ( N  =  2  ->  ( N  e.  NN0  ->  ( N  =  0  \/  N  =  1  \/  N  =  2 ) ) )
2724, 26jaoi 706 . . . 4  |-  ( ( N  <  2  \/  N  =  2 )  ->  ( N  e. 
NN0  ->  ( N  =  0  \/  N  =  1  \/  N  =  2 ) ) )
2827com12 30 . . 3  |-  ( N  e.  NN0  ->  ( ( N  <  2  \/  N  =  2 )  ->  ( N  =  0  \/  N  =  1  \/  N  =  2 ) ) )
294, 28sylbid 149 . 2  |-  ( N  e.  NN0  ->  ( N  <_  2  ->  ( N  =  0  \/  N  =  1  \/  N  =  2 ) ) )
3029imp 123 1  |-  ( ( N  e.  NN0  /\  N  <_  2 )  -> 
( N  =  0  \/  N  =  1  \/  N  =  2 ) )
Colors of variables: wff set class
Syntax hints:    -> wi 4    /\ wa 103    <-> wb 104    \/ wo 698    \/ w3o 962    = wceq 1332    e. wcel 1481   class class class wbr 3937  (class class class)co 5782   0cc0 7644   1c1 7645    < clt 7824    <_ cle 7825    - cmin 7957   2c2 8795   NN0cn0 9001   ZZcz 9078
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-in1 604  ax-in2 605  ax-io 699  ax-5 1424  ax-7 1425  ax-gen 1426  ax-ie1 1470  ax-ie2 1471  ax-8 1483  ax-10 1484  ax-11 1485  ax-i12 1486  ax-bndl 1487  ax-4 1488  ax-13 1492  ax-14 1493  ax-17 1507  ax-i9 1511  ax-ial 1515  ax-i5r 1516  ax-ext 2122  ax-sep 4054  ax-pow 4106  ax-pr 4139  ax-un 4363  ax-setind 4460  ax-cnex 7735  ax-resscn 7736  ax-1cn 7737  ax-1re 7738  ax-icn 7739  ax-addcl 7740  ax-addrcl 7741  ax-mulcl 7742  ax-addcom 7744  ax-addass 7746  ax-distr 7748  ax-i2m1 7749  ax-0lt1 7750  ax-0id 7752  ax-rnegex 7753  ax-cnre 7755  ax-pre-ltirr 7756  ax-pre-ltwlin 7757  ax-pre-lttrn 7758  ax-pre-apti 7759  ax-pre-ltadd 7760
This theorem depends on definitions:  df-bi 116  df-3or 964  df-3an 965  df-tru 1335  df-fal 1338  df-nf 1438  df-sb 1737  df-eu 2003  df-mo 2004  df-clab 2127  df-cleq 2133  df-clel 2136  df-nfc 2271  df-ne 2310  df-nel 2405  df-ral 2422  df-rex 2423  df-reu 2424  df-rab 2426  df-v 2691  df-sbc 2914  df-dif 3078  df-un 3080  df-in 3082  df-ss 3089  df-pw 3517  df-sn 3538  df-pr 3539  df-op 3541  df-uni 3745  df-int 3780  df-br 3938  df-opab 3998  df-id 4223  df-xp 4553  df-rel 4554  df-cnv 4555  df-co 4556  df-dm 4557  df-iota 5096  df-fun 5133  df-fv 5139  df-riota 5738  df-ov 5785  df-oprab 5786  df-mpo 5787  df-pnf 7826  df-mnf 7827  df-xr 7828  df-ltxr 7829  df-le 7830  df-sub 7959  df-neg 7960  df-inn 8745  df-2 8803  df-n0 9002  df-z 9079
This theorem is referenced by:  xnn0le2is012  9679
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