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Theorem oa00 6557
Description: An ordinal sum is zero iff both of its arguments are zero. (Contributed by NM, 6-Dec-2004.)
Assertion
Ref Expression
oa00  |-  ( ( A  e.  On  /\  B  e.  On )  ->  ( ( A  +o  B )  =  (/)  <->  ( A  =  (/)  /\  B  =  (/) ) ) )

Proof of Theorem oa00
StepHypRef Expression
1 on0eln0 4447 . . . . . . 7  |-  ( A  e.  On  ->  ( (/) 
e.  A  <->  A  =/=  (/) ) )
21adantr 451 . . . . . 6  |-  ( ( A  e.  On  /\  B  e.  On )  ->  ( (/)  e.  A  <->  A  =/=  (/) ) )
3 oaword1 6550 . . . . . . 7  |-  ( ( A  e.  On  /\  B  e.  On )  ->  A  C_  ( A  +o  B ) )
43sseld 3179 . . . . . 6  |-  ( ( A  e.  On  /\  B  e.  On )  ->  ( (/)  e.  A  -> 
(/)  e.  ( A  +o  B ) ) )
52, 4sylbird 226 . . . . 5  |-  ( ( A  e.  On  /\  B  e.  On )  ->  ( A  =/=  (/)  ->  (/)  e.  ( A  +o  B ) ) )
6 ne0i 3461 . . . . 5  |-  ( (/)  e.  ( A  +o  B
)  ->  ( A  +o  B )  =/=  (/) )
75, 6syl6 29 . . . 4  |-  ( ( A  e.  On  /\  B  e.  On )  ->  ( A  =/=  (/)  ->  ( A  +o  B )  =/=  (/) ) )
87necon4d 2509 . . 3  |-  ( ( A  e.  On  /\  B  e.  On )  ->  ( ( A  +o  B )  =  (/)  ->  A  =  (/) ) )
9 on0eln0 4447 . . . . . . 7  |-  ( B  e.  On  ->  ( (/) 
e.  B  <->  B  =/=  (/) ) )
109adantl 452 . . . . . 6  |-  ( ( A  e.  On  /\  B  e.  On )  ->  ( (/)  e.  B  <->  B  =/=  (/) ) )
11 0elon 4445 . . . . . . . 8  |-  (/)  e.  On
12 oaord 6545 . . . . . . . 8  |-  ( (
(/)  e.  On  /\  B  e.  On  /\  A  e.  On )  ->  ( (/) 
e.  B  <->  ( A  +o  (/) )  e.  ( A  +o  B ) ) )
1311, 12mp3an1 1264 . . . . . . 7  |-  ( ( B  e.  On  /\  A  e.  On )  ->  ( (/)  e.  B  <->  ( A  +o  (/) )  e.  ( A  +o  B
) ) )
1413ancoms 439 . . . . . 6  |-  ( ( A  e.  On  /\  B  e.  On )  ->  ( (/)  e.  B  <->  ( A  +o  (/) )  e.  ( A  +o  B
) ) )
1510, 14bitr3d 246 . . . . 5  |-  ( ( A  e.  On  /\  B  e.  On )  ->  ( B  =/=  (/)  <->  ( A  +o  (/) )  e.  ( A  +o  B ) ) )
16 ne0i 3461 . . . . 5  |-  ( ( A  +o  (/) )  e.  ( A  +o  B
)  ->  ( A  +o  B )  =/=  (/) )
1715, 16syl6bi 219 . . . 4  |-  ( ( A  e.  On  /\  B  e.  On )  ->  ( B  =/=  (/)  ->  ( A  +o  B )  =/=  (/) ) )
1817necon4d 2509 . . 3  |-  ( ( A  e.  On  /\  B  e.  On )  ->  ( ( A  +o  B )  =  (/)  ->  B  =  (/) ) )
198, 18jcad 519 . 2  |-  ( ( A  e.  On  /\  B  e.  On )  ->  ( ( A  +o  B )  =  (/)  ->  ( A  =  (/)  /\  B  =  (/) ) ) )
20 oveq12 5867 . . 3  |-  ( ( A  =  (/)  /\  B  =  (/) )  ->  ( A  +o  B )  =  ( (/)  +o  (/) ) )
21 oa0 6515 . . . 4  |-  ( (/)  e.  On  ->  ( (/)  +o  (/) )  =  (/) )
2211, 21ax-mp 8 . . 3  |-  ( (/)  +o  (/) )  =  (/)
2320, 22syl6eq 2331 . 2  |-  ( ( A  =  (/)  /\  B  =  (/) )  ->  ( A  +o  B )  =  (/) )
2419, 23impbid1 194 1  |-  ( ( A  e.  On  /\  B  e.  On )  ->  ( ( A  +o  B )  =  (/)  <->  ( A  =  (/)  /\  B  =  (/) ) ) )
Colors of variables: wff set class
Syntax hints:    -> wi 4    <-> wb 176    /\ wa 358    = wceq 1623    e. wcel 1684    =/= wne 2446   (/)c0 3455   Oncon0 4392  (class class class)co 5858    +o coa 6476
This theorem is referenced by:  oalimcl  6558  oeoa  6595
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-3 7  ax-mp 8  ax-gen 1533  ax-5 1544  ax-17 1603  ax-9 1635  ax-8 1643  ax-13 1686  ax-14 1688  ax-6 1703  ax-7 1708  ax-11 1715  ax-12 1866  ax-ext 2264  ax-rep 4131  ax-sep 4141  ax-nul 4149  ax-pow 4188  ax-pr 4214  ax-un 4512
This theorem depends on definitions:  df-bi 177  df-or 359  df-an 360  df-3or 935  df-3an 936  df-tru 1310  df-ex 1529  df-nf 1532  df-sb 1630  df-eu 2147  df-mo 2148  df-clab 2270  df-cleq 2276  df-clel 2279  df-nfc 2408  df-ne 2448  df-ral 2548  df-rex 2549  df-reu 2550  df-rab 2552  df-v 2790  df-sbc 2992  df-csb 3082  df-dif 3155  df-un 3157  df-in 3159  df-ss 3166  df-pss 3168  df-nul 3456  df-if 3566  df-pw 3627  df-sn 3646  df-pr 3647  df-tp 3648  df-op 3649  df-uni 3828  df-iun 3907  df-br 4024  df-opab 4078  df-mpt 4079  df-tr 4114  df-eprel 4305  df-id 4309  df-po 4314  df-so 4315  df-fr 4352  df-we 4354  df-ord 4395  df-on 4396  df-lim 4397  df-suc 4398  df-om 4657  df-xp 4695  df-rel 4696  df-cnv 4697  df-co 4698  df-dm 4699  df-rn 4700  df-res 4701  df-ima 4702  df-iota 5219  df-fun 5257  df-fn 5258  df-f 5259  df-f1 5260  df-fo 5261  df-f1o 5262  df-fv 5263  df-ov 5861  df-oprab 5862  df-mpt2 5863  df-recs 6388  df-rdg 6423  df-oadd 6483
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