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Theorem ltpnf 9716
Description: Any (finite) real is less than plus infinity. (Contributed by NM, 14-Oct-2005.)
Assertion
Ref Expression
ltpnf  |-  ( A  e.  RR  ->  A  < +oo )

Proof of Theorem ltpnf
StepHypRef Expression
1 eqid 2165 . . . 4  |- +oo  = +oo
2 orc 702 . . . 4  |-  ( ( A  e.  RR  /\ +oo  = +oo )  -> 
( ( A  e.  RR  /\ +oo  = +oo )  \/  ( A  = -oo  /\ +oo  e.  RR ) ) )
31, 2mpan2 422 . . 3  |-  ( A  e.  RR  ->  (
( A  e.  RR  /\ +oo  = +oo )  \/  ( A  = -oo  /\ +oo  e.  RR ) ) )
43olcd 724 . 2  |-  ( A  e.  RR  ->  (
( ( ( A  e.  RR  /\ +oo  e.  RR )  /\  A  <RR +oo )  \/  ( A  = -oo  /\ +oo  = +oo ) )  \/  ( ( A  e.  RR  /\ +oo  = +oo )  \/  ( A  = -oo  /\ +oo  e.  RR ) ) ) )
5 rexr 7944 . . 3  |-  ( A  e.  RR  ->  A  e.  RR* )
6 pnfxr 7951 . . 3  |- +oo  e.  RR*
7 ltxr 9711 . . 3  |-  ( ( A  e.  RR*  /\ +oo  e.  RR* )  ->  ( A  < +oo  <->  ( ( ( ( A  e.  RR  /\ +oo  e.  RR )  /\  A  <RR +oo )  \/  ( A  = -oo  /\ +oo  = +oo ) )  \/  ( ( A  e.  RR  /\ +oo  = +oo )  \/  ( A  = -oo  /\ +oo  e.  RR ) ) ) ) )
85, 6, 7sylancl 410 . 2  |-  ( A  e.  RR  ->  ( A  < +oo  <->  ( ( ( ( A  e.  RR  /\ +oo  e.  RR )  /\  A  <RR +oo )  \/  ( A  = -oo  /\ +oo  = +oo ) )  \/  ( ( A  e.  RR  /\ +oo  = +oo )  \/  ( A  = -oo  /\ +oo  e.  RR ) ) ) ) )
94, 8mpbird 166 1  |-  ( A  e.  RR  ->  A  < +oo )
Colors of variables: wff set class
Syntax hints:    -> wi 4    /\ wa 103    <-> wb 104    \/ wo 698    = wceq 1343    e. wcel 2136   class class class wbr 3982   RRcr 7752    <RR cltrr 7757   +oocpnf 7930   -oocmnf 7931   RR*cxr 7932    < clt 7933
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-io 699  ax-5 1435  ax-7 1436  ax-gen 1437  ax-ie1 1481  ax-ie2 1482  ax-8 1492  ax-10 1493  ax-11 1494  ax-i12 1495  ax-bndl 1497  ax-4 1498  ax-17 1514  ax-i9 1518  ax-ial 1522  ax-i5r 1523  ax-13 2138  ax-14 2139  ax-ext 2147  ax-sep 4100  ax-pow 4153  ax-pr 4187  ax-un 4411  ax-cnex 7844
This theorem depends on definitions:  df-bi 116  df-3an 970  df-tru 1346  df-nf 1449  df-sb 1751  df-eu 2017  df-mo 2018  df-clab 2152  df-cleq 2158  df-clel 2161  df-nfc 2297  df-ral 2449  df-rex 2450  df-v 2728  df-un 3120  df-in 3122  df-ss 3129  df-pw 3561  df-sn 3582  df-pr 3583  df-op 3585  df-uni 3790  df-br 3983  df-opab 4044  df-xp 4610  df-pnf 7935  df-xr 7937  df-ltxr 7938
This theorem is referenced by:  ltpnfd  9717  0ltpnf  9718  xrlttr  9731  xrltso  9732  xrlttri3  9733  nltpnft  9750  npnflt  9751  xrrebnd  9755  xrre  9756  xltnegi  9771  xltadd1  9812  xposdif  9818  elioc2  9872  elicc2  9874  ioomax  9884  ioopos  9886  elioopnf  9903  elicopnf  9905  qbtwnxr  10193  dfrp2  10199  filtinf  10705  xrmaxltsup  11199  fprodge0  11578  fprodge1  11580  xblss2ps  13044
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