MPE Home Metamath Proof Explorer < Previous   Next >
Nearby theorems
Mirrors  >  Home  >  MPE Home  >  Th. List  >  xmulval Structured version   Visualization version   Unicode version

Theorem xmulval 12056
Description: Value of the extended real multiplication operation. (Contributed by Mario Carneiro, 20-Aug-2015.)
Assertion
Ref Expression
xmulval  |-  ( ( A  e.  RR*  /\  B  e.  RR* )  ->  ( A xe B )  =  if ( ( A  =  0  \/  B  =  0 ) ,  0 ,  if ( ( ( ( 0  <  B  /\  A  = +oo )  \/  ( B  <  0  /\  A  = -oo ) )  \/  (
( 0  <  A  /\  B  = +oo )  \/  ( A  <  0  /\  B  = -oo ) ) ) , +oo ,  if ( ( ( ( 0  <  B  /\  A  = -oo )  \/  ( B  <  0  /\  A  = +oo ) )  \/  (
( 0  <  A  /\  B  = -oo )  \/  ( A  <  0  /\  B  = +oo ) ) ) , -oo ,  ( A  x.  B ) ) ) ) )

Proof of Theorem xmulval
Dummy variables  x  y are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 simpl 473 . . . . 5  |-  ( ( x  =  A  /\  y  =  B )  ->  x  =  A )
21eqeq1d 2624 . . . 4  |-  ( ( x  =  A  /\  y  =  B )  ->  ( x  =  0  <-> 
A  =  0 ) )
3 simpr 477 . . . . 5  |-  ( ( x  =  A  /\  y  =  B )  ->  y  =  B )
43eqeq1d 2624 . . . 4  |-  ( ( x  =  A  /\  y  =  B )  ->  ( y  =  0  <-> 
B  =  0 ) )
52, 4orbi12d 746 . . 3  |-  ( ( x  =  A  /\  y  =  B )  ->  ( ( x  =  0  \/  y  =  0 )  <->  ( A  =  0  \/  B  =  0 ) ) )
63breq2d 4665 . . . . . . 7  |-  ( ( x  =  A  /\  y  =  B )  ->  ( 0  <  y  <->  0  <  B ) )
71eqeq1d 2624 . . . . . . 7  |-  ( ( x  =  A  /\  y  =  B )  ->  ( x  = +oo  <->  A  = +oo ) )
86, 7anbi12d 747 . . . . . 6  |-  ( ( x  =  A  /\  y  =  B )  ->  ( ( 0  < 
y  /\  x  = +oo )  <->  ( 0  < 
B  /\  A  = +oo ) ) )
93breq1d 4663 . . . . . . 7  |-  ( ( x  =  A  /\  y  =  B )  ->  ( y  <  0  <->  B  <  0 ) )
101eqeq1d 2624 . . . . . . 7  |-  ( ( x  =  A  /\  y  =  B )  ->  ( x  = -oo  <->  A  = -oo ) )
119, 10anbi12d 747 . . . . . 6  |-  ( ( x  =  A  /\  y  =  B )  ->  ( ( y  <  0  /\  x  = -oo )  <->  ( B  <  0  /\  A  = -oo ) ) )
128, 11orbi12d 746 . . . . 5  |-  ( ( x  =  A  /\  y  =  B )  ->  ( ( ( 0  <  y  /\  x  = +oo )  \/  (
y  <  0  /\  x  = -oo )
)  <->  ( ( 0  <  B  /\  A  = +oo )  \/  ( B  <  0  /\  A  = -oo ) ) ) )
131breq2d 4665 . . . . . . 7  |-  ( ( x  =  A  /\  y  =  B )  ->  ( 0  <  x  <->  0  <  A ) )
143eqeq1d 2624 . . . . . . 7  |-  ( ( x  =  A  /\  y  =  B )  ->  ( y  = +oo  <->  B  = +oo ) )
1513, 14anbi12d 747 . . . . . 6  |-  ( ( x  =  A  /\  y  =  B )  ->  ( ( 0  < 
x  /\  y  = +oo )  <->  ( 0  < 
A  /\  B  = +oo ) ) )
161breq1d 4663 . . . . . . 7  |-  ( ( x  =  A  /\  y  =  B )  ->  ( x  <  0  <->  A  <  0 ) )
173eqeq1d 2624 . . . . . . 7  |-  ( ( x  =  A  /\  y  =  B )  ->  ( y  = -oo  <->  B  = -oo ) )
1816, 17anbi12d 747 . . . . . 6  |-  ( ( x  =  A  /\  y  =  B )  ->  ( ( x  <  0  /\  y  = -oo )  <->  ( A  <  0  /\  B  = -oo ) ) )
1915, 18orbi12d 746 . . . . 5  |-  ( ( x  =  A  /\  y  =  B )  ->  ( ( ( 0  <  x  /\  y  = +oo )  \/  (
x  <  0  /\  y  = -oo )
)  <->  ( ( 0  <  A  /\  B  = +oo )  \/  ( A  <  0  /\  B  = -oo ) ) ) )
2012, 19orbi12d 746 . . . 4  |-  ( ( x  =  A  /\  y  =  B )  ->  ( ( ( ( 0  <  y  /\  x  = +oo )  \/  ( y  <  0  /\  x  = -oo ) )  \/  (
( 0  <  x  /\  y  = +oo )  \/  ( x  <  0  /\  y  = -oo ) ) )  <-> 
( ( ( 0  <  B  /\  A  = +oo )  \/  ( B  <  0  /\  A  = -oo ) )  \/  ( ( 0  < 
A  /\  B  = +oo )  \/  ( A  <  0  /\  B  = -oo ) ) ) ) )
216, 10anbi12d 747 . . . . . . 7  |-  ( ( x  =  A  /\  y  =  B )  ->  ( ( 0  < 
y  /\  x  = -oo )  <->  ( 0  < 
B  /\  A  = -oo ) ) )
229, 7anbi12d 747 . . . . . . 7  |-  ( ( x  =  A  /\  y  =  B )  ->  ( ( y  <  0  /\  x  = +oo )  <->  ( B  <  0  /\  A  = +oo ) ) )
2321, 22orbi12d 746 . . . . . 6  |-  ( ( x  =  A  /\  y  =  B )  ->  ( ( ( 0  <  y  /\  x  = -oo )  \/  (
y  <  0  /\  x  = +oo )
)  <->  ( ( 0  <  B  /\  A  = -oo )  \/  ( B  <  0  /\  A  = +oo ) ) ) )
2413, 17anbi12d 747 . . . . . . 7  |-  ( ( x  =  A  /\  y  =  B )  ->  ( ( 0  < 
x  /\  y  = -oo )  <->  ( 0  < 
A  /\  B  = -oo ) ) )
2516, 14anbi12d 747 . . . . . . 7  |-  ( ( x  =  A  /\  y  =  B )  ->  ( ( x  <  0  /\  y  = +oo )  <->  ( A  <  0  /\  B  = +oo ) ) )
2624, 25orbi12d 746 . . . . . 6  |-  ( ( x  =  A  /\  y  =  B )  ->  ( ( ( 0  <  x  /\  y  = -oo )  \/  (
x  <  0  /\  y  = +oo )
)  <->  ( ( 0  <  A  /\  B  = -oo )  \/  ( A  <  0  /\  B  = +oo ) ) ) )
2723, 26orbi12d 746 . . . . 5  |-  ( ( x  =  A  /\  y  =  B )  ->  ( ( ( ( 0  <  y  /\  x  = -oo )  \/  ( y  <  0  /\  x  = +oo ) )  \/  (
( 0  <  x  /\  y  = -oo )  \/  ( x  <  0  /\  y  = +oo ) ) )  <-> 
( ( ( 0  <  B  /\  A  = -oo )  \/  ( B  <  0  /\  A  = +oo ) )  \/  ( ( 0  < 
A  /\  B  = -oo )  \/  ( A  <  0  /\  B  = +oo ) ) ) ) )
28 oveq12 6659 . . . . 5  |-  ( ( x  =  A  /\  y  =  B )  ->  ( x  x.  y
)  =  ( A  x.  B ) )
2927, 28ifbieq2d 4111 . . . 4  |-  ( ( x  =  A  /\  y  =  B )  ->  if ( ( ( ( 0  <  y  /\  x  = -oo )  \/  ( y  <  0  /\  x  = +oo ) )  \/  ( ( 0  < 
x  /\  y  = -oo )  \/  (
x  <  0  /\  y  = +oo )
) ) , -oo ,  ( x  x.  y ) )  =  if ( ( ( ( 0  <  B  /\  A  = -oo )  \/  ( B  <  0  /\  A  = +oo ) )  \/  ( ( 0  < 
A  /\  B  = -oo )  \/  ( A  <  0  /\  B  = +oo ) ) ) , -oo ,  ( A  x.  B ) ) )
3020, 29ifbieq2d 4111 . . 3  |-  ( ( x  =  A  /\  y  =  B )  ->  if ( ( ( ( 0  <  y  /\  x  = +oo )  \/  ( y  <  0  /\  x  = -oo ) )  \/  ( ( 0  < 
x  /\  y  = +oo )  \/  (
x  <  0  /\  y  = -oo )
) ) , +oo ,  if ( ( ( ( 0  <  y  /\  x  = -oo )  \/  ( y  <  0  /\  x  = +oo ) )  \/  ( ( 0  < 
x  /\  y  = -oo )  \/  (
x  <  0  /\  y  = +oo )
) ) , -oo ,  ( x  x.  y ) ) )  =  if ( ( ( ( 0  < 
B  /\  A  = +oo )  \/  ( B  <  0  /\  A  = -oo ) )  \/  ( ( 0  < 
A  /\  B  = +oo )  \/  ( A  <  0  /\  B  = -oo ) ) ) , +oo ,  if ( ( ( ( 0  <  B  /\  A  = -oo )  \/  ( B  <  0  /\  A  = +oo ) )  \/  (
( 0  <  A  /\  B  = -oo )  \/  ( A  <  0  /\  B  = +oo ) ) ) , -oo ,  ( A  x.  B ) ) ) )
315, 30ifbieq2d 4111 . 2  |-  ( ( x  =  A  /\  y  =  B )  ->  if ( ( x  =  0  \/  y  =  0 ) ,  0 ,  if ( ( ( ( 0  <  y  /\  x  = +oo )  \/  (
y  <  0  /\  x  = -oo )
)  \/  ( ( 0  <  x  /\  y  = +oo )  \/  ( x  <  0  /\  y  = -oo ) ) ) , +oo ,  if ( ( ( ( 0  <  y  /\  x  = -oo )  \/  (
y  <  0  /\  x  = +oo )
)  \/  ( ( 0  <  x  /\  y  = -oo )  \/  ( x  <  0  /\  y  = +oo ) ) ) , -oo ,  ( x  x.  y ) ) ) )  =  if ( ( A  =  0  \/  B  =  0 ) ,  0 ,  if ( ( ( ( 0  < 
B  /\  A  = +oo )  \/  ( B  <  0  /\  A  = -oo ) )  \/  ( ( 0  < 
A  /\  B  = +oo )  \/  ( A  <  0  /\  B  = -oo ) ) ) , +oo ,  if ( ( ( ( 0  <  B  /\  A  = -oo )  \/  ( B  <  0  /\  A  = +oo ) )  \/  (
( 0  <  A  /\  B  = -oo )  \/  ( A  <  0  /\  B  = +oo ) ) ) , -oo ,  ( A  x.  B ) ) ) ) )
32 df-xmul 11948 . 2  |-  xe  =  ( x  e. 
RR* ,  y  e.  RR*  |->  if ( ( x  =  0  \/  y  =  0 ) ,  0 ,  if ( ( ( ( 0  <  y  /\  x  = +oo )  \/  (
y  <  0  /\  x  = -oo )
)  \/  ( ( 0  <  x  /\  y  = +oo )  \/  ( x  <  0  /\  y  = -oo ) ) ) , +oo ,  if ( ( ( ( 0  <  y  /\  x  = -oo )  \/  (
y  <  0  /\  x  = +oo )
)  \/  ( ( 0  <  x  /\  y  = -oo )  \/  ( x  <  0  /\  y  = +oo ) ) ) , -oo ,  ( x  x.  y ) ) ) ) )
33 c0ex 10034 . . 3  |-  0  e.  _V
34 pnfex 10093 . . . 4  |- +oo  e.  _V
35 mnfxr 10096 . . . . . 6  |- -oo  e.  RR*
3635elexi 3213 . . . . 5  |- -oo  e.  _V
37 ovex 6678 . . . . 5  |-  ( A  x.  B )  e. 
_V
3836, 37ifex 4156 . . . 4  |-  if ( ( ( ( 0  <  B  /\  A  = -oo )  \/  ( B  <  0  /\  A  = +oo ) )  \/  ( ( 0  < 
A  /\  B  = -oo )  \/  ( A  <  0  /\  B  = +oo ) ) ) , -oo ,  ( A  x.  B ) )  e.  _V
3934, 38ifex 4156 . . 3  |-  if ( ( ( ( 0  <  B  /\  A  = +oo )  \/  ( B  <  0  /\  A  = -oo ) )  \/  ( ( 0  < 
A  /\  B  = +oo )  \/  ( A  <  0  /\  B  = -oo ) ) ) , +oo ,  if ( ( ( ( 0  <  B  /\  A  = -oo )  \/  ( B  <  0  /\  A  = +oo ) )  \/  (
( 0  <  A  /\  B  = -oo )  \/  ( A  <  0  /\  B  = +oo ) ) ) , -oo ,  ( A  x.  B ) ) )  e.  _V
4033, 39ifex 4156 . 2  |-  if ( ( A  =  0  \/  B  =  0 ) ,  0 ,  if ( ( ( ( 0  <  B  /\  A  = +oo )  \/  ( B  <  0  /\  A  = -oo ) )  \/  ( ( 0  < 
A  /\  B  = +oo )  \/  ( A  <  0  /\  B  = -oo ) ) ) , +oo ,  if ( ( ( ( 0  <  B  /\  A  = -oo )  \/  ( B  <  0  /\  A  = +oo ) )  \/  (
( 0  <  A  /\  B  = -oo )  \/  ( A  <  0  /\  B  = +oo ) ) ) , -oo ,  ( A  x.  B ) ) ) )  e. 
_V
4131, 32, 40ovmpt2a 6791 1  |-  ( ( A  e.  RR*  /\  B  e.  RR* )  ->  ( A xe B )  =  if ( ( A  =  0  \/  B  =  0 ) ,  0 ,  if ( ( ( ( 0  <  B  /\  A  = +oo )  \/  ( B  <  0  /\  A  = -oo ) )  \/  (
( 0  <  A  /\  B  = +oo )  \/  ( A  <  0  /\  B  = -oo ) ) ) , +oo ,  if ( ( ( ( 0  <  B  /\  A  = -oo )  \/  ( B  <  0  /\  A  = +oo ) )  \/  (
( 0  <  A  /\  B  = -oo )  \/  ( A  <  0  /\  B  = +oo ) ) ) , -oo ,  ( A  x.  B ) ) ) ) )
Colors of variables: wff setvar class
Syntax hints:    -> wi 4    \/ wo 383    /\ wa 384    = wceq 1483    e. wcel 1990   ifcif 4086   class class class wbr 4653  (class class class)co 6650   0cc0 9936    x. cmul 9941   +oocpnf 10071   -oocmnf 10072   RR*cxr 10073    < clt 10074   xecxmu 11945
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1722  ax-4 1737  ax-5 1839  ax-6 1888  ax-7 1935  ax-8 1992  ax-9 1999  ax-10 2019  ax-11 2034  ax-12 2047  ax-13 2246  ax-ext 2602  ax-sep 4781  ax-nul 4789  ax-pow 4843  ax-pr 4906  ax-un 6949  ax-cnex 9992  ax-1cn 9994  ax-icn 9995  ax-addcl 9996  ax-mulcl 9998  ax-i2m1 10004
This theorem depends on definitions:  df-bi 197  df-or 385  df-an 386  df-3an 1039  df-tru 1486  df-ex 1705  df-nf 1710  df-sb 1881  df-eu 2474  df-mo 2475  df-clab 2609  df-cleq 2615  df-clel 2618  df-nfc 2753  df-ral 2917  df-rex 2918  df-rab 2921  df-v 3202  df-sbc 3436  df-dif 3577  df-un 3579  df-in 3581  df-ss 3588  df-nul 3916  df-if 4087  df-pw 4160  df-sn 4178  df-pr 4180  df-op 4184  df-uni 4437  df-br 4654  df-opab 4713  df-id 5024  df-xp 5120  df-rel 5121  df-cnv 5122  df-co 5123  df-dm 5124  df-iota 5851  df-fun 5890  df-fv 5896  df-ov 6653  df-oprab 6654  df-mpt2 6655  df-pnf 10076  df-mnf 10077  df-xr 10078  df-xmul 11948
This theorem is referenced by:  xmulcom  12096  xmul01  12097  xmulneg1  12099  rexmul  12101  xmulpnf1  12104
  Copyright terms: Public domain W3C validator