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Theorem coass 5097
Description: Associative law for class composition. Theorem 27 of [Suppes] p. 64. Also Exercise 21 of [Enderton] p. 53. Interestingly, this law holds for any classes whatsoever, not just functions or even relations. (Contributed by NM, 27-Jan-1997.)
Assertion
Ref Expression
coass  |-  ( ( A  o.  B )  o.  C )  =  ( A  o.  ( B  o.  C )
)

Proof of Theorem coass
StepHypRef Expression
1 relco 5077 . 2  |-  Rel  (
( A  o.  B
)  o.  C )
2 relco 5077 . 2  |-  Rel  ( A  o.  ( B  o.  C ) )
3 excom 1765 . . . 4  |-  ( E. z E. w ( x C z  /\  ( z B w  /\  w A y ) )  <->  E. w E. z ( x C z  /\  ( z B w  /\  w A y ) ) )
4 anass 633 . . . . 5  |-  ( ( ( x C z  /\  z B w )  /\  w A y )  <->  ( x C z  /\  (
z B w  /\  w A y ) ) )
542exbii 1581 . . . 4  |-  ( E. w E. z ( ( x C z  /\  z B w )  /\  w A y )  <->  E. w E. z ( x C z  /\  ( z B w  /\  w A y ) ) )
63, 5bitr4i 245 . . 3  |-  ( E. z E. w ( x C z  /\  ( z B w  /\  w A y ) )  <->  E. w E. z ( ( x C z  /\  z B w )  /\  w A y ) )
7 vex 2730 . . . . . . 7  |-  z  e. 
_V
8 vex 2730 . . . . . . 7  |-  y  e. 
_V
97, 8brco 4759 . . . . . 6  |-  ( z ( A  o.  B
) y  <->  E. w
( z B w  /\  w A y ) )
109anbi2i 678 . . . . 5  |-  ( ( x C z  /\  z ( A  o.  B ) y )  <-> 
( x C z  /\  E. w ( z B w  /\  w A y ) ) )
1110exbii 1580 . . . 4  |-  ( E. z ( x C z  /\  z ( A  o.  B ) y )  <->  E. z
( x C z  /\  E. w ( z B w  /\  w A y ) ) )
12 vex 2730 . . . . 5  |-  x  e. 
_V
1312, 8opelco 4760 . . . 4  |-  ( <.
x ,  y >.  e.  ( ( A  o.  B )  o.  C
)  <->  E. z ( x C z  /\  z
( A  o.  B
) y ) )
14 exdistr 2039 . . . 4  |-  ( E. z E. w ( x C z  /\  ( z B w  /\  w A y ) )  <->  E. z
( x C z  /\  E. w ( z B w  /\  w A y ) ) )
1511, 13, 143bitr4i 270 . . 3  |-  ( <.
x ,  y >.  e.  ( ( A  o.  B )  o.  C
)  <->  E. z E. w
( x C z  /\  ( z B w  /\  w A y ) ) )
16 vex 2730 . . . . . . 7  |-  w  e. 
_V
1712, 16brco 4759 . . . . . 6  |-  ( x ( B  o.  C
) w  <->  E. z
( x C z  /\  z B w ) )
1817anbi1i 679 . . . . 5  |-  ( ( x ( B  o.  C ) w  /\  w A y )  <->  ( E. z ( x C z  /\  z B w )  /\  w A y ) )
1918exbii 1580 . . . 4  |-  ( E. w ( x ( B  o.  C ) w  /\  w A y )  <->  E. w
( E. z ( x C z  /\  z B w )  /\  w A y ) )
2012, 8opelco 4760 . . . 4  |-  ( <.
x ,  y >.  e.  ( A  o.  ( B  o.  C )
)  <->  E. w ( x ( B  o.  C
) w  /\  w A y ) )
21 19.41v 2034 . . . . 5  |-  ( E. z ( ( x C z  /\  z B w )  /\  w A y )  <->  ( E. z ( x C z  /\  z B w )  /\  w A y ) )
2221exbii 1580 . . . 4  |-  ( E. w E. z ( ( x C z  /\  z B w )  /\  w A y )  <->  E. w
( E. z ( x C z  /\  z B w )  /\  w A y ) )
2319, 20, 223bitr4i 270 . . 3  |-  ( <.
x ,  y >.  e.  ( A  o.  ( B  o.  C )
)  <->  E. w E. z
( ( x C z  /\  z B w )  /\  w A y ) )
246, 15, 233bitr4i 270 . 2  |-  ( <.
x ,  y >.  e.  ( ( A  o.  B )  o.  C
)  <->  <. x ,  y
>.  e.  ( A  o.  ( B  o.  C
) ) )
251, 2, 24eqrelriiv 4688 1  |-  ( ( A  o.  B )  o.  C )  =  ( A  o.  ( B  o.  C )
)
Colors of variables: wff set class
Syntax hints:    /\ wa 360   E.wex 1537    = wceq 1619    e. wcel 1621   <.cop 3547   class class class wbr 3920    o. ccom 4584
This theorem is referenced by:  funcoeqres  5361  fcof1o  5655  tposco  6117  mapen  6910  mapfien  7283  hashfacen  11269  cofuass  13607  setccatid  13760  frmdup3  14323  symggrp  14615  gsumval3  15026  gsumzf1o  15031  gsumzmhm  15045  prds1  15232  psrass1lem  15955  qtophmeo  17340  uniioombllem2  18770  cncombf  18845  pf1mpf  19267  pf1ind  19270  pjsdi2i  22567  pjadj2coi  22614  pj3lem1  22616  pj3i  22618  derangenlem  22873  subfacp1lem5  22886  erdsze2lem2  22906  relexpsucl  23199  relexpadd  23206  pprodcnveq  23598  hmeogrpi  24702  cmpmorass  25132  cocnv  25559  diophrw  26004  eldioph2  26007  f1omvdco2  26557  symggen  26577  psgnunilem1  26582  mendrng  26666  ltrncoidN  29006  trlcoabs2N  29600  trlcoat  29601  trlcone  29606  cdlemg46  29613  cdlemg47  29614  ltrnco4  29617  tgrpgrplem  29627  tendoplass  29661  cdlemi2  29697  cdlemk2  29710  cdlemk4  29712  cdlemk8  29716  cdlemk45  29825  cdlemk54  29836  cdlemk55a  29837  erngdvlem3  29868  erngdvlem3-rN  29876  tendocnv  29900  dvhvaddass  29976  dvhlveclem  29987  cdlemn8  30083  dihopelvalcpre  30127  dih1dimatlem0  30207
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-14 1626  ax-17 1628  ax-12o 1664  ax-10 1678  ax-9 1684  ax-4 1692  ax-16 1926  ax-ext 2234  ax-sep 4038  ax-nul 4046  ax-pr 4108
This theorem depends on definitions:  df-bi 179  df-or 361  df-an 362  df-3an 941  df-tru 1315  df-ex 1538  df-nf 1540  df-sb 1883  df-eu 2118  df-mo 2119  df-clab 2240  df-cleq 2246  df-clel 2249  df-nfc 2374  df-ne 2414  df-ral 2513  df-rex 2514  df-rab 2516  df-v 2729  df-dif 3081  df-un 3083  df-in 3085  df-ss 3089  df-nul 3363  df-if 3471  df-sn 3550  df-pr 3551  df-op 3553  df-br 3921  df-opab 3975  df-xp 4594  df-rel 4595  df-co 4597
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