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Theorem en3lplem1 7596
Description: Lemma for en3lp 7598. (Contributed by Alan Sare, 28-Oct-2011.)
Assertion
Ref Expression
en3lplem1  |-  ( ( A  e.  B  /\  B  e.  C  /\  C  e.  A )  ->  ( x  =  A  ->  ( x  i^i 
{ A ,  B ,  C } )  =/=  (/) ) )
Distinct variable groups:    x, A    x, B    x, C

Proof of Theorem en3lplem1
StepHypRef Expression
1 simp3 959 . . 3  |-  ( ( A  e.  B  /\  B  e.  C  /\  C  e.  A )  ->  C  e.  A )
2 eleq2 2441 . . 3  |-  ( x  =  A  ->  ( C  e.  x  <->  C  e.  A ) )
31, 2syl5ibrcom 214 . 2  |-  ( ( A  e.  B  /\  B  e.  C  /\  C  e.  A )  ->  ( x  =  A  ->  C  e.  x
) )
4 tpid3g 3855 . . . . 5  |-  ( C  e.  A  ->  C  e.  { A ,  B ,  C } )
543ad2ant3 980 . . . 4  |-  ( ( A  e.  B  /\  B  e.  C  /\  C  e.  A )  ->  C  e.  { A ,  B ,  C }
)
6 inelcm 3618 . . . 4  |-  ( ( C  e.  x  /\  C  e.  { A ,  B ,  C }
)  ->  ( x  i^i  { A ,  B ,  C } )  =/=  (/) )
75, 6sylan2 461 . . 3  |-  ( ( C  e.  x  /\  ( A  e.  B  /\  B  e.  C  /\  C  e.  A
) )  ->  (
x  i^i  { A ,  B ,  C }
)  =/=  (/) )
87expcom 425 . 2  |-  ( ( A  e.  B  /\  B  e.  C  /\  C  e.  A )  ->  ( C  e.  x  ->  ( x  i^i  { A ,  B ,  C } )  =/=  (/) ) )
93, 8syld 42 1  |-  ( ( A  e.  B  /\  B  e.  C  /\  C  e.  A )  ->  ( x  =  A  ->  ( x  i^i 
{ A ,  B ,  C } )  =/=  (/) ) )
Colors of variables: wff set class
Syntax hints:    -> wi 4    /\ w3a 936    = wceq 1649    e. wcel 1717    =/= wne 2543    i^i cin 3255   (/)c0 3564   {ctp 3752
This theorem is referenced by:  en3lplem2  7597
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-3 7  ax-mp 8  ax-gen 1552  ax-5 1563  ax-17 1623  ax-9 1661  ax-8 1682  ax-6 1736  ax-7 1741  ax-11 1753  ax-12 1939  ax-ext 2361
This theorem depends on definitions:  df-bi 178  df-or 360  df-an 361  df-3or 937  df-3an 938  df-tru 1325  df-ex 1548  df-nf 1551  df-sb 1656  df-clab 2367  df-cleq 2373  df-clel 2376  df-nfc 2505  df-ne 2545  df-v 2894  df-dif 3259  df-un 3261  df-in 3263  df-nul 3565  df-sn 3756  df-pr 3757  df-tp 3758
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