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Theorem eldifpr 23409
Description: Membership in a set with two elements removed. Similar to eldifsn 3762 and eldiftp 23410. (Contributed by Mario Carneiro, 18-Jul-2017.)
Assertion
Ref Expression
eldifpr  |-  ( A  e.  ( B  \  { C ,  D }
)  <->  ( A  e.  B  /\  A  =/= 
C  /\  A  =/=  D ) )

Proof of Theorem eldifpr
StepHypRef Expression
1 elprg 3670 . . . . 5  |-  ( A  e.  B  ->  ( A  e.  { C ,  D }  <->  ( A  =  C  \/  A  =  D ) ) )
21notbid 285 . . . 4  |-  ( A  e.  B  ->  ( -.  A  e.  { C ,  D }  <->  -.  ( A  =  C  \/  A  =  D )
) )
3 neanior 2544 . . . 4  |-  ( ( A  =/=  C  /\  A  =/=  D )  <->  -.  ( A  =  C  \/  A  =  D )
)
42, 3syl6bbr 254 . . 3  |-  ( A  e.  B  ->  ( -.  A  e.  { C ,  D }  <->  ( A  =/=  C  /\  A  =/= 
D ) ) )
54pm5.32i 618 . 2  |-  ( ( A  e.  B  /\  -.  A  e.  { C ,  D } )  <->  ( A  e.  B  /\  ( A  =/=  C  /\  A  =/=  D ) ) )
6 eldif 3175 . 2  |-  ( A  e.  ( B  \  { C ,  D }
)  <->  ( A  e.  B  /\  -.  A  e.  { C ,  D } ) )
7 3anass 938 . 2  |-  ( ( A  e.  B  /\  A  =/=  C  /\  A  =/=  D )  <->  ( A  e.  B  /\  ( A  =/=  C  /\  A  =/=  D ) ) )
85, 6, 73bitr4i 268 1  |-  ( A  e.  ( B  \  { C ,  D }
)  <->  ( A  e.  B  /\  A  =/= 
C  /\  A  =/=  D ) )
Colors of variables: wff set class
Syntax hints:   -. wn 3    <-> wb 176    \/ wo 357    /\ wa 358    /\ w3a 934    = wceq 1632    e. wcel 1696    =/= wne 2459    \ cdif 3162   {cpr 3654
This theorem is referenced by:  logbcl  23414  logbid1  23415  rnlogbval  23417  relogbcl  23419  logb1  23420  nnlogbexp  23421  elogb  28513
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-3 7  ax-mp 8  ax-gen 1536  ax-5 1547  ax-17 1606  ax-9 1644  ax-8 1661  ax-6 1715  ax-7 1720  ax-11 1727  ax-12 1878  ax-ext 2277
This theorem depends on definitions:  df-bi 177  df-or 359  df-an 360  df-3an 936  df-tru 1310  df-ex 1532  df-nf 1535  df-sb 1639  df-clab 2283  df-cleq 2289  df-clel 2292  df-nfc 2421  df-ne 2461  df-v 2803  df-dif 3168  df-un 3170  df-sn 3659  df-pr 3660
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