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Theorem difid 3313
Description: The difference between a class and itself is the empty set. Proposition 5.15 of [TakeutiZaring] p. 20. Also Theorem 32 of [Suppes] p. 28. (Contributed by NM, 22-Apr-2004.)
Assertion
Ref Expression
difid  |-  ( A 
\  A )  =  (/)

Proof of Theorem difid
StepHypRef Expression
1 ssid 3019 . 2  |-  A  C_  A
2 ssdif0im 3309 . 2  |-  ( A 
C_  A  ->  ( A  \  A )  =  (/) )
31, 2ax-mp 7 1  |-  ( A 
\  A )  =  (/)
Colors of variables: wff set class
Syntax hints:    = wceq 1285    \ cdif 2971    C_ wss 2974   (/)c0 3252
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 104  ax-ia2 105  ax-ia3 106  ax-in1 577  ax-in2 578  ax-io 663  ax-5 1377  ax-7 1378  ax-gen 1379  ax-ie1 1423  ax-ie2 1424  ax-8 1436  ax-10 1437  ax-11 1438  ax-i12 1439  ax-bndl 1440  ax-4 1441  ax-17 1460  ax-i9 1464  ax-ial 1468  ax-i5r 1469  ax-ext 2064
This theorem depends on definitions:  df-bi 115  df-tru 1288  df-nf 1391  df-sb 1687  df-clab 2069  df-cleq 2075  df-clel 2078  df-nfc 2209  df-v 2604  df-dif 2976  df-in 2980  df-ss 2987  df-nul 3253
This theorem is referenced by:  dif0  3315  difun2  3323  diftpsn3  3529  2oconcl  6080
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