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Theorem pssnel 4011
Description: A proper subclass has a member in one argument that's not in both. (Contributed by NM, 29-Feb-1996.)
Assertion
Ref Expression
pssnel (𝐴𝐵 → ∃𝑥(𝑥𝐵 ∧ ¬ 𝑥𝐴))
Distinct variable groups:   𝑥,𝐴   𝑥,𝐵

Proof of Theorem pssnel
StepHypRef Expression
1 pssdif 3919 . . 3 (𝐴𝐵 → (𝐵𝐴) ≠ ∅)
2 n0 3907 . . 3 ((𝐵𝐴) ≠ ∅ ↔ ∃𝑥 𝑥 ∈ (𝐵𝐴))
31, 2sylib 208 . 2 (𝐴𝐵 → ∃𝑥 𝑥 ∈ (𝐵𝐴))
4 eldif 3565 . . 3 (𝑥 ∈ (𝐵𝐴) ↔ (𝑥𝐵 ∧ ¬ 𝑥𝐴))
54exbii 1771 . 2 (∃𝑥 𝑥 ∈ (𝐵𝐴) ↔ ∃𝑥(𝑥𝐵 ∧ ¬ 𝑥𝐴))
63, 5sylib 208 1 (𝐴𝐵 → ∃𝑥(𝑥𝐵 ∧ ¬ 𝑥𝐴))
Colors of variables: wff setvar class
Syntax hints:  ¬ wn 3  wi 4  wa 384  wex 1701  wcel 1987  wne 2790  cdif 3552  wpss 3556  c0 3891
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1719  ax-4 1734  ax-5 1836  ax-6 1885  ax-7 1932  ax-9 1996  ax-10 2016  ax-11 2031  ax-12 2044  ax-13 2245  ax-ext 2601
This theorem depends on definitions:  df-bi 197  df-or 385  df-an 386  df-tru 1483  df-ex 1702  df-nf 1707  df-sb 1878  df-clab 2608  df-cleq 2614  df-clel 2617  df-nfc 2750  df-ne 2791  df-v 3188  df-dif 3558  df-in 3562  df-ss 3569  df-pss 3571  df-nul 3892
This theorem is referenced by:  php  8088  php3  8090  pssnn  8122  inf3lem2  8470  infpssr  9074  ssfin4  9076  genpnnp  9771  ltexprlem1  9802  reclem2pr  9814  mrieqv2d  16220  lbspss  19001  lsmcv  19060  lidlnz  19147  obslbs  19993  nmoid  22456  spansncvi  28357  lsat0cv  33797  osumcllem11N  34729  pexmidlem8N  34740  isomenndlem  40048
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