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Theorem abf 4401
Description: A class abstraction determined by a false formula is empty. (Contributed by NM, 20-Jan-2012.) Avoid ax-8 2108, ax-10 2137, ax-11 2154, ax-12 2171. (Revised by Gino Giotto, 30-Jun-2024.)
Hypothesis
Ref Expression
abf.1 ¬ 𝜑
Assertion
Ref Expression
abf {𝑥𝜑} = ∅

Proof of Theorem abf
StepHypRef Expression
1 abf.1 . . . 4 ¬ 𝜑
21bifal 1557 . . 3 (𝜑 ↔ ⊥)
32abbii 2802 . 2 {𝑥𝜑} = {𝑥 ∣ ⊥}
4 dfnul4 4323 . 2 ∅ = {𝑥 ∣ ⊥}
53, 4eqtr4i 2763 1 {𝑥𝜑} = ∅
Colors of variables: wff setvar class
Syntax hints:  ¬ wn 3   = wceq 1541  wfal 1553  {cab 2709  c0 4321
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1797  ax-4 1811  ax-5 1913  ax-6 1971  ax-7 2011  ax-9 2116  ax-ext 2703
This theorem depends on definitions:  df-bi 206  df-an 397  df-tru 1544  df-fal 1554  df-ex 1782  df-sb 2068  df-clab 2710  df-cleq 2724  df-dif 3950  df-nul 4322
This theorem is referenced by:  csbprc  4405  mpo0  7490  fi0  9411  join0  18354  meet0  18355  addsrid  27437  muls01  27557  mulsrid  27558  fmla0disjsuc  34377  0qs  37227  pmapglb2xN  38631
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