MPE Home Metamath Proof Explorer < Previous   Next >
Nearby theorems
Mirrors  >  Home  >  MPE Home  >  Th. List  >  nabbi Structured version   Visualization version   GIF version

Theorem nabbi 2879
Description: Not equivalent wff's correspond to not equal class abstractions. (Contributed by AV, 7-Apr-2019.) (Proof shortened by Wolf Lammen, 25-Nov-2019.)
Assertion
Ref Expression
nabbi (∃𝑥(𝜑 ↔ ¬ 𝜓) ↔ {𝑥𝜑} ≠ {𝑥𝜓})

Proof of Theorem nabbi
StepHypRef Expression
1 df-ne 2777 . 2 ({𝑥𝜑} ≠ {𝑥𝜓} ↔ ¬ {𝑥𝜑} = {𝑥𝜓})
2 exnal 1742 . . . 4 (∃𝑥 ¬ (𝜑𝜓) ↔ ¬ ∀𝑥(𝜑𝜓))
3 xor3 370 . . . . 5 (¬ (𝜑𝜓) ↔ (𝜑 ↔ ¬ 𝜓))
43exbii 1762 . . . 4 (∃𝑥 ¬ (𝜑𝜓) ↔ ∃𝑥(𝜑 ↔ ¬ 𝜓))
52, 4bitr3i 264 . . 3 (¬ ∀𝑥(𝜑𝜓) ↔ ∃𝑥(𝜑 ↔ ¬ 𝜓))
6 abbi 2719 . . 3 (∀𝑥(𝜑𝜓) ↔ {𝑥𝜑} = {𝑥𝜓})
75, 6xchnxbi 320 . 2 (¬ {𝑥𝜑} = {𝑥𝜓} ↔ ∃𝑥(𝜑 ↔ ¬ 𝜓))
81, 7bitr2i 263 1 (∃𝑥(𝜑 ↔ ¬ 𝜓) ↔ {𝑥𝜑} ≠ {𝑥𝜓})
Colors of variables: wff setvar class
Syntax hints:  ¬ wn 3  wb 194  wal 1472   = wceq 1474  wex 1694  {cab 2591  wne 2775
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1711  ax-4 1726  ax-5 1825  ax-6 1873  ax-7 1920  ax-10 2004  ax-11 2019  ax-12 2031  ax-13 2228  ax-ext 2585
This theorem depends on definitions:  df-bi 195  df-or 383  df-an 384  df-tru 1477  df-ex 1695  df-nf 1700  df-sb 1866  df-clab 2592  df-cleq 2598  df-clel 2601  df-ne 2777
This theorem is referenced by:  suppvalbr  7159
  Copyright terms: Public domain W3C validator