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Theorem nbior 923
Description: If two propositions are not equivalent, then at least one is true. (Contributed by BJ, 19-Apr-2019.) (Proof shortened by Wolf Lammen, 19-Jan-2020.)
Assertion
Ref Expression
nbior (¬ (𝜑𝜓) → (𝜑𝜓))

Proof of Theorem nbior
StepHypRef Expression
1 norbi 922 . 2 (¬ (𝜑𝜓) → (𝜑𝜓))
21con1i 144 1 (¬ (𝜑𝜓) → (𝜑𝜓))
Colors of variables: wff setvar class
Syntax hints:  ¬ wn 3  wi 4  wb 196  wo 382
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8
This theorem depends on definitions:  df-bi 197  df-or 384
This theorem is referenced by:  nmogtmnf  27753  nmopgtmnf  28855
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