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Theorem ninba 927
Description: Miscellaneous inference relating falsehoods. (Contributed by NM, 31-Mar-1994.)
Hypothesis
Ref Expression
ninba.1 φ
Assertion
Ref Expression
ninba ψ → (¬ φ ↔ (χ ψ)))

Proof of Theorem ninba
StepHypRef Expression
1 ninba.1 . . 3 φ
21niabn 917 . 2 ψ → ((χ ψ) ↔ ¬ φ))
32bicomd 192 1 ψ → (¬ φ ↔ (χ ψ)))
Colors of variables: wff setvar class
Syntax hints:  ¬ wn 3  wi 4  wb 176   wa 358
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 177  df-an 360
This theorem is referenced by: (None)
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