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Theorem nan 514
Description: Theorem to move a conjunct in and out of a negation.
Assertion
Ref Expression
nan ((φ → ¬ (ψχ)) ↔ ((φψ) → ¬ χ))

Proof of Theorem nan
StepHypRef Expression
1 impexp 276 . 2 (((φψ) → ¬ χ) ↔ (φ → (ψ → ¬ χ)))
2 imnan 207 . . 3 ((ψ → ¬ χ) ↔ ¬ (ψχ))
32imbi2i 160 . 2 ((φ → (ψ → ¬ χ)) ↔ (φ → ¬ (ψχ)))
41, 3bitr2 152 1 ((φ → ¬ (ψχ)) ↔ ((φψ) → ¬ χ))
Colors of variables: wff set class
Syntax hints:  ¬ wn 1   → wi 2   ↔ wb 127   ∧ wa 196
This theorem is referenced by:  cfsuc 3709
This theorem was proved from axioms:  ax-1 3  ax-2 4  ax-3 5  ax-mp 6
This theorem depends on definitions:  df-bi 128  df-an 198
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