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Theorem nannot 1529
Description: Negation in terms of alternative denial. (Contributed by Jeff Hoffman, 19-Nov-2007.) Use dfnan2 1524. (Revised by Wolf Lammen, 26-Jun-2020.)
Assertion
Ref Expression
nannot 𝜑 ↔ (𝜑𝜑))

Proof of Theorem nannot
StepHypRef Expression
1 dfnan2 1524 . 2 ((𝜑𝜑) ↔ (𝜑 → ¬ 𝜑))
2 pm4.8 398 . 2 ((𝜑 → ¬ 𝜑) ↔ ¬ 𝜑)
31, 2bitr2i 279 1 𝜑 ↔ (𝜑𝜑))
Colors of variables:    wff setvar class
This proof depends on syntax axioms:  ¬ wn 3  wi 4  wb 209  wnan 1521
This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8
This proof depends on definitions:  df-bi 210  df-an 402  df-nan 1522
This theorem is used by:  nanbi  1530  trunantru  1611  falnanfal  1614  nic-dfneg  1703  andnand1  36953  imnand2  36954
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