Theorem nbfal 1585

Description: The negation of a proposition is equivalent to itself being equivalent to ⊥. (Contributed by Anthony Hart, 14-Aug-2011.)

Assertion

Ref	Expression
nbfal	⊢ (¬ 𝜑 ↔ (𝜑 ↔ ⊥))

Proof of Theorem nbfal

Step	Hyp	Ref	Expression
1		fal 1584	. 2 ⊢ ¬ ⊥
2	1	nbn 375	1 ⊢ (¬ 𝜑 ↔ (𝜑 ↔ ⊥))

Syntax hints:  ¬ wn 3   ↔ wb 209  ⊥wfal 1582

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 210  df-tru 1573  df-fal 1583

This theorem is referenced by:  nulmo  2740  eq0  4304  ab0w  4335  ab0  4336  bisym1  36950  wl-1xor  38148  wl-1mintru1  38154  aisfina  47655  aifftbifffaibifff  47679  lindslinindsimp2  49263