Theorem necon2bbii 2833

Description: Contrapositive inference for inequality. (Contributed by NM, 13-Apr-2007.)

Hypothesis

Ref	Expression
necon2bbii.1	⊢ (𝜑 ↔ 𝐴 ≠ 𝐵)

Assertion

Ref	Expression
necon2bbii	⊢ (𝐴 = 𝐵 ↔ ¬ 𝜑)

Proof of Theorem necon2bbii

Step	Hyp	Ref	Expression
1		necon2bbii.1	. . . 4 ⊢ (𝜑 ↔ 𝐴 ≠ 𝐵)
2	1	bicomi 213	. . 3 ⊢ (𝐴 ≠ 𝐵 ↔ 𝜑)
3	2	necon1bbii 2831	. 2 ⊢ (¬ 𝜑 ↔ 𝐴 = 𝐵)
4	3	bicomi 213	1 ⊢ (𝐴 = 𝐵 ↔ ¬ 𝜑)

Syntax hints:  ¬ wn 3   ↔ wb 195   = wceq 1475   ≠ wne 2780

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 196  df-ne 2782

This theorem is referenced by:  xpeq0  5473  dmsn0  5520  disjex  28787  disjexc  28788  suppss3  28890