Theorem necon2bi 2458

Description: Contrapositive inference for inequality. (Contributed by NM, 1-Apr-2007.)

Hypothesis

Ref	Expression
necon2bi.1	⊢ (𝜑 → 𝐴 ≠ 𝐵)

Assertion

Ref	Expression
necon2bi	⊢ (𝐴 = 𝐵 → ¬ 𝜑)

Proof of Theorem necon2bi

Step	Hyp	Ref	Expression
1		necon2bi.1	. . 3 ⊢ (𝜑 → 𝐴 ≠ 𝐵)
2	1	neneqd 2424	. 2 ⊢ (𝜑 → ¬ 𝐴 = 𝐵)
3	2	con2i 632	1 ⊢ (𝐴 = 𝐵 → ¬ 𝜑)

Syntax hints:  ¬ wn 3   → wi 4   = wceq 1398   ≠ wne 2403

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-in1 619  ax-in2 620

This theorem depends on definitions:  df-bi 117  df-ne 2404

This theorem is referenced by:  minel  3558  rzal  3594  difsnb  3821  fin0  7117  0npi  7576  0nsr  8012  renfdisj  8282  nltpnft  10092  ngtmnft  10095  xrrebnd  10097  hashnncl  11101  rennim  11623  pceq0  12956