Theorem necon2ad 2421

Description: Contrapositive inference for inequality. (Contributed by NM, 19-Apr-2007.) (Proof rewritten by Jim Kingdon, 16-May-2018.)

Hypothesis

Ref	Expression
necon2ad.1	⊢ (𝜑 → (𝐴 = 𝐵 → ¬ 𝜓))

Assertion

Ref	Expression
necon2ad	⊢ (𝜑 → (𝜓 → 𝐴 ≠ 𝐵))

Proof of Theorem necon2ad

Step	Hyp	Ref	Expression
1		necon2ad.1	. . 3 ⊢ (𝜑 → (𝐴 = 𝐵 → ¬ 𝜓))
2	1	con2d 625	. 2 ⊢ (𝜑 → (𝜓 → ¬ 𝐴 = 𝐵))
3		df-ne 2365	. 2 ⊢ (𝐴 ≠ 𝐵 ↔ ¬ 𝐴 = 𝐵)
4	2, 3	imbitrrdi 162	1 ⊢ (𝜑 → (𝜓 → 𝐴 ≠ 𝐵))

Syntax hints:  ¬ wn 3   → wi 4   = wceq 1364   ≠ wne 2364

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-in1 615  ax-in2 616

This theorem depends on definitions:  df-bi 117  df-ne 2365

This theorem is referenced by:  necon2d  2423  prneimg  3800  tz7.2  4385  nordeq  4576  pr2ne  7252  ltne  8104  apne  8642  xrltne  9879  npnflt  9881  nmnfgt  9884  ge0nemnf  9890  rpexp  12291  sqrt2irr  12300  pcgcd1  12466  nzrunit  13684  lgsmod  15142