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Theorem necon1bbiddc 2318
 Description: Contrapositive inference for inequality. (Contributed by Jim Kingdon, 16-May-2018.)
Hypothesis
Ref Expression
necon1bbiddc.1 (𝜑 → (DECID 𝐴 = 𝐵 → (𝐴𝐵𝜓)))
Assertion
Ref Expression
necon1bbiddc (𝜑 → (DECID 𝐴 = 𝐵 → (¬ 𝜓𝐴 = 𝐵)))

Proof of Theorem necon1bbiddc
StepHypRef Expression
1 necon1bbiddc.1 . . 3 (𝜑 → (DECID 𝐴 = 𝐵 → (𝐴𝐵𝜓)))
2 df-ne 2256 . . . 4 (𝐴𝐵 ↔ ¬ 𝐴 = 𝐵)
32bibi1i 226 . . 3 ((𝐴𝐵𝜓) ↔ (¬ 𝐴 = 𝐵𝜓))
41, 3syl6ib 159 . 2 (𝜑 → (DECID 𝐴 = 𝐵 → (¬ 𝐴 = 𝐵𝜓)))
54con1biddc 808 1 (𝜑 → (DECID 𝐴 = 𝐵 → (¬ 𝜓𝐴 = 𝐵)))
 Colors of variables: wff set class Syntax hints:  ¬ wn 3   → wi 4   ↔ wb 103  DECID wdc 780   = wceq 1289   ≠ wne 2255 This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 104  ax-ia2 105  ax-ia3 106  ax-in1 579  ax-in2 580  ax-io 665 This theorem depends on definitions:  df-bi 115  df-dc 781  df-ne 2256 This theorem is referenced by:  necon2bbiddc  2322
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