ILE Home Intuitionistic Logic Explorer < Previous   Next >
Nearby theorems
Mirrors  >  Home  >  ILE Home  >  Th. List  >  necon4aidc GIF version

Theorem necon4aidc 2351
Description: Contrapositive inference for inequality. (Contributed by Jim Kingdon, 16-May-2018.)
Hypothesis
Ref Expression
necon4aidc.1 (DECID 𝐴 = 𝐵 → (𝐴𝐵 → ¬ 𝜑))
Assertion
Ref Expression
necon4aidc (DECID 𝐴 = 𝐵 → (𝜑𝐴 = 𝐵))

Proof of Theorem necon4aidc
StepHypRef Expression
1 df-ne 2284 . . 3 (𝐴𝐵 ↔ ¬ 𝐴 = 𝐵)
2 necon4aidc.1 . . 3 (DECID 𝐴 = 𝐵 → (𝐴𝐵 → ¬ 𝜑))
31, 2syl5bir 152 . 2 (DECID 𝐴 = 𝐵 → (¬ 𝐴 = 𝐵 → ¬ 𝜑))
4 condc 821 . 2 (DECID 𝐴 = 𝐵 → ((¬ 𝐴 = 𝐵 → ¬ 𝜑) → (𝜑𝐴 = 𝐵)))
53, 4mpd 13 1 (DECID 𝐴 = 𝐵 → (𝜑𝐴 = 𝐵))
Colors of variables: wff set class
Syntax hints:  ¬ wn 3  wi 4  DECID wdc 802   = wceq 1314  wne 2283
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-in1 586  ax-in2 587  ax-io 681
This theorem depends on definitions:  df-bi 116  df-stab 799  df-dc 803  df-ne 2284
This theorem is referenced by:  necon4idc  2352
  Copyright terms: Public domain W3C validator