ILE Home Intuitionistic Logic Explorer < Previous   Next >
Nearby theorems
Mirrors  >  Home  >  ILE Home  >  Th. List  >  necon2bbii Unicode version

Theorem necon2bbii 2320
Description: Contrapositive inference for inequality. (Contributed by Jim Kingdon, 16-May-2018.)
Hypothesis
Ref Expression
necon2bbii.1  |-  (DECID  A  =  B  ->  ( ph  <->  A  =/=  B ) )
Assertion
Ref Expression
necon2bbii  |-  (DECID  A  =  B  ->  ( A  =  B  <->  -.  ph ) )

Proof of Theorem necon2bbii
StepHypRef Expression
1 necon2bbii.1 . . . 4  |-  (DECID  A  =  B  ->  ( ph  <->  A  =/=  B ) )
21bicomd 139 . . 3  |-  (DECID  A  =  B  ->  ( A  =/=  B  <->  ph ) )
32necon1bbiidc 2316 . 2  |-  (DECID  A  =  B  ->  ( -.  ph  <->  A  =  B ) )
43bicomd 139 1  |-  (DECID  A  =  B  ->  ( A  =  B  <->  -.  ph ) )
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: (None)
  Copyright terms: Public domain W3C validator