Goal:
  
  ============================
   (false <> true)


DEBUG:Going to execute:
reflexivity
Level 1: Backtrace:

 The relation (fun x y : bool => x <> y) is not a declared reflexive relation. Maybe you need to require the Coq.Classes.RelationClasses library
Level 0: Backtrace:

 The relation (fun x y : bool => x <> y) is not a declared reflexive relation. Maybe you need to require the Coq.Classes.RelationClasses library