src/HOL/ex/svc_test.thy

Now that 0 is overloaded, constant "zero" and its type class "zero" are
no longer needed. Also IntRingDefs is redundant

svc_test = Main +

syntax
    "<->"         :: [bool, bool] => bool                  (infixr 25)

translations
  "x <-> y" => "x = y"

end