(CONDITIONTYPE ORIENTED)
(VAR x)
(RULES
  e(0) -> true
  e(s(x)) -> true  | e(x) == false
  e(s(x)) -> false | e(x) == true
)
(COMMENT
  [Nishida, Yanagisawa, and Gmeiner, IWC 2014, Example 2]
)