(CONDITIONTYPE ORIENTED)
(VAR x)
(RULES
 even(0) -> true
 even(s(x)) -> true | odd(x) == true
 even(s(x)) -> false | even(x) == true
 odd(0) -> false
 odd(s(x)) -> true | even(x) == true
 odd(s(x)) -> false | odd(x) == true
)
(COMMENT
  doi: 10.4230/LIPIcs.RTA.2015.223 
  example 2
)