(VAR x f xs)
(RULES
  app(half, 0) -> 0
  app(half, app(s, 0)) -> 0
  app(half, app(s, app(s, x))) -> app(s, app(half, x))
  app(bits, 0) -> 0
  app(bits, app(s, x)) -> app(s, app(bits, app(half, app(s, x))))

  app(app(map,f),nil) -> nil
  app(app(map,f),app(app(cons,x),xs)) -> app(app(cons,app(f,x)),app(app(map,f),xs))

  app(app(filter,f),nil) -> nil
  app(app(filter,f),app(app(cons,x),xs)) -> app(app(app(app(filter2,app(f, x)),f),x),xs)
  app(app(app(app(filter2,true),f),x),xs) -> app(app(cons,x),app(app(filter,f),xs))
  app(app(app(app(filter2,false),f),x),xs) -> app(app(filter,f),xs)

)
(STRATEGY INNERMOST)