(VAR x y) (RULES nats -> :(0,inc(nats)) inc(:(x,y)) -> :(s(x),inc(y)) inc(tl(nats)) -> tl(inc(nats)) hd(:(x,y)) -> x tl(:(x,y)) -> y d(:(x,y)) -> :(x,:(x,d(y))) ) (COMMENT Example 3 from [HM11]: doi: http://dx.doi.org/10.1007/s10817-011-9238-x )