Input TRS:
    1: rev(nil()) -> nil()
    2: rev(.(x,y)) -> ++(rev(y),.(x,nil()))
    3: car(.(x,y)) -> x
    4: cdr(.(x,y)) -> y
    5: null(nil()) -> true()
    6: null(.(x,y)) -> false()
    7: ++(nil(),y) -> y
    8: ++(.(x,y),z) -> .(x,++(y,z))
Number of Rules: 8
Direct POLO(mSum) ... failed.