MAYBE MAYBE TRS: { minus(x, 0()) -> x, minus(minus(x, y), z) -> minus(x, plus(y, z)), minus(0(), y) -> 0(), minus(s(x), s(y)) -> minus(x, y), plus(0(), y) -> y, plus(s(x), y) -> plus(x, s(y)), plus(s(x), y) -> s(plus(y, x)), zero(0()) -> true(), zero(s(x)) -> false(), p(0()) -> 0(), p(s(x)) -> x, quot(0(), s(y), z) -> z, quot(s(x), s(y), z) -> quot(minus(p(ack(0(), x)), y), s(y), s(z)), div(x, y) -> quot(x, y, 0()), ack(0(), x) -> plus(x, s(0())), ack(0(), x) -> s(x), ack(s(x), 0()) -> ack(x, s(0())), ack(s(x), s(y)) -> ack(x, ack(s(x), y)) } DUP: We consider a duplicating system. Trs: { minus(x, 0()) -> x, minus(minus(x, y), z) -> minus(x, plus(y, z)), minus(0(), y) -> 0(), minus(s(x), s(y)) -> minus(x, y), plus(0(), y) -> y, plus(s(x), y) -> plus(x, s(y)), plus(s(x), y) -> s(plus(y, x)), zero(0()) -> true(), zero(s(x)) -> false(), p(0()) -> 0(), p(s(x)) -> x, quot(0(), s(y), z) -> z, quot(s(x), s(y), z) -> quot(minus(p(ack(0(), x)), y), s(y), s(z)), div(x, y) -> quot(x, y, 0()), ack(0(), x) -> plus(x, s(0())), ack(0(), x) -> s(x), ack(s(x), 0()) -> ack(x, s(0())), ack(s(x), s(y)) -> ack(x, ack(s(x), y)) } Fail