“…It is also clear that if a prime alternating presentation P (Γ, R) of a knot contains at least one crossing, then the knot is not trivial, as it is easy to show that the shortest relation has length 4, and all the generators of P (Γ, R) are meridians or their inverses (see [5]). If the group were Z, then there would be a relation of length 2.…”