K. Murasugi has conjectured
that if every pair of the μ components of a classical link L has linking number ±1,
then the group G of L will have the property that Gq∕Gq+1≅Fq∕Fq+1∀q ≥ 2, where
F is free on μ − 1 generators. (The conjecture has been verified by other authors.)
Here we show that this property is equivalent to the special case G2∕G3≅F2∕F3, and
also give other equivalent conditions.