Eskimo bowline structure of the knot was not identified by Clifford Ashley (in 1944). All of the maneuvers to tie this knot are generally in the opposite (or 'anti' direction) relative to the bowline. Dan Lehman regards the general, bowline-like structure as an 'anti-bowline' in the sense of "anti-clockwise": in that with regard to the main nipping loop, the tail on returning from forming the eye is brought through this loop in the opposite direction relative to what is done for a bowline. When this knot is ring-loaded – and the knot effectively becomes an end-to-end knot – it is effectively a
Arf invariant of a knot slice knot is a square integer. As formula_12 is an odd integer, it has to be congruent to 1 modulo 8. Combined with Murasugi's result this shows that the Arf invariant of a slice knot vanishes. Arf invariant of a knot In the mathematical field of knot theory, the Arf invariant of a knot, named after Cahit Arf, is a knot invariant obtained from a quadratic form associated to a Seifert surface. If "F" is a Seifert surface of a knot, then the homology group H("F", Z/2Z) has a quadratic form whose value is the number of full twists mod