Cowboy bowline Cowboy bowline The cowboy bowline (also left-hand bowline, Dutch marine bowline or winter bowline) is a variation of the bowline loop knot. The cowboy bowline has the working end go around the standing part on the side closer to the loop and results with the working end outside the loop. In contrast, a regular bowline has the working end finishing inside the loop. (The "rabbit" goes around the "tree" in the opposite direction from normal.) Some hearsay suggest the Dutch Navy uses (or used) this variant of the bowline because they consider it superior since the working end is not
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