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 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 2 in a neighborhood of an imbedded circle representing an element of the homology group. The Arf invariant of this quadratic form is the Arf invariant of the knot. Let formula_1 be a Seifert matrix of