Cowboy bowline so easily pushed back by accident. However, there is no documentation to confirm this claim, and some Dutch knot tyers outright deny it. Another piece of unverified lore is that it is called a winter bowline because the exposed working end on the outside would blow in the wind and prevent it from freezing to the loop on ships in the north Atlantic during winter. (This suggests that the standard bowline would be the summer bowline.) "The Ashley Book of Knots" states that it is "distinctly inferior" to the standard bowline because of its similarity to the left-hand sheet bend.
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