Double bowline with a bight of rope instead of the end. First, learn to tie the bowline by laying the working end on the standing part and twisting to form a loop (the "hole" that the rabbit comes out of). Wrap the loop once more around the working end. Then pass the working end behind the standing part and back down through the double loop. The double bowline is one of the typical tie-in knots used in climbing, along with the figure eight follow through and the Yosemite bowline. The advantage of the double bowline over the figure 8 is that it
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