Uni knot Uni knot The uni knot is a multi purpose fishing knot that can be used for attaching the fishing line to the arbor of a reel, for joining lines, and for attaching lures, snaps, and swivels. The knot, shown with three passes, was published in 1944 under the name gallows knot (#1121) in The Ashley Book of Knots. Ashley notes that it is actually an alternate arrangement of the multiple overhand noose. His diagram shows how the knot can be manipulated into the more familiar form. This knot is also called the Duncan loop, after Norman Duncan who developed 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