Karash double loop harness. The traditional method of tying this knot starts with a reverse loop (like the Eskimo bowline) then wraps around the standing end (AKA the "tree"), you then finish the knot the same way as the BOAB – Bowline on a bight. An alternative way as advertised by the French Federation of Speleology and Mike Karash is starting with a figure of eight on a bight, then pulls two strands of the rope back through the bight. Karash double loop Karash double loop is a common name for a knot forming two loops. This knot has been a known variant
Arf invariant of a knot if they are related by a finite sequence of pass-moves, which are illustrated below: (no figure right now) Every knot is pass-equivalent to either the unknot or the trefoil; these two knots are not pass-equivalent and additionally, the right- and left-handed trefoils are pass-equivalent. Now we can define the Arf invariant of a knot to be 0 if it is pass-equivalent to the unknot, or 1 if it is pass-equivalent to the trefoil. This definition is equivalent to the one above. Vaughan Jones showed that the Arf invariant can be obtained by taking the partition function of a signed planar