Tom fool's knot Tom fool's knot The Tom fool's knot is sometimes considered a handcuff knot but is somewhat inferior for this purpose to the knot which usually bears that name. It is a good knot with which to commence a slightly fancy sheepshank. It is also used as a trick knot due to the speed with which it can be made. Tom fool's knot is believed to be the knot "epankylotos brokhos" described by the 1st Century Greek physician Heraklas. It is formed by making two loops, not exactly overlaying each other. The inner half of each hitch or loop is pulled
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