French bowline French bowline Some consider that a French bowline is the same as a Portuguese bowline, i.e. a bowline with two loops that can be used as a bosun's chair. A different knot is however also known as a French bowline. This form of bowline is similar to a standard bowline but there are several loops so that there is less likelihood of damage to a delicate object secured by the bowline. As with a standard bowline, the knot cannot tighten. Pressure is distributed over a wider area than in the case of a standard bowline. The main advantage of this
Signature of a knot Signature of a knot The signature of a knot is a topological invariant in knot theory. It may be computed from the Seifert surface. Given a knot "K" in the 3-sphere, it has a Seifert surface "S" whose boundary is "K". The Seifert form of "S" is the pairing formula_1 given by taking the linking number formula_2 where formula_3 and formula_4 indicate the translates of "a" and "b" respectively in the positive and negative directions of the normal bundle to "S". Given a basis formula_5 for formula_6 (where "g" is the genus of the surface) the Seifert form can be