Kauffman polynomial

From Wikipedia, the free encyclopedia

The Kauffman polynomial is a 2-variable knot polynomial due to Louis Kauffman. It is initially defined on a link diagram as

where w(K) is the writhe of the link diagram and L(K) is a polynomial in a and z defined on diagrams by the following properties:

• L(O) = 1 (O is the unknot)
• 
• L is unchanged under type II and III Reidemeister moves

Here s is a strand and s_r (resp. ) is the same strand with a right-handed (resp. left-handed) curl added (using a type I Reidemeister move).

Additionally L must satisfy Kauffman's skein relation:

The pictures represent the L polynomial of the diagrams which differ inside a disc as shown but are identical outside.

Kauffman showed that L exists and is a regular isotopy invariant of unoriented links. It follows easily that F is an ambient isotopy invariant of oriented links.

The Jones polynomial is a special case of the Kauffman polynomial, as the L polynomial specializes to the bracket polynomial. The Kauffman polynomial is related to Chern-Simons gauge theories for SO(N) in the same way that the HOMFLY polynomial is related to Chern-Simons gauge theories for SU(N) (see Witten's article "Quantum field theory and the Jones polynomial", in Commun. Math. Phys.)

[edit] References

• Louis Kauffman, On Knots, (1987), ISBN 0-691-08435-1

[edit] External links

• Springer EoM entry for Kauffman polynomial
• Knot Atlas entry for Kauffman polynomial