HOMFLY polynomial

Summary

The HOMFLY polynomial is an invariant of oriented links with values in Laurent polynomials in two variables. It is defined by a skein relation and contains both the Alexander polynomial and the Jones polynomial as special cases. Its name comes from the initials of Hoste, Ocneanu, Millett, Freyd, Lickorish and Yetter, who found it soon after the Jones polynomial. Przytycki and Traczyk found it independently, so it is also called the HOMFLYPT polynomial.