On knot 2-adjacency

We study the relations between the related crossings and the second and fourth coefficients of Conway polynomials of 2-adjacent knots, the relations between the crossings and the extreme coefficients of the related Homfly polynomials and explain how these coefficients determine the signs of the crossings. We give some interesting properties of the related Homfly polynomials. In fact, we show that 17 knots of the 19 exceptions given in A. Stoimenowʹs paper are not 2-adjacent.