a1 Department of Mathematics, University of Toronto, Toronto, Canada M5S 1A1
a2 Department of Mathematics, Warsaw University, Warsaw, Poland 00901
If PL(v,z) = Σbi(v)zi is the skein polynomial of a link L, and D = D1 * D2 is the diagram which is a planar star (Murasugi) product of D1 and D2 then bϕ(D)(v) = bϕ(D1)·bϕ(D2)(v) where ϕ(D) = n(D)– (s(D) – 1) and n(D) denotes the number of crossings of D, and s(D) is the number of Seifert circles of D.
(Received July 11 1988)
(Revised October 24 1988)
(Online publication June 28 2011)