In this paper we define a link homotopy invariant of spatial graphs based on the second degree coefficient of the Conway polynomial of a knot.
@article{urn:eudml:doc:43959, title = {Link homotopy invariants of graphs in R3.}, journal = {Revista Matem\'atica de la Universidad Complutense de Madrid}, volume = {7}, year = {1994}, pages = {129-144}, zbl = {0818.57005}, mrnumber = {MR1277334}, language = {en}, url = {http://dml.mathdoc.fr/item/urn:eudml:doc:43959} }
Taniyama, Kouki. Link homotopy invariants of graphs in R3.. Revista Matemática de la Universidad Complutense de Madrid, Tome 7 (1994) pp. 129-144. http://gdmltest.u-ga.fr/item/urn:eudml:doc:43959/