This work was partially supported by the National Natural Science Foundation of China(Grant No.10471078);the Special Research Foundation for the Doctoral Program of Higher Education of China(Grant No.20040422004);Hong Kong Research Grants Council(Grant No.CityU 1056/01E).
We prove that, for any given vertexν* in a series-parallel graph G, its edge set can be partitioned into k= min{k′(G) + 1,δ(G)} subsets such that each subset covers all the vertices of G possibly except forν*, wh...