It is known that the chromatic number of a graph G = (V,E) with V = {1
,2,..., n} exceeds k iff the graph polynomial f(G) = Pi(ij is an eleme
nt of E,t<j) (c(1) - x(j)) lies in certain ideals. We describe a short
proof of this result, using Ore's version of Hajos' theorem. We also
show that a certain weighted sum over the proper k-colorings of a grap
h can be computed from its graph polynomial in a simple manner. (C) 19
97 Academic Press.