Let P(G;x,y) be the number of vertex colorings φ : V →{1, ...,x} of an undirected graph G = (V,E) such that for all edges {u,v} ∈ E the relations φ(u)≤ y and φ(v)≤ y imply φ(u) 6= φ(v). We show that P(G;x,y) is a polynomial in x and y which is closely related to Stanley’s chromatic symmetric function, and which simultaneously generalizes the chromatic polynomial, the independence polynomial, an...