 In particular, the conjecture is true whenever "G" or "H" is 4-colorable (since then the inequality χ("G" × "H") ≤ min {χ("G"), χ("H")} can only be strict when "G" × "H" is 3-colorable).In the remaining cases, both graphs in the tensor product are at least 5-chromatic and progress has only been made for very restricted situations.The following function (known as the "Poljak-Rödl function") measures how low the chromatic number of products of "n"-chromatic graphs can be.