Continuum many universal Horn classes of graphs of bounded chromatic number
It was shown previously by X. Caicedo that there are continuum many universal Horn classes of graphs. However, the question whether there are continuum many universal Horn classes whose members are of a bounded chromatic number was left open. The author exhibits continuum many of such classes between every interval of colour families above the class of 2-colorable graphs.
scientific article; zbMATH DE number 1407106