A characterization of normal fraternally orientable perfect graphs

While the famous Bergeʹs Strong Perfect Graph Conjecture remains a major unsolved problem in Graph Theory, the following alternative characterization of perfect graphs was conjectured in 1982 by C. Berge and P. Duchet: A graph G is perfect if and only if any normal orientation of G is kernel-perfect. In this paper I prove the validity of a version of this conjecture for graphs which accept a normal fraternal orientation.