Ferrers digraphs and threshold graphs

AbstractWe deduce a set of known characterizations of threshold graphs (Theorem 3) from a set of characterizations of Ferrers digraphs (Theorem 1) by investigating the connection between symmetric Ferrers digraphs and threshold graphs. A direct proof of Theorem 3 is easier than the one provided in here, but the purpose of this paper is to view Theorem 1 as an extension of Theorem 3 to the directed case (this extension point of view still holds on an algorithmic ground)