1788, in linguistics, from Greek di- "twice" (see di- (1)) + -graph "something written," from Greek graphe "writing," from graphein "to write, express by written characters," earlier "to draw, represent by lines drawn" (see -graphy). In mathematics, from 1955, a contraction of directed graph.
1. A digraph D is unilateral.
2. We shall abbreviate'directed graph'to digraph.
3. A digraph D is hamiltonian if D contains a hamilton directed cycle.
4. There fore we study the kings of locally semicomplete digraph by its characterization.