11. A rooted tree itself has been defined by some authors as a directed graph . 12. For example, they allow representation of a directed graph with trees on the nodes. 13. In the structural brain connectivity type, the connectivity is a sparse and directed graph . 14. These types include trees, forests, directed graphs with multiple parents, and directed acyclic graphs. 15. The converse is not true : most directed graphs are neither reflexive nor transitive. 16. A filter graph in multimedia processing is a directed graph . 17. In game theory, a "'game tree "'is a directed graph whose edges are moves. 18. It was studied on general directed graphs by Boldi and Vigna ( 2014 ). 19. The model represents a system as directed graph , where vertices are either subjects or objects. 20. An alternative representation of such a function is a directed graph called a reachability graph.
