21. If loop-carried dependencies are left out, the dependency graph is a directed acyclic graph . 22. These types include trees, forests, directed graphs with multiple parents, and directed acyclic graphs . 23. Topological sorting of dependencies depends on the dependency graph being a directed acyclic graph ( DAG ). 24. Every arborescence is a directed acyclic graph ( DAG ), but not every DAG is an arborescence. 25. Nested group structures are studied in " hierarchical structure prediction " and with directed acyclic graphs . 26. An example of this intermediate representation could be something like an Abstract Syntax Tree or a Directed Acyclic Graph . 27. The set of communicating classes forms a directed, acyclic graph by inheriting the arrows from the original state space. 28. The structure should be a directed acyclic graph , with the reverse structure a mirror image of the forward structure. 29. A preorder that is antisymmetric no longer has cycles; it is a partial order, and corresponds to a directed acyclic graph . 30. However there are many other kinds of directed acyclic graph that are not formed by orienting the edges of an undirected acyclic graph.
