Recognition of a Spanning Tree of Directed Acyclic Graphs by Tree Automata

摘要

In this paper, we study tree automata for directed acyclic graphs (DAGs). We define the movement of a tree automaton on a DAG so that a DAG is accepted by a tree automaton if and only if a DAG has a spanning tree accepted by a tree automaton. The NP-completeness of the membership problem of DAGs for a tree automaton is shown, and a linear-time recognition algorithm of series-parallel graphs for a tree automaton is presented.