dfa.py 文件源码

def has_finite_language(self):  # type: () -> bool
        """
        Returns True iff this DFA recognizes a finite (possibly empty) language.

        Based on decision procedure described here:
        http://math.uaa.alaska.edu/~afkjm/cs351/handouts/non-regular.pdf

        - Remove nodes which cannot reach an accepting state (see
          `_acceptable_subgraph` above).
        - Language is finite iff the remaining graph is acyclic.
        """
        return nx.is_directed_acyclic_graph(self._acceptable_subgraph)