@inproceedings{suzuki-etal-2003-hierarchical,
    title = "Hierarchical Directed Acyclic Graph Kernel: Methods for Structured Natural Language Data",
    author = "Suzuki, Jun  and
      Hirao, Tsutomu  and
      Sasaki, Yutaka  and
      Maeda, Eisaku",
    booktitle = "Proceedings of the 41st Annual Meeting of the Association for Computational Linguistics",
    month = jul,
    year = "2003",
    address = "Sapporo, Japan",
    publisher = "Association for Computational Linguistics",
    url = "https://preview.aclanthology.org/fix-sig-urls/P03-1005/",
    doi = "10.3115/1075096.1075101",
    pages = "32--39"
}