Hierarchical Directed Acyclic Graph Kernel: Methods for Structured Natural Language Data Jun Suzuki author Tsutomu Hirao author Yutaka Sasaki author Eisaku Maeda author 2003-07 text Proceedings of the 41st Annual Meeting of the Association for Computational Linguistics Association for Computational Linguistics Sapporo, Japan conference publication suzuki-etal-2003-hierarchical 10.3115/1075096.1075101 https://aclanthology.org/P03-1005/ 2003-07 32 39