Learning Combination Features with L1 Regularization Daisuke Okanohara author Jun’ichi Tsujii author 2009-06 text Proceedings of Human Language Technologies: The 2009 Annual Conference of the North American Chapter of the Association for Computational Linguistics, Companion Volume: Short Papers Mari Ostendorf editor Michael Collins editor Shri Narayanan editor Douglas W Oard editor Lucy Vanderwende editor Association for Computational Linguistics Boulder, Colorado conference publication okanohara-tsujii-2009-learning https://aclanthology.org/N09-2025/ 2009-06 97 100