title: BIOSMILE: a semantic role labeling system for biomedical verbs using a maximum-entropy model with automatically generated template features.
abstract: BACKGROUND
  Bioinformatics tools for automatic processing of biomedical literature are invaluable for both the design and interpretation of large-scale experiments. Many information extraction (IE) systems that incorporate natural language processing (NLP) techniques have thus been developed for use in the biomedical field. A key IE task in this field is the extraction of biomedical relations, such as protein-protein and gene-disease interactions. However, most biomedical relation extraction systems usually ignore adverbial and prepositional phrases and words identifying location, manner, timing, and condition, which are essential for describing biomedical relations. Semantic role labeling (SRL) is a natural language processing technique that identifies the semantic roles of these words or phrases in sentences and expresses them as predicate-argument structures. We construct a biomedical SRL system called BIOSMILE that uses a maximum entropy (ME) machine-learning model to extract biomedical relations. BIOSMILE is trained on BioProp, our semi-automatic, annotated biomedical proposition bank. Currently, we are focusing on 30 biomedical verbs that are frequently used or considered important for describing molecular events.
  
  
  RESULTS
  To evaluate the performance of BIOSMILE, we conducted two experiments to (1) compare the performance of SRL systems trained on newswire and biomedical corpora; and (2) examine the effects of using biomedical-specific features. The experimental results show that using BioProp improves the F-score of the SRL system by 21.45% over an SRL system that uses a newswire corpus. It is noteworthy that adding automatically generated template features improves the overall F-score by a further 0.52%. Specifically, ArgM-LOC, ArgM-MNR, and Arg2 achieve statistically significant performance improvements of 3.33%, 2.27%, and 1.44%, respectively.
  
  
  CONCLUSIONS
  We demonstrate the necessity of using a biomedical proposition bank for training SRL systems in the biomedical domain. Besides the different characteristics of biomedical and newswire sentences, factors such as cross-domain framesets and verb usage variations also influence the performance of SRL systems. For argument classification, we find that NE (named entity) features indicating if the target node matches with NEs are not effective, since NEs may match with a node of the parsing tree that does not have semantic role labels in the training set. We therefore incorporate templates composed of specific words, NE types, and POS tags into the SRL system. As a result, the classification accuracy for adjunct arguments, which is especially important for biomedical SRL, is improved significantly.
authors.affiliation: Institute of Information Science, Academia Sinica, Nankang, Taipei 115, Taiwan, PRoC. thtsai@iis.sinica.edu.tw
authors.forename: Richard Tzong-Han
authors.initials: RT
authors.lastname: Tsai
authors.forename: Wen-Chi
authors.initials: WC
authors.lastname: Chou
authors.forename: Ying-Shan
authors.initials: YS
authors.lastname: Su
authors.forename: Yu-Chun
authors.initials: YC
authors.lastname: Lin
authors.forename: Cheng-Lung
authors.initials: CL
authors.lastname: Sung
authors.forename: Hong-Jie
authors.initials: HJ
authors.lastname: Dai
authors.forename: Irene Tzu-Hsuan
authors.initials: IT
authors.lastname: Yeh
authors.forename: Wei
authors.initials: W
authors.lastname: Ku
authors.forename: Ting-Yi
authors.initials: TY
authors.lastname: Sung
authors.forename: Wen-Lian
authors.initials: WL
authors.lastname: Hsu
mesh_terms: D001185:Artificial Intelligence; D019295:Computational Biology / Q000379:methods*; D003198:Computer Simulation; D016247:Information Storage and Retrieval / Q000379:methods*; D008962:Models, Theoretical; D009323:Natural Language Processing; D010506:Periodicals as Topic; D012660:Semantics; D018875:Vocabulary, Controlled