Concept Hierarchy Extraction from Legal Literature

Due to the ever-increasing amount of legal regulations, it became an interest of scholars to find ways of capturing domain-relevant knowledge and facilitate the navigation in legal text corpora. Furthermore, the contextual nature of legislation requires enhanced semantic capabilities to identify relevant regulations for specific user needs. This work aims for collecting concept hierarchies from German literature in the legal domain which are then integrated into a knowledge base with multiple clusters, allowing for different perspectives and efficient lookups. Having references to regulations in the leaves of the concept tree and higher levels with an increasingly abstract context, the resulting hierarchies provide the basis for creating legal domain knowledge in German law. Starting with rule-based annotation, we cluster extracted references, given their context features derived from tables of contents and reasons for citing from various textbook formats. We study the expressiveness of the obtained reference context features. Since different authors have their own notion of hierarchy given by the table of contents, we propose a heterogeneous lightweight ontology allowing for the coexistence of similar, yet diverse concept hierarchies to dynamically determine the best fit for a user in a semisupervised setting. This approach is novel, since state-of-the-art ontologies are conventionally modeled under full integration and in a top-down manner, often not accounting for perspectives in knowledge representation.