Applying a Multi-Level Modeling Theory to Assess Taxonomic Hierarchies in Wikidata

Wikidata captures structured data on a number of subject domains, managing, among others, the information underlying Wikipedia and other Wikimedia projects. Wikidata serves as a repository of structured data, whose purpose is to support the consistent sharing and linking of data on the Web. To support these purposes, it is key that Wikidata is built on consistent data models and representation schemas, which are constructed and managed in a collaborative platform. In this paper, we address the quality of taxonomic hierarchies in Wikidata. We focus on taxonomic hierarchies with entities at different classification levels (particular individuals, types of individuals, types of types of individuals, etc.). We use an axiomatic theory for multi-level modeling to analyze current Wikidata content, and identify a significant number of problematic classification and taxonomic statements. The problems seem to arise from an inadequate use of instantiation and subclassing in certain Wikidata hierarchies.