Empirical ontology design patterns and shapes from Wikidata

The ontology underlying the Wikidata knowledge graph (KG) has not been formalized. Instead, its semantics emerges bottom-up from the use of its classes and properties. Flexible guidelines and rules have been defined by the Wikidata project for the use of its ontology, however, it is still often difficult to reuse the ontology's constructs. Based on the assumption that identifying ontology design patterns from a knowledge graph contributes to make its (possibly) implicit ontology emerge, in this paper we present a method for extracting what we term empirical ontology design patterns (EODPs) from a knowledge graph. This method takes as input a knowledge graph and extracts the EODPs as sets of axioms/constraints involving the classes instantiated in the KG. These EODPs include data about the probability of such axioms/constraints to happen. We apply our method on two domain-specific portions of Wikidata, addressing the 'music' and 'art, architecture, and archaeology' domains, and we compare the empirical ontology design patterns we extract with the current support present in Wikidata. We show how these patterns can provide guidance for the use of the Wikidata ontology and its potential improvement, and can give an insight into the content of (domain-specific portions of) the Wikidata knowledge graph.