The RDF2vec Family of Knowledge Graph Embedding Methods

Tracking #: 3319-4533

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Jan Portisch1
Heiko Paulheim

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Claudia d'Amato

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Knowledge graph embeddings represent a group of machine learning techniques which project entities and relations of a knowledge graph to continuous vector spaces. RDF2vec is a scalable embedding approach rooted in the combination of random walks with a language model. It has been successfully used in various applications. Recently, multiple variants to the RDF2vec approach have been proposed, introducing variations both on the walk generation and on the language modeling side. The combination of those different approaches has lead to an increasing family of RDF2vec variants. In this paper, we evaluate a total of twelve RDF2vec variants on a comprehensive set of benchmark models, and compare them to seven existing knowledge graph embedding methods from the family of link prediction approaches. Besides the established GEval benchmark introducing various downstream machine learning tasks on the DBpedia knowledge graph, we also use the new DLCC (Description Logic Class Constructors) benchmark consisting of two gold standards, one based on DBpedia, and one based on synthetically generated graphs. The latter allows for analyzing which ontological patterns in a knowledge graph can actually be learned by different embedding. With this evaluation, we observe that certain tailored RDF2vec variants can lead to improved performance on different downstream tasks, given the nature of the underlying problem, and that they, in particular, have a different behavior in modeling similarity and relatedness. Our experiments on a gold standard created from the real-world knowledge graph DBpedia reveal that all approaches perform surprisingly well due to correlating signals. On a synthetic dataset without such correlating signals, in contrast, we can observe that there are quite a few classes which are hard to learn for all inspected knowledge graph embedding methods. For RDF2vec, we can observe that walk strategies influence the balance of similarity and relatedness.
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