September 9 – 14 , 2018, Dagstuhl Seminar 18371

Knowledge Graphs: New Directions for Knowledge Representation on the Semantic Web


Piero Andrea Bonatti (University of Naples, IT)
Stefan Decker (RWTH Aachen, DE)
Axel Polleres (Wirtschaftsuniversität Wien, AT)
Valentina Presutti (CNR – Rome, IT)

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Dagstuhl Report, Volume 8, Issue 9 Dagstuhl Report
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In 2001 Berners-Lee et al. stated that "The Semantic Web is an extension of the current web in which information is given well-defined meaning, better enabling computers and people to work in cooperation."

The time since the publication of the paper and creation of the foundations for the Semantic Web can be roughly divided in three phases: The first phase focused on bringing Knowledge Representation to Web Standards, e.g., with the development of OWL. The second phase focused on data management, linked data and potential applications. In the third, more recent phase, with the emergence of real world applications, emphasis is put again on the notion of Knowledge, while maintaining the large graph aspect: Knowledge Graphs have a large number of applications like semantic search based on entities and relations, disambiguation of natural language, deep reasoning (e.g. IBM Watson), machine reading (e.g. text summarization), entity consolidation for Big Data, and text analytics. Others are exploring the application of Knowledge Graphs in industrial and scientific applications.

The shared characteristic by all these applications can be expressed as a challenge: the capability of combining diverse reasoning methods and knowledge representations while guaranteeing the required scalability, according to the reasoning task at hand. Methods include: Temporal knowledge and reasoning, Integrity constraints, Probabilistic and fuzzy reasoning, Analogical reasoning, Reasoning with Prototypes and Defeasible Reasoning, Cognitive Frames, Ontology Design Patterns (ODP), and Neural Networks and other machine learning models.

With this Dagstuhl Seminar, we intend to bring together researchers that have faced and addressed the challenge of combining diverse reasoning methods and knowledge representations in different domains and for different tasks with Knowledge Graphs and Linked Data experts with the purpose of drawing a sound research roadmap towards defining scalable Knowledge Representation and Reasoning principles within a unifying Knowledge Graph framework. Driving questions include:

  • What are fundamental Knowledge Representation and Reasoning methods for Knowledge Graphs?
  • How should the various Knowledge Representation, logical symbolic reasoning, as well as statistical inference methods be combined and how should they interact?
  • What are the roles of ontologies for Knowledge Graphs?
  • How can existing data be ingested into a Knowledge Graph?

We intend to start from use cases where (i) different techniques have been hybridized for addressing tasks or (ii) where existing Semantic Web technologies were insufficient. The goal is to identify and formalize use cases and draft potential procedural, representational and reasoning patterns that may become the topics of a workshop series and/or subjects for later standardization efforts, similar to how the standardization of OWL can be traced back to the “Semantics for the Web [Dagstuhl] Seminar” in 2000.

As a result of the seminar we plan to collect such different representational approaches and their possible combinations in a systematic manner and derive a joint research roadmap for new directions of Knowledge Representation for the Semantic Web as such, including discussions on the right balance between standardization, development of bestpractices, and open questions for more fundamental research.

The Seminar will allow for cross-fertilization between research on different Knowledge Representation mechanisms, and will also help to identify the requirements for Knowledge Representation research originating from the deployment of Knowledge graphs and the discovery of new research problems motivated by applications. So, we foresee the establishment of a new research direction, which focuses on how to combine the results from knowledge representation research in several subfields for joint use for Knowledge Graphs and Data on the Web.

  Creative Commons BY 3.0 DE
  Piero Andrea Bonatti, Stefan Decker, Axel Polleres, and Valentina Presutti


  • Artificial Intelligence / Robotics
  • Semantics / Formal Methods
  • World Wide Web / Internet


  • Semantic Web
  • Knowledge Representation
  • Ontologies
  • Linked Data
  • Knowledge Graphs

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