This dissertation addresses several problems in the context of publishing and consuming Linked Data. It describes these problems from the perspectives of three stakeholders: the Linked Data provider, developer and scientist. The Linked Data provider is faced with impractical data re-use and costly Linked Data hosting solutions. Developers face difficulties in finding, navigating and using Linked Datasets. Scientists lack the resources and methods to evaluate their work on Linked Data at large.
This dissertation presents a number of novel approaches that address these issues, such as:
The LOD Laundromat: a centralized service that re-publishes cleaned, queryable and structurally annotated Linked Datasets. In 2015 the Laundromat was awarded first prize in the Dutch national Linked Open Data competition, and third prize in the European equivalent.
SampLD: A relevance-based sampling algorithm that enables publishers to decrease Linked Data hosting costs;
YASGUI: A feature-rich query editor for accessing SPARQL endpoints;
LOD Lab: An evaluation paradigm that enables scientists to increase the breadth and scale of their Linked Data evaluations.
This work provides a unique overview of problems related to publishing and consuming Linked Data. The novel approaches presented here improve the state-of-the-art for Linked Data publishers, developers and scientists, and are a step towards a web of Linked Data that is more accessible and technically scalable.
It has been an interesting and enjoyable last four years. It is not often that you are allowed to work in such a warm and social environment, surrounded by smart people, and with so much freedom to do fun things.
This great experience can for a large part be contributed to my three supervisors, Frank van Harmelen, Rinke Hoekstra and Stefan Schlobach. I could not wish for a better combination of characters and skills in my supervisors. Thanks to Rinke, for his keen eye and practical advice on topics such as presentations, scientific writing, research in general, and leveraging the goals of a PhD with those of a scientific project. Thanks to Stefan, for the fun discussions, cups of coffee, and enriching my writing skills with some ‘youthful arrogance’. And thanks to Frank, for both pushing me to keep my eye on the prize and giving me a lot of freedom in my research at the same time. Wouter Beek, with whom I enjoyed sharing the office, deserves a special mention as well. I was lucky to work with Wouter, considering that our skills are largely complementary and our collaboration has proved quite productive. I am happy that we will continue collaborating after this thesis.
Regarding my thesis and its defence, I thank the committee (Sören Auer, Victor de Boer, Stefan Decker, Geert-Jan Houben and Peter Mika) for having read and accepted it.
I also thank all the people from the KRR&R and the Web & Media groups. Thanks Chris for the exhausting tennis matches, and sorry for distracting you so much. Thanks Albert for all the short walks outside. Filip, I hope you find the time to continue the nice projects that started in our room. And Archana, sorry for the workspace disruptions. Be gentle in your acknowledgements!
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