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Karl Hammar defended his PhD thesis on Ontology Design Patterns

On September 29, Karl Hammar successfully defended his PhD thesis entitled “Content Ontology Design Patterns: Qualities, Methods, and Tools”. The thesis was first presented by the opponent, professor Harald Sack, FIZ, Karlsruhe, Germany, who then continued to discuss the research results and future ideas with Karl. The three members of the examining committee then continued the discussion with Karl, before unanimously deciding to approve his thesis and award the PhD degree to Karl. At which point we could all congratulate him to a an interesting defence and an excellent thesis. In particular, his three supervisors, Henrik Eriksson (LiU), Eva Blomqvist (LiU) and Vladimir Tarassov (JTH) were of course the first to congratulate him, followed by colleagues and family.

Karl Hammar’s research has aimed to combine quantitative and qualitative research methods, primarily based on five ontology engineering projects involving inexperienced ontologists, studying how Ontology Design Patterns (ODPs) can support that specific group of users. A series of ontology engineering workshops and surveys provided data about developer preferences regarding ODP features and quality, ODP usage methodology, and ODP tooling needs. Other data sources were ontologies and ODPs published on the web, which have been studied in detail. To evaluate tooling improvements, experimental approaches provided data from comparison of new tools and techniques against established alternatives.

The analysis of the gathered data resulted in a set of measurable quality indicators that cover aspects of ODP documentation, formal representation or axiomatisation, and usage by ontologists. These indicators highlight quality trade-offs: for instance, between ODP Learnability and Reusability, or between Functional Suitability and Performance Efficiency. These are things that ontology engineers need to keep in mind when using ODPs in their ontologies, and in particular if they are inexperienced ontologists. Furthermore, the results demonstrated a need for ODP tools that support three novel property specialisation strategies, and highlighted the preference of inexperienced developers for template-based ODP instantiation, neither of which were supported in prior tooling. The studies also resulted in improvements to ODP search engines based on ODP-specific attributes. Finally, the analysis showed that a specific ontology engineering methodology, the eXtreme Design (XD), should include guidance for developer roles and responsibilities in ontology engineering projects, suggestions on how to reuse existing ontology resources, and approaches for adapting XD to project-specific contexts. Karl therefore proposed a new version of the XD methodology, specifically covering these aspects.

The thesis can be found here.



 

 

 

 

 

 

 

Congratulations Karl!

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Zlatan Dragisic defended his PhD Thesis on Completion of Ontologies and Ontology Networks

Yesterday, on September 26, our PhD candidate Zlatan Dragisic defended successfully his thesis with the title “Completion of Ontologies and Ontology Networks.” The thesis makes several contributions: First, the problem of completing the is-a structure in ontologies is formalized as an abductive reasoning problem and the thesis introduces algorithms as well as systems for dealing with the problem. Regarding the completion of alignments between ontologies, the thesis provides a performance study of systems that participated in the Ontology Alignment Evaluation Initiative, and an approach to reduce the search space when generating such alignments. Next, the thesis reports a broad study of state-of-the-art ontology alignment systems in terms of user involvement during the completion process and, in particular, the impact of user errors in this process. Finally, the thesis introduces an approach to integrate ontology completion and ontology alignment into an existing ontology development methodology.

Zlatan’s work on the thesis was supervised by Patrick Lambrix, and co-supervised by Nahid Shahmehri, Marco Kuhlmann, and Fang Wei-Kleiner. The opponent was Erhard Rahm from the University of Leipzig, Germany. The examination committee consisted of Asuncion Gomez-Perez from Universidad Politecnica de Madrid, Jerome Euzenat from INRIA and Graham Kemp from Chalmers University of Technology. Magnus Bång from Linköping University was backup examination committee member.

Find the thesis in the Diva portal.

Well done Zlatan! Congratulations!

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Emanuele Della Valle (Politecnico di Milano) will talk at LiU about Stream Reasoning

On October 5 (Thursday), Emanuele Della Valle of Politecnico di Milano, Italy, will give a Semantic Web related talk at LiU. The title of his talk is:

Stream Reasoning: A Summary of Ten Years of Research and a Vision for the Next Decade

Abstract: Stream reasoning studies the application of inference techniques to data characterised by being highly dynamic. It can find application in several settings, from Smart Cities to Industry 4.0, from Internet of Things to Social Media analytics. This year stream reasoning turns ten, and this talk analyses its growth. In the first part, it traces the main results obtained so far, by presenting the most prominent studies. It starts by an overview of the most relevant studies developed in the context of semantic web, and then it extends the analysis to include contributions from adjacent areas, such as database and artificial intelligence. Looking at the past is useful to prepare for the future: the second part presents a set of open challenges and issues that stream reasoning will face in the next future.

Time and date: 9.00am, October 5, 2017

Location: Campus Valla, Building E, Room “Alan Turing”

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Dagstuhl seminar on Federated Semantic Data Management

During the last week of June, I co-organized a Dagstuhl seminar on Federated Semantic Data Management together with Maria-Esther Vidal and Johann-Christoph Freytag. It was a very intense week with a packed schedule and almost no time to catch some breath (exactly like how a Dagstuhl seminar should be I guess 😉

To start with, we had scheduled a few short, survey-style talks on a number of topics related to the seminar. In particular, these talks covered:

While these talks were meant to establish a common understanding of key concepts and terminology, the major focus of the seminar was on discussions and working groups. To this end, we had invited a good mix of participants from the Semantic Web field, from Databases, as well as from application areas. Due to this mix, we ended up on several occasions and in different constellations discussing and reflecting in depth the fundamental assumptions and the core ideas of federated semantic data management. These general discussions and reflections kept re-emerging not only during the sessions, but also during the meals, the coffee breaks, and the evenings in Dagstuhl’s wine cellar. In my opinion, clearly articulating and repeatedly arguing about these assumptions and ideas was a long-needed discussion to be had in the community. After this week, I would guess that many of the participants have a much clearer understanding of what federated semantic data management can and should be, and I am certain that this understanding will be reflected in the reports that the working groups are preparing.

Speaking of working groups, the seminar was structured around four topics addressed by four separate working groups who came together occasionally to report on their progress and obtain feedback from the other groups. The topics were:

  • RDF and graph data models
  • Federated query processing
  • Access control and privacy
  • Use cases and applications

Each of the working groups is currently preparing a summary of their discussions and results. These summaries will become part of our Dagstuhl report (to be published some time in August if all goes well). In addition to this report, we are planning to document the discussions and the results of the seminar in a collection of more detailed publications.

What’s next? We have some ideas to keep the momentum and to advance the discussions around the seminar topics in a more continuous community process. Stay tuned.

Olaf

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LiU Semantic Web group at ESWC2017

This week a couple of us have been at ESWC2017 in Portoroz, Slovenia. Eva Blomqvist was the general chair of the conference this year, hence, this was the culmination of a whole year of hard work for her. Olaf Hartig is the proceedings chair (proceedings part 1 and 2). He could not attend the conference this year, but has done great job with the Springer proceedings, and the upcoming post-proceedings volume with poster and demo papers among other things. In addition to this, Karl Hammar, was one of the organisers of the Modular Ontology Modeling with Ontology Design Patterns tutorial, together with Pascal Hitzler, Adila A. Krisnadhi, Agnieszka Lawrynowicz and Monika Solanki. In particular, Karl ran the hands-on session with his tool for ODP-based modelling in WebProtégé (called XDP). Finally, Henrik Eriksson, presented our EU-funded project VALCRI in the project networking session, and in the poster session.

The overall conference was interesting as always, and included a lot of networking opportunities, as well as interesting work to take a closer look at. A quick summary of some of the major events:

Crosbie

Kevin Crosbie, from Ravenpack, the first keynote speaker talking about how to model events in order to use them for predicting financial markets. Very interesting talk, describing how Ravenpack work with their data products and apply technologies very similar to Semantic Web, although technically not using the W3C standards, such as RDF.

Panel

At the end of the first day, Aldo Gangemi chaired a panel about the future of academic publishing, discussing the challenges and opportunities that lie ahead. It is clear that something needs to be done about both the reviewing situation in our field, the open access issue, and we want more focus on “eating our own dog food”. The discussions were also related to the paper that later won the best student paper award, on Linked Data Notifications.

Sheridan

Second keynote speaker, John Sheridan, from the National Archives in the UK, described how the National Archives heavily rely on Semantic Web technologies and standards to solve their archiving tasks. However there are also challenges of course, which can hopefully be solved by working together: academia and society at large. Particularly interesting for us at LiU to hear that the National Archives is in great need of a better solution for modelling trust and uncertainty in their data, which could be a potential use case for the recent research results on RDF* and SPARQL* by Olaf Hartig.

Dinner

Nice conference dinner at the beach, and a chance for the general chair to thank all the people in the organising committee.

Poster

Poster session with lots of interesting interactions and discussion, here with Diego Reforgirato, who later won both the best poster and best demo awards.

Unfortunately, we did not take any picture of the last keynote, Lora Aroyo, who gave a very interesting keynote on the last day. She started with an overview of the evolution of the field, pointing out that studying and using people to acquire knowledge has always been a central part of our research. However, by over simplifying, and trying to fit every answer into yes/no categories, we can introduce wrong conclusions. She means that we need to be aware of ambiguity and diversity in opinions, that there is usually not one true answer, and instead turn that to our advantage. Lora showed a vector-based model to represent diversity in opinions.

Finally, Aldo Gangemi will be the next general chair of ESWC in 2018, and he made a series of interesting promises for the next year, among others: double-open review process, improvements in the online pre-prints of the proceedings and the dataset, a resources track and an industry session á la ISWC, and better music in the social events. We all wish him the best of luck with the next conference, and we are excited to see all the innovations next year!