I am an assistant professor (UD) at the User-Centric Data Science group at the Computer Science department of the Vrije Universiteit Amsterdam (VU). I am also a senior research fellow at Netherlands Institute for Sound and Vision. In my research, I combine (Semantic) Web technologies with Human-Computer Interaction, Knowledge Representation and Information Extraction to tackle research challenges in various domains. These include Cultural Heritage, Digital Humanities and ICT for Development (ICT4D). More information on these projects can be found on this site or through my CV .

Interconnect Project kickoff

On 1 October 2019, the Horizon2020 Interconnect project has started. The goal of this huge and ambitious project is to achieve a relevant milestone in the democratization of efficient energy management, through a flexible and interoperable ecosystem where distributed energy resources can be soundly integrated with effective benefits to end-users.

To this end, its 51 partners (!) will develop an interoperable IOT and smart-grid infrastructure, based on Semantic technologies, that includes various end-user services. The results will be validated using 7 pilots in EU member states, including one in the Netherlands with 200 appartments.

The role of VU is to develop in close collaboration with TNO extend and validating the SAREF ontology for IOT as well as and other relevant ontologies. VU will lead a task on developing Machine Learning solutions on Knowledge graphs and extend the solutions towards usable middle layers for User-centric ML services in the pilots, specifically in the aforementioned Dutch pilot, where VU will collaborate with TNO and VolkerWessel iCity and Hyrde.

Interconnect team photo, taken at the location of the kickoff meeting: the FC Porto stadium

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Semantics2019 trip report

Last week, I attended the SEMANTiCS2019 conference in Karlsruhe, Germany. This was the 15th edition of the conference that brings together Academia and Industry around the topic of Knowledge Engineering and Semantic Technologies and the good news was that this year’s conference was the biggest ever with 426 unique participants.

I was not able to join the workshop day or the dbpedia day on monday and thursday respectively, but was there for the main programme. The first day opened with a keynote from Oracle’s Michael J. Sullivan about Hybrid Knowledge Management Architecture and how Oracle is betting on Semantic Technology to work in combination with data lake architectures.

The 2nd keynote by Michel Dumontier of Maastricht University covered the principles of FAIR publishing of data and current avances in actually measuring FAIRness of datasets.

During one of the parallel sessions I attended the presentation of the eventual best paper winner Robin Keskisärkkä, Eva Blomqvist, Leili Lind, and Olaf Hartig. RSP-QL*: Enabling Statement-Level Annotations in RDF Streams . This was a very nice talk for a very nice and readable paper. The paper describes the combination of current RDF stream reasoning language RSP-QL and how it can be extended with the principles of RDF* that allow for statements about statements without traditional re-ification. The paper nicely mixes formal semantics, an elegant solution, working code, and a clear use case and evaluation. Congratulations to the winners.

Other winners included the best poster, which was won by our friends over at UvA.

The second day for me was taken up by the Special Track on Cultural Heritage and Digital Humanities, which consisted of research papers, use case presentations and posters that relate to the use of Semantic technologies in this domain. The program was quite nice, as the embedded tweets below hopefully show.

All in all, this years edition of SEMANTICS was a great one, I hope next year will be even more interesting (I will be general chairing it).

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Linked Art Provenance

In the past year, together with Ingrid Vermeulen (VU Amsterdam) and Chris Dijkshoorn (Rijksmuseum Amsterdam), I had the pleasure to supervise two students from VU, Babette Claassen and Jeroen Borst, who participated in a Network Institute Academy Assistant project around art provenance and digital methods. The growing number of datasets and digital services around art-historical information presents new opportunities for conducting provenance research at scale. The Linked Art Provenance project investigated to what extent it is possible to trace provenance of art works using online data sources.

Caspar Netscher, the Lacemaker, 1662, oil on canvas. London: the Wallace Collection, P237

In the interdisciplinary project, Babette (Art Market Studies) and Jeroen (Artificial Intelligence) collaborated to create a workflow model, shown below, to integrate provenance information from various online sources such as the Getty provenance index. This included an investigation of potential usage of automatic information extraction of structured data of these online sources.

This model was validated through a case study, where we investigate whether we can capture information from selected sources about an auction (1804), during which the paintings from the former collection of Pieter Cornelis van Leyden (1732-1788) were dispersed. An example work , the Lacemaker, is shown above. Interviews with various art historian validated the produced workflow model.

The workflow model also provides a basic guideline for provenance research and together with the Linked Open Data process can possibly answer relevant research questions for studies in the history of collecting and the art market.

More information can be found in the Final report

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Remembering Maarten van Someren

Last week, while abroad, I received the very sad news that Maarten van Someren passed away. Maarten was one of the core teachers and AI researchers at Universiteit van Amsterdam for 36 years and for many people in AI in the Netherlands, he was a great teacher and mentor. For me personally, as my co-promotor he was one of the persons who shaped me into the AI researcher and teacher I am today.

Maarten van Someren at my PhD defense (photo by Jochem Liem)

Before Maarten asked me to do a PhD project under his and Bob Wielinga‘s supervision, I had known him for several years as UvA’s most prolific AI teacher. Maarten was involved in many courses, (many in Machine Learning) and in coordinating roles. I fondly look back at Maarten explaining Decision Trees, the A* algorithm and Vapnik–Chervonenkis dimensions. He was one of the staff members who really was a bridge between research and education and gave students the idea that we were actually part of the larger AI movement in the Netherlands.

After I finished my Master’s at UvA in 2003, I bumped into Maarten in the UvA elevator and he asked me whether I would be interested in doing a PhD project on Ontology Learning. Maarten explained that I would start out being supervised by both him and Bob Wielinga, but that after a while one of them would take the lead, depending on the direction the research took. In the years that followed, I tried to make sure that direction was such that both Bob and Maarten remained my supervisors as I felt I was learning so much from them. From Maarten I learned how to always stay critical about the assumptions in your research. Maarten for example kept insisting that I explain why we would need semantic technologies in the first place, rather than taking this as an assumption. Looking back, this has tremendously helped me sharpen my research and I am very thankful for his great help. I was happy to work further with him as a postdoc on the SiteGuide project before moving to VU.

In the last years, I met Maarten several times at shared UvA-VU meetings and I was looking forward to collaborations in AI education and research. I am very sad that I will no longer be able to collaborate with him. AI in the Netherlands has lost a very influential person in Maarten.

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Exploring Automatic Recognition of Labanotation Dance Scores

[This post describes the research of Michelle de Böck and is based on her MSc Information Sciences thesis.]

Digitization of cultural heritage content allows for the digital archiving, analysis and other processing of that content. The practice of scanning and transcribing books, newspapers and images, 3d-scanning artworks or digitizing music has opened up this heritage for example for digital humanities research or even for creative computing. However, with respect to the performing arts, including theater and more specifically dance, digitization is a serious research challenge. Several dance notation schemes exist, with the most established one being Labanotation, developed in 1920 by Rudolf von Laban. Labanotation uses a vertical staff notation to record human movement in time with various symbols for limbs, head movement, types and directions of movements.

Generated variations of movements used for training the recognizers

Where for musical scores, good translations to digital formats exist (e.g. MIDI), for Lanabotation, these are lacking. While there are structured formats (LabanXML, MovementXML), the majority of content still only exists either in non-digitized form (on paper) or in scanned images. The research challenge of Michelle de Böck’s thesis therefore was to identify design features for a system capable of recognizing Labanotation from scanned images.

Examples of Labanotation files used in the evaluation of the system.

Michelle designed such a system and implemented this in MATLAB, focusing on a few movement symbols. Several approaches were developed and compared, including approaches using pre-trained neural networks for image recognition (AlexNet). This approach outperformed others, resulting in a classification accuracy of 78.4%. While we are still far from developing a full-fledged OCR system for Labanotation, this exploration has provided valuable insights into the feasibility and requirements of such a tool.

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The ESWC2019 PhD Symposium

As part of the ESWC 2019 conference program, the ESWC PhD Symposium was held in wonderful Portoroz, Slovenia. The aim of the symposium, this year organized by Maria-Esther Vidal and myself, is to provide a forum for PhD students in the area of Semantic Web to present their work and discuss their projects with peers and mentors.

Even though this year, we received 5 submissions, all of the submissions were of high quality, so the full day symposium featured five talks by both early and middle/late stage PhD students. The draft papers can be found on the symposium web page and our opening slides can be found here. Students were mentored by amazing mentors to improve their papers and presentation slides. A big thank you to those mentors: Paul Groth, Rudi Studer, Maria Maleshkova, Philippe Cudre-Mauroux,  and Andrea Giovanni Nuzzolese.

The program also featured a keynote by Stefan Schlobach, who talked about the road to a PhD “and back again”. He discussed a) setting realistic goals, b) finding your path towards those goals and c) being a responsible scientist and person after the goal is reached.

Students also presented their work through a poster session and the posters will also be found at the main conference poster session on tuesday 4 June.

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6th International Symposium “Perspectives on ICT4D”

On 23 May, as part of the VU ICT4D course, for the 6th time, W4RA and SIKS organized the annual symposium “Perspectives on ICT4D“. This year’s theme was how to tackle “Global Challenges” in a collaborative, trans-disciplinary way. Food Security is one of the Global Challenges Lia van Wesenbeeck – Director of the Amsterdam Centre for World Food Studies – gave a great presentation on “Tackling World Food Challenges”.

Our international speaker on the same topic, Mr. Seydou Tangara, coordinator of the AOPP, was unfortunately not able to join due to visa problems. He was replaced by prof. Hans Akkermans, who presented the Vienna manifesto on digital humanism and its relation to ICT4D.

Andre Baart from UvA talked about the CARPA project and challenges in developing applications for people in Mali while Jaap Gordijn discussed the need for business modelling for developing sustainable services, with interesting case studies from Sarawak, Malaysia.

The ICT4D students presented their voice application services during the coffee break. They demonstrated applications ranging from equipment-lending services to seed markets and weather services.

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Digital Humanities in Practice 2018/2019

Last friday, the students of the class of 2018/2019 of the course Digital Humanities and Social Analytics in Practice presented the results of their capstone internship project. This course and project is the final element of the Digital Humanities and Social Analytics minor programme in which students from very different backgrounds gain skills and knowledge about the interdisciplinary topic.

Poster presentation of the DHiP projects

The course took the form of a 4-week internship at an organization working with humanities or social science data and challenges and student groups were asked to use these skills and knowledge to address a research challenge. Projects ranged from cleaning, indexing, visualizing and analyzing humanities data sets to searching for bias in news coverage of political topics. The students showed their competences not only in their research work but also in communicating this research through great posters.

The complete list of student projects and collaborating institutions is below:

  • “An eventful 80 years’ war” at Rijksmuseum identifying and mapping historical events from various sources.
  • An investigation into the use of structured vocabularies also at the Rijksmuseum
  • “Collecting and Modelling Event WW2 from Wikipedia and Wikidata” in collaboration with Netwerk Oorlogsbronnen (see poster image below)
  • A project where an search index for Development documents governed by the NICC foundation was built.
  • “EviDENce: Ego Documents Events modelliNg – how individuals recall mass violence” – in collaboration with KNAW Humanities Cluster (HUC)
  • “Historical Ecology” – where students searched for mentions of animals in historical newspapers – also with KNAW-HUC
  • Project MIGRANT: Mobilities and connection project in collaboration with KNAW-HUC and Huygens ING
  • Capturing Bias with media data analysis – an internal project at VU looking at indentifying media bias
  • Locating the CTA Archive Amsterdam where a geolocation service and search tool was built
  • Linking Knowledge Graphs of Symbolic Music with the Web – also an internal project at VU working with Albert Merono
One of the posters visualizing the events and persons related to the occupation of the Netherlands in WW2
Update: The student posters are now online at https://github.com/biktorrr/dhip2019posters

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Architectural Digital Humanities student projects

In the context of our ArchiMediaL project on Digital Architectural History, a number of student projects explored opportunities and challenges around enriching the colonialarchitecture.eu dataset. This dataset lists buildings and sites in countries outside of Europe that at the time were ruled by Europeans (1850-1970).

Patrick Brouwer wrote his IMM bachelor thesis “Crowdsourcing architectural knowledge: Experts versus non-experts” about the differences in annotation styles between architecture historical experts  and non-expert crowd annotators. The data suggests that although crowdsourcing is a viable option for annotating this type of content. Also, expert annotations were of a higher quality than those of non-experts. The image below shows a screenshot of the user study survey.

Rouel de Romas also looked at crowdsourcing , but focused more on the user interaction and the interface involved in crowdsourcing. In his thesis “Enriching the metadata of European colonial maps with crowdsourcing”  he -like Patrick- used the Accurator platform, developed by Chris Dijkshoorn. A screenshot is seen below.  The results corroborate the previous study that the in most cases the annotations provided by the participants do meet the requirements provided by the architectural historian; thus, crowdsourcing is an effective method to enrich the metadata of European colonial maps.

Finally, Gossa Lo looked at automatic enrichment using OCR techniques on textual documents for her Mini-Master projcet. She created a specific pipeline for this, which can be seen in the image below. Her code and paper are available on this Github page:https://github.com/biktorrr/aml_colonialnlp

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Who uses DBPedia anyway?

[this post is based on Frank Walraven‘s Master thesis]

Who uses DBPedia anyway? This was the question that started a research project for Frank Walraven. This question came up during one of the meetings of the Dutch DBPedia chapter, of which VUA is a member. If usage and users are better understood, this can lead to better servicing of those users, by for example prioritizing the enrichment or improvement of specific sections of DBPedia Characterizing use(r)s of a Linked Open Data set is an inherently challenging task as in an open Web world, it is difficult to know who are accessing your digital resources. For his Msc project research, which he conducted at the Dutch National Library supervised by Enno Meijers , Frank used a hybrid approach using both a data-driven method based on user log analysis and a short survey of know users of the dataset. As a scope Frank selected just the Dutch DBPedia dataset.

For the data-driven part of the method, Frank used a complete user log of HTTP requests on the Dutch DBPedia. This log file (see link below) consisted of over 4.5 Million entries and logged both URI lookups and SPARQL endpoint requests. For this research only a subset of the URI lookups were concerned.

As a first analysis step, the requests’ origins IPs were categorized. Five classes can be identified (A-E), with the vast majority of IP addresses being in class “A”: Very large networks and bots. Most of the IP addresses in these lists could be traced back to search engine

indexing bots such as those from Yahoo or Google. In classes B-F, Frank manually traced the top 30 most encounterd IP-addresses, concluding that even there 60% of the requests came from bots, 10% definitely not from bots, with 30% remaining unclear.

The second analysis step in the data-driven method consisted of identifying what types of pages were most requested. To cluster the thousands of DBPedia URI request, Frank retriev

ed the ‘categories’ of the pages. These categories are extracted from Wikipedia category links. An example is the “Android_TV” resource, which has two categories: “Google” and “Android_(operating_system)”. Following skos:broader links, a ‘level 2 category’ could also be found to aggregate to an even higher level of abstraction. As not all resources have such categories, this does not give a complete image, but it does provide some ideas on the most popular categories of items requested. After normalizing for categories with large amounts of incoming links, for example the category “non-endangered animal”, the most popular categories where 1. Domestic & International movies, 2. Music, 3. Sports, 4. Dutch & International municipality information and 5. Books.

Frank also set up a user survey to corroborate this evidence. The survey contained questions about the how and why of the respondents Dutch DBPedia use, including the categories they were most interested in. The survey was distributed using the Dutch DBPedia websitea and via twitter however only attracted 5 respondents. This illustrates

the difficulty of the problem that users of the DBPedia resource are not necessarily easily reachable through communication channels. The five respondents were all quite closely related to the chapter but the results were interesting nonetheless. Most of the users used the DBPedia SPARQL endpoint. The full results of the survey can be found through Frank’s thesis, but in terms of corroboration the survey revealed that four out of the five categories found in the data-driven method were also identified in the top five resulting from the survey. The fifth one identified in the survey was ‘geography’, which could be matched to the fifth from the data-driven method.Frank’s research shows that although it remains a challenging problem, using a combination of data-driven and user-driven methods, it is indeed possible to get an indication into the most-used categories on DBPedia. Within the Dutch DBPedia Chapter, we are currently considering follow-up research questions based on Frank’s research.

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