ESWC2024 Trip report

Last week, I joined the 21st edition of the Extended Semantic Web Conference (ESWC2024) held in Heraklion Crete. The 2004 edition was my first scientific conference ever, and I have been going to many editions ever since, so this feels a bit like my ‘home conference’. General Chair Albert Meroño and his team did a great job and it was overall a very nice conference. Paul Groth wrote a very nice trip report here, but I wanted to collect some thoughts and personal highlights in a short blogpost anyway.

The workshops

The workshops overall were very well organized and the ones I joined were well attended. This has been different in previous editions! The PhD symposium was very lively and I had nice chats with PhD candidates during the symposium lunch.

I joined part of the Genesy Workshop, where there were various talks about the potential of generative AI (a definite and unsurprising theme of the conference) and Semantic Web processes and technologies. The paper from Bouchouras et al: LLMs for the Engineering of a Parkinson Disease Monitoring and Alerting Ontology looked at using LLMs for Knowledge Engineering.

I was asked to give a keynote speech at the 2nd edition of the Workshop on Semantic Methods for Events and Stories (SEMMES), at ESWC2024. I talked about work on polyvocality in cultural heritage knowledge graphs. You can find my slides here.

There were very nice talks in the workshop, including the (best paper winning) Let the fallen voussoirs of Notre-Dame de Paris speak: Scientific Narration and 3D Visualization of Virtual Reconstruction Hypotheses and Reasoningfrom Guillem Anais, John Samuel, Gilles Gesquière, Livio De Luca and Violette Abergel that looked at a combination of modelling, argumentation and visualisation for architectural reconstruction.

I then joined the SemDH workshop on Semantic Digital Humanities and its panel discussion in the afternoon, which was really nice. One observation is that many of the talks in SEMMES could have been very interesting for SemDH as well and vice versa. Maybe merging the two would make sense in the future?

The Keynotes

There were three nice keynote speeches, each with its own angle and interesting points.

Elena Simperl gave a somewhat personal history of Knowledge Engineering and the role that machines and humans have in this process. This served as a prelude for the special track on this topic organized by her, Paul Groth and others. Elena called for tools and data for proper benchmarking, introduced the ProVe tool for provenance verification and explored what the roles are of AI (LLM) with respect to Knowledge engineers, domain experts and prompt engineers.

Katariina Kari reflected on 7 Years of Building Enterprise Knowledge Graphs at Zalando and Ikea. This was a very interesting talk about the impact of Knowledge Graphs in industry (she mentioned 7 figure sales increases) and about what works (SKOS, SHACL, OntoClean, Reasoning) and what doesnt work or isnt needed (OWL, Top level ontologies, big data).

Peter Clark of the Allen Institute for AI gave my favorite talk on Structured Reasoning with Language. He discussed their research on Knowledge Graphs and reasoning but also on Belief Graphs, that consist of atomic statements with textual entailment relations. LLMs can be used to ‘reason’ over such Belief Graphs for for example explaining decisions or search results.

Main Conference

The main conference had many interesting talks in all the tracks. The industry track and resource track were quite competitive this year. In terms of quality and number of submissions, they seemed equal to the research track to me this year. Also, the special track on LLMs for Knowledge Engineering was a great success.

I was a bit hesitant with respect to this clear theme of the conference, fearing lots of “we did LLM” talks, but that was not the case at all. Most papers showed genuine interest in the strength and weaknesses of various LLMs and how they can be used in several Semantic web tasks and pipelines. There was clearly a renewed interest in methodologies (Neon, Ontology Engineering 101, Methontology etc ) and how LLMs can fit here. There were for example several talks on how LLMS can be used to generate competency questions: (“Can LLMs Generate Competency Questions? [pdf] by Youssra Rebboud et al. and “The Role of Generative AI in Competency Question Retrofitting” [pdf] by Reham Alharbi et al.”).

Roderick presenting our Resource paper

Roderick van der Weerdt presented our -best Resource paper nominated- OfficeGraph: A Knowledge Graph of Office Building IoT Measurements [pdf]. Roderick did a great job presenting this nice result from the InterConnect project and it was well-received. The winner of the Resource track best paper award was however “PyGraft: Configurable Generation of Synthetic Schemas and Knowledge Graphs at Your Fingertips [pdf] by Nicolas Hubert et al (in my view deservedly so).

The in-use track also had very nice papers, including a quite holistic system to map the German Financial system with knowledge Graphs [pdf] by Markus Schröder et al. Oh, and I won an award 🙂

With more focus on applications, in use, resources, methods for knowledge engineering and of course LLMs, some topics seem to get less attention. Ironically, I missed both Semantics and the Web: Semantics and reasoning did not get a lot of attention in the talks I attended and most applications were about singular knowledge graphs, rather than distributed datasets. Maybe this means that we have solved most of the challenges around these two topics, but possibly it also means that these two elements are less important for actual implementation of Knowledge Graphs. It makes one wonder about the name of the conference though…

With a truly great demo and poster session (near the beach), a great dinner, really nice people and the wonderful surroundings, ESWC2024 was a great success. See you next year in Portoroz!?

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A Polyvocal and Contextualised Semantic Web

[This post is the text of a 1-minute pitch at the IWDS symposium for our poster “A Polyvocal and Contextualised Semantic Web” which was published as the paper”Erp, Marieke van, and Victor de Boer. “A Polyvocal and Contextualised Semantic Web.” European Semantic Web Conference. Springer, Cham, 2021.”]

Knowledge graphs are a popular way of representing and sharing data, information and knowledge in many domains on the Semantic Web. These knowledge graphs however often represent singular -biased- views on the word, this can lead to unwanted bias in AI using this data. We therefore identify a need a more polyvocal Semantic Web.

So. How do we get there?

  1. We need perspective-aware methods for identifying existing polyvocality in datasets and for acquiring it from text or users.
  2. We need datamodels and patterns to represent polyvocal data information and knowledge.
  3. We need visualisations and tools to make the polyvocal knowledge accessible and usable for a wide variety of users, including domain experts or laypersons with varying backgrounds.

In the Cultural AI Lab, we investigate these challenges in several interrelated research projects, but we cannot do it, and should not do it alone and are looking for more voices to join us!

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Hearing (Knowledge) Graphs

[This post is based on Enya Nieland‘s Msc Thesis “Generating Earcons from Knowledge Graphs” ]

Three earcons with varying pitch, rythm and both pitch and rythm

Knowledge Graphs are becoming enormously popular, which means that users interacting with such complex networks are diversifying. This requires new and innovative ways of interacting. Several methods for visualizing, summarizing or exploring knowledge have been proposed and developed. In this student project we investigated the potential for interacting with knowledge graphs through a different modality: sound.

The research focused on the question how to generate meaningful sound or music from (knowledge) graphs. The generated sounds should provide users some insights into the properties of the network. Enya framed this challenge with the idea of “earcons” the auditory version of an icon.

Enya eventually developed a method that automatically produces these types of earcon for random knowledge graphs. Each earcon consist of three notes that differ in pitch and duration. As example, listen to the three earcons which are shown in the figure on the left.

Earcon where pitch varies
Earcon where note duration varies
Earcon where both pitch and rythm vary

The earcon parameters are derived from network metrics such as minimum, maximum and average indegree or outdegree. A tool with user interface allowed users to design the earcons based on these metrics.

The pipeline for creating earcons

The different variants were evaluated in an extensive user test of 30 respondents to find out which variants were the most informative. The results show that indeed, the individual elements of earcons can provide insights into these metrics, but that combining them is confusing to the listener. In this case, simpler is better.

Using this tool could be an addition to a tool such as LOD Laundromat to provide an instant insight into the complexity of KGs. It could additionally benefit people who are visually impaired and want to get an insight into the complexity of Knowledge Graphs

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Msc project: Low-Bandwith Semantic Web

[This post is based on the Information Sciences MSc. thesis by Onno Valkering]

To make widespread knowledge sharing possible in rural areas in developing countries, the notion of the Web has to be downscaled based on the specific low-resource infrastructure in place. In this paper, we introduce SPARQL over SMS, a solution for exchanging RDF data in which HTTP is substituted by SMS to enable Web-like exchange of data over cellular networks.

SPARQL in an SMS architecture
SPARQL over SMS architecture

The solution uses converters that take outgoing SPARQL queries sent over HTTP and convert them into SMS messages sent to phone numbers (see architecture image). On the receiver-side, the messages are converted back to standard SPARQL requests.

The converters use various data compression strategies to ensure optimal use of the SMS bandwidth. These include both zip-based compression and the removal of redundant data through the use of common background vocabularies. The thesis presents the design and implementation of the solution, along with evaluations of the different data compression methods.

Test setup with two Kasadakas
Test setup with two Kasadakas

The application is validated in two real-world ICT for Development (ICT4D) cases that both use the Kasadaka platform: 1) An extension of the DigiVet application allows sending information related to veterinary symptoms and diagnoses accross different distributed systems. 2) An extension of the RadioMarche application involves the retrieval and adding of current offerings in the market information system, including the phone number of the advertisers.

For more information:

  • Download Onno’s Thesis. A version of the thesis is currently under review.
  • The slides for Onno’s presentation are also available: Onno Valkering
  • View the application code at


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DownScale 2013 workshop

DOWNSCALE 2013, the 2nd international workshop on downscaling the Semantic Web was held on 19-9-2013 in Geneva, Switzerland and was co-located with the Open Knowledge Conference 2013. The workshop seeks to provide first steps in exploring appropriate requirements, technologies, processes and applications for the deployment of Semantic Web technologies in constrained scenarios, taking into consideration local contexts. For instance, making Semantic Web platforms usable under limited computing power and limited access to Internet, with context-specific interfaces.

Downscale group picture
Downscale group picture

The workshop accepted three full papers after peer-review and featured five invited abstracts. in his keynote speech, Stephane Boyera of SBC4D gave a very nice overview of the potential use of Semantic Web for Social & Economic Development. The accepted papers and abstracts can be found in the  downscale2013 proceedings, which will also appear as part of the OKCon 2013 Open Book.


We broadcast the whole workshop live on the web, and you can actually watch the whole thing (or fragments) via the embedded videos below.

After the presentations, we had fruitful discussions about the main aspects of ‘downscaling’. The consensus seemed to be that Downscaling involved the investigation and usage of Semantic Web technologies and Linked Data principles to allow for data, information and knowledge sharing in circumstances where ‘mainstream’ SW and LD is not feasible or simply does not work. These circumstances can be because of cultural, technical or physical limitations or because of natural or artificial limitations.


The figure  illustrates a first attempt to come to a common architecture. It includes three aspects that need to be considered when thinking about data sharing in exceptional circumstances:

  1. Hardware/ Infrastructure. This aspect includes issues with connectivity, low resource hardware, unavailability, etc.
  2.  Interfaces. This concerns the design and development of appropriate interfaces with respect to illiteracy of users or their specific usage. Building human-usable interfaces is a more general issue for Linked data.
  3. Pragmatic semantics. Developing LD solutions that consider which information is relevant in which (cultural) circumstances is crucial to its success. This might include filtering of information etc.

The right side of the picture illustrates the downscaling stack.

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