Abstract
This is the second volume of the Special Issue celebrating 10 years of the Joint Ontology Workshops (JOWO). As in the first volume, the second volume includes extended versions of selected papers that were originally presented at JOWO workshops. In this editorial, we moreover offer a retrospective view of the history of the venue, an overview of the variety of topics it has hosted, and an analysis of their evolution over time, reflecting on the development of the community and the diversity of research it has fostered. Together, these elements provide a picture of JOWO as a space where foundational concerns coexist with a broad and expanding range of more applied ontology-related research themes. The papers collected in the two volumes of the Special Issue illustrate both the continuity of core topics and a growing openness towards application-oriented work, as well as the exploratory role of JOWO as a venue for emerging ideas. This editorial thus introduces and situates the contributions in this volume within the broader trajectory of the JOWO community.
Introduction
The Joint Ontology Workshops (JOWO) is the flagship venue of the International Association for Ontology and its Applications (IAOA), bringing together workshops that connect the communities of formal and applied ontology with intersecting communities in other fields of knowledge. Since its inception in 2015, JOWO has been held annually, regularly co-locating with the International Conference on Formal Ontology in Information Systems (FOIS). This sounds like a simple and linear story, but the reality was rather different, and we use the opportunity of this editorial to record some elements of JOWO’s history. To celebrate the 10th edition of the JOWO series, which was organised in 2024, this special edition of the Applied Ontology journal has been organised, welcoming extended versions of papers originally published at JOWO workshops, and with the aim of showcasing the evolution of high-quality works that originated in this venue. This editorial serves as the preface to the second and final volume of this special issue.
In the editorial to the first volume, we already sketched and discussed the motivations and organisation of this special issue project, see Righetti et al. (2025). Here, we want to record a little bit of history and genesis of the JOWO series itself, and look at the topics and trends over a decade of research in applied ontology. We close with a brief outline of the papers included in this volume and an outlook to the next decade of JOWO.
The Joint Ontology Workshops: A Bit of History
A New Hope: 2015–16
Some time in early 2015, a number of workshop organisers of IJCAI 2015 workshops, events that had in common that they touched on applied ontology, and perhaps in different ways, started conspiring to organise something they first called ‘federated ontology workshops’. The organisers of this first event were (in the order as listed on the workshops’ website) Stefano Borgo, Oliver Kutz, and Daniele Porello (for ‘Formal Ontologies for Artificial Intelligence ’), Kenneth Baclawski, Torsten Hahmann, Pavel Klinov, Adila Krisnadhi (for ‘9th Workshop on Modular Ontologies’), Eduardo Fermé, Thomas Meyer and Renata Wassermann (for ‘1st Workshop on Belief Change and Non-Monotonic Reasoning in Ontologies and Databases’), and Odile Papini, Marie-Laure Mugnier, Laurent Garcia, Salem Benferhat (for ‘Ontologies and logic programming for query answering’). From the start, some of the advantages of coordinating were obvious: shared publicity, shared proceedings, and community exchange. In particular, the support of the CEUR Workshop Proceedings was a key asset from the very beginning, giving the JOWO community a free diamond open access publisher that, crucially, was open to the joint proceedings format. As an important side-effect and motivator, this allowed the inclusion of shorter, more specialised workshops that would typically be organised in a half-day programme. Although the IAOA subseries at CEUR was only founded in 2018, all the JOWO proceedings since 2015 can now be found in this series. 1
On January 16th 2015, Oliver Kutz suggested to ‘hype this a little bit’ by calling it the ‘Argentinian Summer of Ontology’. 2 It was Torsten Hahmann who quickly pointed out, on the same day, that July in Argentina was in fact not Summer but Winter, and it was Ken Baclawski who pointed out that ‘Argentinian’ was perhaps bad English. A few days later, on the 19th of January, all core elements of the event would be decided and summarised, the name of the event was fixed and the first draft of the Call for Papers was about to be distributed:
The Joint Ontology Workshops (JOWO).JOWO 2015 Episode I: The Argentine Winter.
As can be sensed from the naming schema, this choice was both playful and confident. It was playful using a Star Wars metaphor to underline that something new with somewhat novel rules was born, and it was confident by suggesting that after Episode I, there must surely be an Episode II! Sure enough, it arrived in 2016.
JOWO 2016: Episode II: The French Summer
From the first edition on, JOWO was endorsed and supported also financially as an event of the International Association for Ontology and its Applications, IAOA. After the success of the first year, it was an obvious idea to collocate with the flagship conference of the IAOA, namely the FOIS conference ‘Formal Ontology in Information Systems’ held in Annecy (France) in 2016. In that year, the JOWO workshops comprised four events, but they also replaced the usual FOIS workshop. This started a debate about the status of the JOWO event that only got resolved several years later.
JOWO Awakens: 2017–19
Note that in 2017 and also in 2019, there was no FOIS conference being organised since FOIS was still a biannual conference. This only changed in 2023 at which point FOIS turned into a yearly event. 2017 can therefore be considered from many perspectives as the year in which JOWO’s potential was for the first time fully realised.
JOWO 2017: Episode III: The Tyrolean Autumn JOWO 2018: Episode IV: The South African Spring JOWO 2019: Episode V: The Styrian Autumn of Ontology
In Episode III, JOWO 2017, organised at the Free University of Bozen-Bolzano in Italy, was for the first time organised as an independent event, running over 3 days, with a total of 10 workshops in an integrated program including shared keynotes by Alessandro Mosca, Antonio Chella, Giancarlo Guizzardi, and Todd Oakley, as well as a concert by the Hyperinstruments Ensemble of the music conservatory of Bolzano ’Claudio Monteverdi’ led by Nicola Baroni. It established a number of aspects that later editions of JOWO would tend to repeat: parallel sessions, joined keynotes, and engaging social events that would bring together the different workshop communities. JOWO 2017 had over 100 participants. Whilst in 2018, we saw JOWO going back to a more traditional format hosting the satellite workshops and tutorials of FOIS in Cape Town, the 2019 edition in Graz, Episode V, followed closely the format of the 2017 edition as a free standing event, this time with 12 workshops and 5 tutorials, the biggest to date.
The Revenge of the Virus: 2020–2021
At the peak of its early development, JOWO, like any other scientific event at the time, was hit by the lockdowns of 2020 and 2021.
JOWO 2020: Episode VI: The Bolzano Summer of Knowledge JOWO 2021: Episode VII: The Bolzano Summer of Knowledge
Indeed, the JOWO 2020 edition had been planned as a participant in the Bolzano Summer of Knowledge (BOSK)
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, a massive collocation of knowledge-focussed conferences and workshops, that eventually was held entirely online in 2020. However, a large number of the events was held again in hybrid mode in 2021.
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The story of those years is consequently a little complicated. In 2020, JOWO had 16 workshops and 4 tutorials affiliated with the conferences EKAW, FOIS, and ICBO. In 2021, Episode VII brought together workshops and tutorials as part of BOSK 2.0, namely affiliated with FOIS 2021, the 12th International Conference on Formal Ontology in Information Systems, and ICBO 2021, the 12th International Conference on Biomedical Ontologies. The proceedings also included the ‘Early Career Symposium’, ‘Ontology Showcase’, and ‘Demonstrations’ of FOIS. Although these were still successful events, they could not repeat the well-integrated and highly communicative flavour of the previous three JOWO editions.
The Rise of JOWO: 2022–2026
On many levels, the first post-pandemic event, Episode VIII: The Svear Sommar of Ontology, was a huge success and got JOWO back on track.
JOWO 2022: Episode VIII: The Svear Sommar of Ontology
Organised by Maria M. Hedblom and Tan He at Jönköping University (Sweden), it reminded everybody why the JOWO events had been such a big success before. Running as an independent event over 5 days, with 8 workshops and 3 tutorials, keynotes by Peter Gärdenfors, Sebastian Rudolph, and Janna Hastings, a panel debate on the ‘Foustian Struggle’
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and featuring both a visit to a candy factory and a barbecue at the beach, it set a new standard what a JOWO event should aim for.
However, after the IAOA assembly and Executive Council decided to run FOIS as a yearly conference beginning in 2023, things had to change. As organising both an independent JOWO and a major conference yearly seemed too difficult to handle in the long run, the agreement reached was the following: JOWO is considered an independent event with its own Program Chairs and Organisers (rather than a satellite of FOIS), however it will (typically) collocate with FOIS and the ISAO International Summer School of Applied Ontology, thus maximising community impact whilst keeping it manageable as an event. Today, JOWO has been fully adopted by the IAOA, and the steering committee of JOWO coincides with the Executive Council of the IAOA.
JOWO 2023: Episode IX: The Quebec Summer of Ontology JOWO 2024: Episode X: The Tukker Zomer of Ontology JOWO 2025: Episode XI: The Sicilian Summer under the Etna JOWO 2026: Episode XII: The Tropical Spring of Ontology
The Episodes IX–XI held in Sherbrooke (Canada), Twente (The Netherlands), and Catania (Italy) all followed this model, as will Episode XII to be held in 2026 in Vitória (Brazil). In total, these 3 Episodes hosted 36 workshops (and some FOIS sub-events) and a total of 219 papers were published overall in the joint proceedings, illustrating the impressive growth and stability of the newly formed community that is the Joint Ontology Workshops.
Workshops’ Breadth in a Decade of JOWO
As the history makes clear, the emerging goal of JOWO was to bring together the multifaceted world of the applied ontology community within a single event. Organised as a blend of different workshops, the event by design aims to collect a miscellany of topics, from foundational issues, to ontology applications spanning across different domains. Although this tendency was there since the very beginning of JOWO, it has become more and more evident as time passes and the event grows.
If we study the evolution of JOWO quantitatively, the data shows that JOWO has grown quite substantially over time. In its early editions (2015–2016), the event was relatively small, with only a handful of workshops and a limited number of papers. From 2017 onwards, the number of papers and workshops increase noticeably. As shown in Figure 1(a), the number of workshops expands in steps rather than steadily, but the overall trajectory is clearly upward. This suggests a gradual consolidation of the event alongside an expansion of its thematic scope. Perhaps not surprisingly, a similar pattern can be observed in the number of papers. Figure 1(b) highlights this dynamic: peaks in 2019 and 2024 correspond to moments of particularly high activity, whereas lower years appear as temporary dips rather than structural declines.
(a) On the left we see the number of JOWO workshops organised per year, whilst (b) shows the number of accepted and published papers per year. (a) Number of workshops per year and (b) Number of papers per year.
In total, 37 different workshops were organised during the ten years of JOWO (spanning from 2015 to 2024). One of the more notable aspects of the data is the presence of recurring workshops. Out of these 37 workshops, 18 workshops decided to organise at least a second edition of their workshop at JOWO, see Table 1. Interestingly, seven new workshops were organised in the last edition in our dataset (JOWO 2024), demonstrating a lively and open community. If we exclude newcomers from the count, almost two-thirds of the workshops participated more than once over the ten years.
Recurring Workshops at JOWO and Their Number of Occurrences Over the 10 Years.
A number of workshops – such as CAOS, FOUST, FOMI, etc. – reappear regularly across different editions. These can be understood as relatively stable sub-communities within JOWO. Their regular presence suggests that they have established a clear identity, a consistent audience, and a set of ongoing research questions. In this sense, they provide continuity across editions and contribute to shaping the overall profile of JOWO.
At the same time, there is a large set of workshops that appear only once. These one-off events point to a more exploratory side of JOWO, where new ideas, emerging topics, or smaller communities can find a space. Not all of these develop into recurring workshops, but they still play an important role in keeping the event open and adaptable. Moreover, they contribute to the diversity of topics covered by JOWO, which can be appreciated in Figure 2. 6 More prominent terms such as ‘Cognition’ and ‘Foundational issues’ appear larger, highlighting their central role, while a wide range of smaller terms reflects the thematic breadth of JOWO.
The image provides a word cloud representation of keyword frequencies. The keywords were selected by the authors based on workshop names and topics (e.g. cognition for CAOS). The frequency is given by the repetition of keywords across workshops (e.g. cognition for CAOS and SHAPES), and repetitions of workshops over the years (twice for SHAPES, seven times for CAOS).
The previous section gives us an idea of the variety of JOWO’s topics, but it does not tell us much about how these topics evolved over the past ten years.
Considering the word cloud (Figure 2) and the table listing the most recurring workshops (Table 1), the foundational nature of the core topics of JOWO is apparent. Both FOUST and CAOS, the most stable pillars of the event, are arguably interested in essential questions about the ontology and representation of reality and cognition. Complementing this core, a number of different domains (robotics, legal domain, social domain, etc) appear almost every year across different workshops.
More specifically, JOWO’s identity can be structured along two orthogonal dimensions, spanning from formal theories to applications on the one hand, and from foundational issues to domain modelling on the other (Figure 3).
JOWO’s identity structured along two orthogonal dimensions: from formal theories to applications, and from foundational issues to domain modelling.
An important question is how the different dimensions of JOWO have evolved over the past decade, whether some have grown more prominently than others, and what this may reveal about the future trajectory of JOWO.
To give some partial answers to this question, we conducted a corpus-based lexical frequency analysis to generate and analyse word lists based on the papers published over the 10 years of JOWO. Specifically, for each volume of the proceedings, we constructed a corpus by submitting the corresponding URL to the corpus analysis platform Sketch Engine. The corpora were generated automatically, after which word lists were extracted, excluding single letters and non-lexical items. 7
Afterwards, we selected some keywords to characterise the four clusters in Figure 3, and checked how the frequency of such keywords has evolved over the years. For the cluster formal modelling we identified the keywords logic, axiom, set, reasoning and semantics; as representative for applications, we selected instead kg/graph, data, interoperability, AI, information. Foundational ontology was represented by mereology/whole, process, event, function, role, and Domain ontology by legal/law, food, social/society, robot/robotics and bioinformatics/snomed.
The keywords were selected by the authors as plausible representatives of the respective clusters, based on their relevance to the underlying themes. The analysis is thus intended as an exploratory one, aimed at supporting discussion rather than providing a rigorous quantitative assessment, and should be understood primarily in a qualitative sense. Figure 4 shows the result.
Evolution of the frequency of the selected keywords over the 10 years of JOWO.
The four clusters exhibit different dynamics. The foundational ontology shows relatively stable activity over time, with peaks in 2019–2020, but otherwise with a continued and sustained presence thereafter. Foundational issues persist in time, even as other areas evolve.
Domain ontology, as may be expected, shows a more irregular pattern. Individual topics (e.g. robotics, food, legal, etc.) fluctate over time, reflecting the presence or absence of the corresponding workshops in each annual edition of JOWO. This cluster once more highlights the pluralistic nature of domain-specific applications.
The other dimension offers a different perspective. Formal modelling appears more prominent in the early years, with a peak in frequency for terms like logic, set, axioms around 2015–2017, followed by a gradual decline. This pattern may indicate an initial strong focus on formal aspects of ontology that become less prominent over time.
The application cluster shows a different trajectory, with a clear increase in recent years. Terms such as knowledge graph, data and interoperability grow, especially from 2020, pointing to a shift towards more data-oriented research.
Taken together, these trends suggest a slow shift from an early focus on formal modelling towards a more application-driven and diversified landscape, while foundational ontology provides a stable conceptual backbone.
To complement this analysis, we also experimented with an automated keyword clustering approach based on semantic embeddings and K-means clustering. 8 This method provides a more systematic and quantitative approach. However, the resulting keywords did not always yield precise or meaningful characterisations of the clusters. We only include here the comparison with FOIS based on this approach (see Figure 5), as it offers an additional interesting cue for contrasting the two venues.
Radar chart comparing the thematic profiles of JOWO and FOIS.
The figure presents a radar chart comparing the thematic profiles of JOWO and FOIS across five macro-clusters derived from the keyword analysis: Knowledge Graphs & AI, Ontology Engineering, Formal Ontology Concepts, Mereology & Cognition, and Conceptual Modelling. Values are expressed as percentage shares, indicating the relative weight of each theme in the two venues.
We do not attempt a detailed comparison of the thematic profiles, as the automatically derived keywords may not provide sufficiently reliable characterisation of the clusters. Instead, we focus on a clearer pattern: the stronger orientation towards application-driven topics in JOWO compared to FOIS. 9 Since these areas largely correspond to emerging themes, this supports the unsurprising view that JOWO serves as a venue where new topics and research themes are more actively experimented with.
Three papers compose the second and final volume of this JOWO anniversary special issue. Demonstrating the foundational core of JOWO, they are all extensions of papers originally published within the Foundational Ontology Workshop (FOUST).
We start with the extension of Gnatenko et al. (2024). This paper was the inaugural winner of the Best of JOWO Award implemented in 2024. This award recognises the excellence of the research produced in the JOWO community. It is awarded by first collecting nominations for best papers from individual workshops, and then selecting a winner from those shortlisted papers through a committee including the JOWO PC and General Chairs. In their paper, Gnatenko, Kutz and Troquard develop the principles of an ontologically well-founded knowledge base of computational complexity, ‘Ontoplex’ – (onto)logy of com(plex)ity. The research aims to enable storing, querying, and reasoning over algorithmic problems, complexity classes, and other features in the theory of computational complexity. It is designed both to represent existing knowledge on the topic as can be found e.g. in Scott Aaronson’s ‘Complexity Zoo’, and to facilitate the discovery of new results through automated reasoning techniques.
The second paper of the volume is the evolution of Toyoshima et al. (2024). In the paper, Toyoshima, Barton, Koslicki and Massin propose a novel perspective on the ontology of artefacts, shifting the focus from traditional function-based accounts to a framework centred on the notion of realisable entity. The approach thus places particular emphasis on the intentional dimension of artefacts, allowing for a unified treatment of a wide range of use cases, from technical artefacts to artworks. Specifically, by introducing the distinction between canonical artefacts and usefacts, the authors offer the conceptual toolkit for analysing how artefacts relate to purposes and uses. To make the proposal concrete, the paper also discusses how this perspective can be aligned with established foundational ontologies such as the Basic Formal Ontology (BFO). This line of work also informed subsequent research on malfunctioning artefacts, namely Toyoshima and Jansen (2025), presented at FOUST a year later and which received the Best of JOWO 2025 Award.
The third paper in the volume extends the work Burek et al. (2020). In this paper, Burek, Loebe, Schäfermeier, Scherf, Uciteli, Kondracki and Herre address the challenging problem of modelling situations in ontology engineering, drawing on experience from different biomedical applications. Building on the General Formal Ontology (GFO), the paper proposes a systematic and flexible set of ontology design patterns for representing situations at different granularity. Specifically, rather than advocating for a single modelling solution, the authors develop a family of interrelated patterns that can be adapted to a wide range of use cases, allowing modellers to move between more high-level and more detailed representations as needed.
To summarise, this Special Issue for the anniversary of JOWO comprises two volumes for a total of eight papers. Six of these are extended versions of contributions previously presented at the Foundational Ontology workshop (FOUST); one derives from the Cognition and Ontologies workshop (CAOS); and one from the Semantic Shields workshop. As a result, the overall thematic orientation of the volume may be expected to lean towards foundational issues.
Despite this, a closer look at the keywords associated with these papers reveals a different story and reflects once more the multifaceted nature of JOWO. Figure 6 presents a manual classification of such keywords along the two dimensions introduced above (formal theories vs applications and foundational vs domain ontologies). As can be observed in the figure, the contributions collectively span the entire space.
Classification of the keywords of the papers in this Special Issue across the JOWO dimensions introduced above; keywords sharing the same colour belong to the same paper.
A decade of community building has turned JOWO into what it is today in 2026, a broadly endorsed platform for multi-disciplinary research, bringing together the core topics of the Applied Ontology community: from foundational ontologies and the core conceptual discussions involved, to the wider communities applying knowledge-based tools and technologies.
Over time, JOWO has consolidated its theoretical foundation but has also progressively opened towards application-orientated work, reflecting an increasing engagement with real-world problems and with the broader research environment in closely related fields.
The analysis of trends across JOWO points to a community that is both evolving and stable. While a widening spectrum of applications and emerging topics contribute to its diversity, foundational questions continue to provide a coherent backbone to the venue. Importantly, the increasing relevance of data-driven work does not overshadow foundational perspectives; rather these remain central. Semantic and conceptual analyses remain a core aspect of JOWO’s identity.
Despite this, JOWO plays a distinctive role in parallel with more established venues such as FOIS. JOWO offers a space where new ideas and approaches can be explored at an earlier stage, before reaching full consolidation. In this sense, JOWO functions as a site of experimentation where new directions can be tested and refined – an incubator for the applied ontology community.
Looking ahead, this unique capacity to balance foundational reflection with exploratory and applied work suggests a promising trajectory, especially in a research landscape that increasingly values measurable outcomes, sometimes at the expense of conceptual analysis. We believe strongly that this is an indication that we can expect another strong decade for the Joint Ontology Workshops, and we are looking forward to the special issues celebrating their 20th Anniversary.
Footnotes
Acknowledgements
The authors are grateful to Bernd Ludwig and Noah Meißner for discussing data analytics and providing valuable data for the analysis of research trends in JOWO and FOIS. We thank Francesca Vitali for the preparation of the corpora. They moreover thank Stefano Borgo for providing feedback on an earlier version of this paper.
Funding
The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: Oliver Kutz acknowledges the financial support through the ‘Abstractron’ project funded by the Autonome Provinz Bozen – Südtirol (Autonomous Province of Bolzano/Bozen) through the Research Südtirol/Alto Adige 2022 Call. Guendalina Righetti was supported by the European Union (ERC Advanced Grant, C-FORS: Construction in the Formal Sciences, awarded to Øystein Linnebo, project number 101054836).
Declaration of Conflicting Interests
The authors declared no potential conflicts of interest with respect to the research, authorship and/or publication of this article.