FOIS’18 conference report

To some perhaps surprisingly, despite being local organizer, I could attend all sessions of the 10th International Conference Formal Ontology in Information Systems as participant (cf. running around for last-minute things). It just wasn’t as much of a trip as it usually is: only 15 minutes to town at the Atlantic Imbizo conference venue, which is situated between the Clock Tower and (award-winning) Zeitz MOCAA at Cape Town’s V&A Waterfront. This blog post has turned into a longer post than intended—yet, there’s still so much left out to talk about—and it is divided up into sections on keynotes, presentations, ontologies, and the (ontologically inappropriate basket of) other things.

 

Keynotes

The first keynote was presented by (emeritus) professor in philosophy Peter Simons from Trinity College Dublin and Universität Salzburg, on the ontology of aboutness (slides).

Peter Simon during his keynote talk

That may sound a bit abstract, but it is not unusual for some information system that it will have to record statements about something, such as different medical opinions, changes of policies, plans or expectations, and we need a way to represent that and deal with it. Simons discussed several earlier proposals before proposing his own, which includes as main entities a bearer, act, time, act-type, mental content, mental content type, intentional objects, referent, and referent type (slide 16), and then variants for pictorial and linguistic (speech and writing). And, in closing, his advice of “Don’t get involved in irrelevant philosophical disputes”.

The second keynote was presented by Alessandro Oltramari, who works at Bosch Research and Technology Centre in Pittsburgh, USA. He presented several of Bosch’s projects where ontologies are used in one way or another (slides) and that he was involved in. One of them was about knowledge-based intelligent IoT and another on an emergency assistant, or, in business sales parlance, a “personal guardian angel” mobile device that has location awareness, safety information of those locations, a decision support system for alternate route computation, and automatic escalation. The ontologies used include the foundational ontology DOLCE, the domain ontology of semantic sensor networks (SSN) from the W3C, and specific schemas developed in-house. Another project on a knowledge-based chatbot for healthcare policies links up DOLCE, schema.org, and some in-house schemas with Highmark-specific information (and is not ashamed of using SKOS). Om my question what methods and methodologies were used for the in-house ontology development, the (disappointing) answer was, unfortunately, only “DOLCE and OntoClean”, but the former is neither a method nor a methodology (it implies a top-down approach), and the latter is some 15 years old, as if nothing has happened in ontology engineering in the meantime (more about that further below). Regardless, it was good to see that ontologies are being used in industry.

The third keynote (slides) was by Riichiro Mizoguchi from the Japan Advanced Institute of Science and Technology (JAIST), on a state-centric methodology, which I’ll leave for a separate post.

Riichiro Mizoguchi during his keynote talk.

 

Presentations

The report on the presentations easily could take up several pages, but I’ll try to keep it short, lest otherwise this post never gets posted. The first session of the conference was on foundations. This included Antony Galton’s assessment of the treatment of time in upper ontologies [1]. It was mildly entertaining in that it turned out that BFO would need abstract things for its treatment of time (which it doesn’t have and doesn’t like) and adheres to Newtonian physics cf. the latest scientific theories. It is definitely on my list of papers to read in more detail. Another paper-for-printing to read is Torsten Hahmann’s work on mereotopology, which extends it to multidimensional space [2]. A nice bonus (though it ought not to be perceived as such) is that at least the theorems in the paper have been proved with Prover9 and Vampire (cf. having to double-check them manually). Laure Vieu presented a proposal for a graph-based approach to represent structure among the components of an entity [3], which is apparently different from the graph-based approach for representing molecules (within the Semantic Web context); I’ll have to look at that in more detail, for it sounds like it might be of some use for the parts aspects of part-whole relations.

Besides such theoretical contributions that are rather distant from applications, there were two of note that were motivated from praxis more clearly. One was about the ontological foundations of competition and the sort of competitive relations there are [4], which was presented by Tiago Prince Sales. The other one was presented by Pawel Garbacz, whose presentation conveyed more than the paper so as to get a real feel of the problem, being identity criteria for localities [5], with complicating use cases extracted from a Polish history project. He presented some examples of changes and a proposal for how to identify a locality/settlement. For instance, settlements can get moved altogether, have a population-only move, split into two, be merged, renamed and renamed again, deserted by a population and repopulated and renamed, and so on. When is it the same settlement and when is it another one? The paper [5] describes a first solution for identity criteria with an event-based approach to identity of localities.

My presentation on part-whole relations in Zulu language and culture [6] was scheduled in the ‘applications’ session, which had positive feedback and some pointers that may assist with future work.

 

venue during a Q&A session

Ontologies

Besides presentations, there was a discussion session on “what constitutes a good ontology paper?” for the Applied Ontology journal. Seeing the ontology papers at FOIS now, they should have done such as session for FOIS as well. There are four papers in the proceedings describing OWL files: “Amnestic forgery” (AF, conceptual metaphors) [7] presented by Mehwish Alam, UNiCS for research and innovation policy [8] presented by Fernando Roda, SAREF4Health [9] presented by João Moreira, and religious and spiritual belief (ORSB) [10] presented by Stefan Schulz. Skimming through each paper, AF, UNiCS and ORSB do not use a methodology explicitly, none of them uses existing methods, but they all do use a foundational or top-level ontology or the WordNet material, and then it’s cool enough to get into FOIS, apparently. This is a bit disappointing. At least SAREF4Health presented a set of competency questions, a systematic approach and broader framework, and some evaluation, and ORSB reuses not only top-level and top-domain ontologies but also tests some patterns. AF and ORSB have some interest to it as they’re addressing relatively novel modeling issues to solve and the ORSB discussion could be used more broadly for any “terms of dubious reference”. UNiCS is not really an ontology but an information model or, at best, a conceptual data model (e.g. calling “SCOPUS subject” an ontology is pushing it a bit too far); it makes their OBDA scenario easier to realize, true, but that’s a separate discussion. Fig 1 of SAREF4Health doesn’t look any better either, which has all the hallmarks of a plain UML Class Diagram (attributes with data types and such), with object diagram components attached and coloured in and annotated with OntoUML. SAREF4Health’s other downsides are things like “implementing the ontology as RDF” that just hurts to read (it is left implicit for AF that is plugged into the LOD cloud), as is the download in Turtle format (cf. the required exchange syntax of OWL 2), which isn’t even available at the provided link when you click on it (copy-paste gets you in the right direction), but is [I think] in some github sub-directory that has a whole bunch of ttl files with neither head nor tail, but one of them is called saref4health.ttl. On first inspection, it has plenty of data properties and data type use, and the class-as-instance issue here and there (e.g., ‘Rechargeable Lithium Polymer battery’ as instance cf. class), and others (e.g., a ‘series’ of measurements is not a subclass of a measurement) and very many classes directly subsumed by top, though some are knock-on effects from imports.

And then ontologists at FOIS deplored that there are many domain ontologies that are of poor quality and artifacts presented as ontologies but aren’t. The FOIS reviewers themselves apparently can’t even get their act together in the reviewing process, where artifacts that are sold as domain ontologies but aren’t (UNiCS, SAREF4Health) make it not only through the reviewing process but, moreover, even get a best paper award from the PC chairs (SAREF4Health). The PC chairs wanted to make a political statement to communicate that FOIS accepts domain ontology papers. It is good that the FOIS topics are becoming less narrow and I’m not saying they are pointless papers or lousy artifacts per sé—they are useful reference papers and UNiCS and SAREF4Health perform the application tasks they’re supposed to be performing, which is a good thing. Maybe, collectively, ontology developers can’t do better or don’t need to do better w.r.t. applied ontology? Either way, once upon a time there were principles for what ontologies are; what happened to that? Also, there are multiple methodologies for domain ontology development, and there are a myriad of methods and tools, which have been mostly ignored. For instance, using one foundational ontology over another ‘just because I know x’ is neither a scientific nor a sound engineering approach. There are comparisons, requirements, and a mix of the two to help you figure out which one is the best to use; an early tool for that is ONSET, the ONtology Selection and Explanation Tool, developed by Zubeida Khan (more data). To name one example.

Coincidentally, ontology engineering papers with such a content do not, or very rarely, make it into FOIS; but just that they don’t (because they’re typically not philosophical enough), doesn’t mean they don’t exist. Just in case a FOIS ontologist would like to explore methods, methodologies and tools for ontology development: ESWC, EKAW, and K-CAP are good/top conferences covering such topics in whole or in part, and Chapter 5 of the ontology engineering textbook provides a sampling as well (as do some other sections in Block II). Considering my critical comments, one may ask whether my ontologies and ontology papers are any better, or anyone else’s for that matter. Perhaps, perhaps not. You can check for yourself some of my recent papers on domain ontologies that also have OWL files[1] that I was involved in developing; one paper was intended as a reference paper for the domain ontology [11], another paper was a bit of both domain ontology and some framework [12], and yet another turned into a core ontology [13] (v1, with the main categories; there’s an updated version for the relations).

Anyway, returning to the first sentence of this section: the open forum discussion did not make it any clearer as to what would be the characteristics of a good ontology paper for the Applied Ontology journal (or FOIS, for that matter). Mainly just Protégé screenshots certainly is not, but opinions varied as to what would be. Going by examples of the ontology papers that made it through: use of a top-level or foundational ontology and some modeling issues and solutions seems to be preferred, evaluation and usage & uptake as a nice-to-have. Is developing an (domain) ontology science? That question wasn’t answered unanimously; I think it was leaning towards a ‘mostly no’ w.r.t. applied ontology but it may be if it’s the first to solve a modeling issue. How to evaluate the ontology? Another question without a satisfactory answer. Overall, the criteria for an ontology paper—let alone for the ontology itself—are “TBD” and meanwhile one has to hope that one will get a supportive ‘reviewer 2’.

 

Other

In case you have clicked-though to one or more of the listed papers, you may have noticed that the FOIS’18 proceedings are Open Access—paid for by those who registered for the conference (it was calculated in the registration fee). I suppose the next FOIS organisers and the IAOA exec may like your opinion on that approach.

mentors of the early career symposium papers

Besides the best paper award for SAREF4Health [9], there were two “distinguished paper awards”, which went to aforementioned paper on the graph-based approach for structured universals by Laure Vieu and Claudio Masolo [3] and to the foundational ontologies for units of measure by Michael Grüninger and co-authors [14]. The early career symposium went well and from hearsay they had a good social activity, too. There were lots of interesting conversations, networking, good food, and so on, and lots more to write about. There are also more photos.

Some of the postgraduate students and a recent PhD graduate in the spotlight at the closing ceremony, being thanked for chairing the sessions.

Last, but not least: the next FOIS in 2020 will be in Bolzano, Italy, as part of a ‘Bolzano summer of knowledge’ with more co-located conferences, workshops, and summer schools.

 

References

[1] Antony Galton. The treatment of time in upper ontologies. Proc. of FOIS’18. IOS Press, 306: 33-46.

[2] Thorsten Hahmann. On Decomposition Operations in a Theory of Multidimensional Qualitative Space. Proc. of FOIS’18. IOS Press, 306: 173-186.

[3] Claudio Masolo, Laure Vieu. Graph-Based Approaches to Structural Universals and Complex States of Affairs. Proc. of FOIS’18. IOS Press, 306: 69-82.

[4] Tiago Prince Sales, Daniele Porello, Nicola Guarino, Giancarlo Guizzardi, John Mylopoulos. Ontological Foundations of Competition. Proc. of FOIS’18. IOS Press, 306: 96-112.

[5] Pawel Garbacz, Agnieszka Ławrynowicz, Bogumił Szady. Identity criteria for localities. Proc. of FOIS’18. IOS Press, 306: 47-56.

[6] C. Maria Keet, Langa Khumalo. On the Ontology of Part-Whole Relations in Zulu Language and Culture. Proc. of FOIS’18. IOS Press, 306: 225-238.

[7] Aldo Gangemi, Mehwish Alam, Valentina Presutti. Amnestic Forgery: An Ontology of Conceptual Metaphors. Proc. of FOIS’18. IOS Press, 306: 159-172.

[8] Alessandro Mosca, Fernando Roda, Guillem Rull. UNiCS – The Ontology for Research and Innovation Policy Making. Proc. of FOIS’18. IOS Press, 306: 200-210.

[9] João Moreira, Luís Ferreira Pires, Marten van Sinderen, Laura Daniele. SAREF4health: IoT Standard-Based Ontology-Driven Healthcare Systems. Proc. of FOIS’18. IOS Press, 306: 239-252.

[10] Stefan Schulz, Ludger Jansen. Towards an Ontology of Religious and Spiritual Belief. Proc. of FOIS’18. IOS Press, 306: 253-260.

[11] Keet, C.M., Lawrynowicz, A., d’Amato, C., Kalousis, A., Nguyen, P., Palma, R., Stevens, R., Hilario, M. The Data Mining OPtimization ontology. Web Semantics: Science, Services and Agents on the World Wide Web, 2015, 32:43-53.

[12] Chavula, C., Keet, C.M. An Orchestration Framework for Linguistic Task Ontologies. 9th Metadata and Semantics Research Conference (MTSR’15), Garoufallou, E. et al. (Eds.). Springer CCIS vol. 544, 3-14.

[13] Keet, C.M. A core ontology of macroscopic stuff. 19th International Conference on Knowledge Engineering and Knowledge Management (EKAW’14). K. Janowicz et al. (Eds.). 24-28 Nov, 2014, Linkoping, Sweden. Springer LNAI vol. 8876, 209-224.

[14] Michael Grüninger, Bahar Aameri, Carmen Chui, Torsten Hahmann, Yi Ru. Foundational Ontologies for Units of Measure. Proc. of FOIS’18. IOS Press, 306: 211-224.

[1] I have others developed as part of methods & tools research

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ISAO 2018, Cape Town, ‘trip’ report

The Fourth Interdisciplinary School on Applied Ontology has just come to an end, after five days of lectures, mini-projects, a poster session, exercises, and social activities spread over six days from 10 to 15 September in Cape Town on the UCT campus. It’s not exactly fair to call this a ‘trip report’, as I was the local organizer and one of the lecturers, but it’s a brief recap ‘trip report kind of blog post’ nonetheless.

The scientific programme consisted of lectures and tutorials on:

The linked slides (titles of the lectures, above) reveal only part of the contents covered, though. There were useful group exercises and plenary discussion with the ontological analysis of medical terms such as what a headache is, a tooth extraction, blood, or aspirin, an exercises on putting into practice the design process of a conceptual modelling language of one’s liking (e.g.: how to formalize flowcharts, including an ontological analysis of what those elements are and ontological commitments embedded in a language), and trying to prove some theorems of parthood theories.

There was also a session with 2-minute ‘blitztalks’ by participants interested in briefly describing their ongoing research, which was followed by an interactive poster session.

It was the first time that an ISAO had mini-projects, which turned out to have had better outcomes than I expected, considering the limited time available for it. Each group had to pick a term and investigate what it meant in the various disciplines (task description); e.g.: what does ‘concept’ or ‘category’ mean in psychology, ontology, data science, and linguistics, and ‘function’ in manufacturing, society, medicine, and anatomy? The presentations at the end of the week by each group were interesting and most of the material presented there easily could be added to the IAOA Education wiki’s term list (an activity in progress).

What was not a first-time activity, was the Ontology Pub Quiz, which is a bit of a merger of scientific programme and social activity. We created a new version based on questions from several ISAO’18 lecturers and a few relevant questions created earlier (questions and answers; we did only questions 1-3,6-7). We tried a new format compared to the ISAO’16 quiz and JOWO’17 quiz: each team had 5 minutes to answer a set of 5 questions, and another team marked the answers. This set-up was not as hectic as the other format, and resulted in more within-team interaction cf. among all participants interaction. As in prior editions, some questions and answers were debatable (and there’s still the plan to make note of that and fix it—or you could write an article about it, perhaps :)). The students of the winning team received 2 years free IAOA membership (and chocolate for all team members) and the students of the other two teams received one year free IAOA membership.

Impression of part of the poster session area, moving into the welcome reception

As with the three previous ISAO editions, there was also a social programme, which aimed to facilitate getting to know one another, networking, and have time for scientific conversations. On the first day, the poster session eased into a welcome reception (after a brief wine lapse in the coffee break before the blitztalks). The second day had an activity to stretch the legs after the lectures and before the mini-project work, which was a Bachata dance lesson by Angus Prince from Evolution Dance. Not everyone was eager at the start, but it turned out an enjoyable and entertaining hour. Wednesday was supposed to be a hike up the iconic Table Mountain, but of all the dry days we’ve had here in Cape Town, on that day it was cloudy and rainy, so an alternative plan of indoor chocolate tasting in the Biscuit Mill was devised and executed. Thursday evening was an evening off (from scheduled activities, at least), and Friday early evening we had the pub quiz in the UCT club (the campus pub). Although there was no official planning for Saturday afternoon after the morning lectures, there was again an attempt at Table Mountain, concluding the week.

The participants came from all over the world, including relatively many from Southern Africa with participants coming also from Botswana and Mauritius, besides several universities in South Africa (UCT, SUN, CUT). I hope everyone has learned something from the programme that is or will be of use, enjoyed the social programme, and made some useful new contacts and/or solidified existing ones. I look forward to seeing you all at the next ISAO or, better, FOIS, in 2020 in Bolzano, Italy.

Finally, as a non-trip-report comment from my local chairing viewpoint: special thanks go to the volunteers Zubeida Khan for the ISAO website, Zola Mahlaza and Michael Harrison for on-site assistance, and Sam Chetty for the IT admin.

From ontology verbalisation to language learning exercises

I’m aware that to most people ‘playing with’ (investigating) ontologies and isiZulu does not sound particularly useful on the face of it. Yet, there’s the some long-term future music, like eventually being able to generate patient discharge notes in one’s own language, which will do its bit to ameliorate the language barrier in healthcare in South Africa so that patients at least will adhere to the treatment instructions a little better, and therewith receive better quality healthcare. But benefits in the short-term might serve something as well. To that end, I proposed an honours project last year, which has been completed in the meantime, and one of the two interesting outcomes has made it into a publication already [1]. As you may have guessed from the title, it’s about automation for language learning exercises. The results will be presented at the 6th Workshop on Controlled Natural Language, in Maynooth, Ireland in about 2 weeks time (27-28 August). In the remainder of this post, I highlight the main contributions described in the paper.

First, regarding the post’s title, one might wonder what ontology verbalisation has to do with language learning. Nothing, really, except that we could reuse the algorithms from the controlled natural language (CNL) for ontology verbalisation to generate (computer-assisted) language learning exercises whose answers can be computed and marked automatically. That is, the original design of the CNL for things like pluralising nouns, verb conjugation, and negation that is used for verbalising ontologies in isiZulu in theory [2] and in practice [3], was such that the sentence generator is a detachable module that could be plugged in elsewhere for another task that needs such operations.

Practically, the student who designed and developed the back-end, Nikhil Gilbert, preferred Java over Python, so he converted most parts into Java, and added a bit more, notably the ‘singulariser’, a sentence scrabble, and a sentence generator. Regarding the sentence generator, this is used as part of the exercises & answers generator. For instance, we know that humans and the roles they play (father, aunt, doctor, etc.) are mostly in isiZulu’s noun classes 1, 2, 1a, 2a, or 3a, that those classes do not (or rarely?) have non-human nouns and generally it holds for all humans and their roles that they can ‘eat’, ‘talk’ etc. This makes it relatively easy create a noun chain and a verb chain list to mix and match nouns with verbs accordingly (hurrah! for the semantics-based noun class system). Then, with the 231 nouns and 59 verbs in the newly constructed mini-corpus, the noun chain and the verb chain, 39501 unique question sentences could be generated, using the following overall architecture of the system:

Architecture of the CNL-driven CALL system. The arrows indicate which upper layer components make use of the lower layer components. (Source: [1])

From a CNL perspective as well as the language learning perspective, the actual templates for the exercises may be of interest. For instance, when a learner is learning about pluralising nouns and their associated verb, the system uses the following two templates for the questions and answers:

Q: <prefixSG+stem> <SGSC+VerbRoot+FV>
A: <prefixPL+stem> <PLSC+VerbRoot+FV>
Q: <prefixSG+stem> <SGSC+VerbRoot+FV> <prefixSG+stem>
A: <prefixPL+stem> <PLSC+VerbRoot+FV> <prefixPL+stem>

The answers can be generated automatically with the algorithms that generate the plural noun (from ‘prefixSG’ to ‘prefixPL’) and add the plural subject concord (from ‘SGSC’ to ‘PLSC’, in agreement with ‘prefixPL’), which were developed as part of the GeNI project on ontology verbalization. This can then be checked against what the learner has typed. For instance, a generated question could be umfowethu usula inkomishi and the correct answer generated (to check the learner’s response against) is abafowethu basula izinkomishi. Another example is generation of the negation from the positive, or, vv.; e.g.:

Q: <PLSC+VerbRoot+FV>
A: <PLNEGSC+VerbRoot+NEGFV>

For instance, the question may present batotoba and the correct answer is then abatotobi. In total, there are six different types of sentences, with two double, like the plural above, hence a total of 16 templates. It is not a lot, but it turned out it is one of the very few attempts to use a CNL in such way: there is one paper that also will be presented at CNL’18 in the same session [4], and an earlier one [5] uses a fancy grammar system (that we don’t have yet computationally for isiZulu). This is not to be misunderstood as that this is one of the first CNL/NLG-based system for computer-assisted language learning—e.g., there’s assistance in essay writing, grammar concept question generation, reading understanding question generation—but curiously very little on CNLs or NLG for the standard entry-level type of questions to learn the grammar. Perhaps the latter is considered ‘boring’ for English by now, given all the resources. However, thousands of students take introduction courses in isiZulu each year, and some automation can alleviate the pressure of routine activities from the lecturers. We have done some evaluations with learners—with encouraging results—and plan to do some more, so that it may eventually transition to actual use in the courses; that is: TBC…

 

References

[1] Gilbert, N., Keet, C.M. Automating question generation and marking of language learning exercises for isiZulu. 6th International Workshop on Controlled Natural language (CNL’18). IOS Press. Co. Kildare, Ireland, 27-28 August 2018. (in print)

[2] Keet, C.M., Khumalo, L. Toward a knowledge-to-text controlled natural language of isiZulu. Language Resources and Evaluation, 2017, 51(1): 131-157.

[3] Keet, C.M. Xakaza, M., Khumalo, L. Verbalising OWL ontologies in isiZulu with Python. The Semantic Web: ESWC 2017 Satellite Events, Blomqvist, E. et al. (eds.). Springer LNCS vol. 10577, 59-64.

[4] Lange, H., Ljunglof, P. Putting control into language learning. 6th International Workshop on Controlled Natural language (CNL’18). IOS Press. Co. Kildare, Ireland, 27-28 August 2018. (in print)

[5] Gardent, C., Perez-Beltrachini, L. Using FB-LTAG Derivation Trees to Generate Transformation-Based Grammar Exercises. Proc. of TAG+11, Sep 2012, Paris, France. pp117-125, 2012.

An Ontology Engineering textbook

My first textbook “An Introduction to Ontology Engineering” (pdf) is just released as an open textbook. I have revised, updated, and extended my earlier lecture notes on ontology engineering, amounting to about 1/3 more new content cf. its predecessor. Its main aim is to provide an introductory overview of ontology engineering and its secondary aim is to provide hands-on experience in ontology development that illustrate the theory.

The contents and narrative is aimed at advanced undergraduate and postgraduate level in computing (e.g., as a semester-long course), and the book is structured accordingly. After an introductory chapter, there are three blocks:

  • Logic foundations for ontologies: languages (FOL, DLs, OWL species) and automated reasoning (principles and the basics of tableau);
  • Developing good ontologies with methods and methodologies, the top-down approach with foundational ontologies, and the bottom-up approach to extract as much useful content as possible from legacy material;
  • Advanced topics that has a selection of sub-topics: Ontology-Based Data Access, interactions between ontologies and natural languages, and advanced modelling with additional language features (fuzzy and temporal).

Each chapter has several review questions and exercises to explore one or more aspects of the theory, as well as descriptions of two assignments that require using several sub-topics at once. More information is available on the textbook’s page [also here] (including the links to the ontologies used in the exercises), or you can click here for the pdf (7MB).

Feedback is welcome, of course. Also, if you happen to use it in whole or in part for your course, I’d be grateful if you would let me know. Finally, if this textbook will be used half (or even a quarter) as much as the 2009/2010 blogposts have been visited (around 10K unique visitors since posting them), that would mean there are a lot of people learning about ontology engineering and then I’ll have achieved more than I hoped for.

UPDATE: meanwhile, it has been added to several open (text)book repositories, such as OpenUCT and the Open Textbook Archive, and it has been featured on unglue.it in the week of 13-8 (out of its 14K free ebooks).

Ontology pub quiz questions of ISAO 2016 and JOWO 2017

In 2016 when I was a PC chair of the International School for Applied Ontology (ISAO 2016), the idea of organising a contest for the participants turned into a pub quiz somehow. The lecturers provided one or more questions on the topics they’d be teaching and I added a few as well. This set of ISAO16 ontology pub quiz questions is now finally online. It comes with the warning that it is biased toward the topics covered at ISAO 2016, and it turned out that there were a few questions not well formulated and/or not everyone agreed with the answer.

Notwithstanding, it was deemed sufficiently ok as idea in that the general chair of the Joint Ontology Workshops (JOWO 2017) wanted one for JOWO 2017 as well. Several questions were thrown out of the ISAO16 set for various reasons and more general Ontology questions made their way in, as well as a few ‘fun’ and trivia ones in the hope to add some more entertainment to the ontology pub quiz. The JOWO17 pub quiz question set with answers is now also online to play with, which, in my opinion, is a nicer set than the ISAO16 one. Here are a few questions to give you a taste of it:

  • Where/when can a pointless theory be relevant?
  • What is the goal of guerrilla ontology?
  • No Italian pizza has fruit as topping. Which of the following is (an)/are Italian pizza(s)? Pizza Hawaii, Pizza margherita, Pizza bianca romana (‘white roman pizza’)
  • When was the earliest published occurrence of the word “ontology”?

It turned out that it still was not entirely free of debate. If you disagree with one of the answers now, then let me paraphrase Stefano Borgo, who co-ran the JOWO17 pub quiz at the Irish pub in Bolzano on 23 September: maybe there’s something there to write up and submit a paper to FOIS 2018 :-). Or you can write it in the blog post comments section below, so that those questions will/should not be recycled and I can add longer answers to the questions.

Orchestrating 28 logical theories of mereo(topo)logy

Parts and wholes, again. This time it’s about the logic-aspects of theories of parthood (cf. aligning different hierarchies of (part-whole) relations and make them compatible with foundational ontologies). I intended to write this post before the Ninth Conference on Knowledge Capture (K-CAP 2017), where the paper describing the new material would be presented by my co-author, Oliver Kutz. Now, afterwards, I can add that “Orchestrating a Network of Mereo(topo) logical Theories” [1] even won the Best Paper Award. The novelties, in broad strokes, are that we figured out and structured some hitherto messy and confusing state of affairs, showed that one can do more than generally assumed especially with a new logics orchestration framework, and we proposed first steps toward conflict resolution to sort out expressivity and logic limitations trade-offs. Constructing a tweet-size “tl;dr” version of the contents is not easy, and as I have as much space here on my blog as I like, it ended up to be three paragraphs here: scene-setting, solution, and a few examples to illustrate some of it.

 

Problems

As ontologists know, parthood is used widely in ontologies across most subject domains, such as biomedicine, geographic information systems, architecture, and so on. Ontology (the philosophers) offer a parthood relation that has a bunch of computationally unpleasant properties that are structured in a plethora of mereologicial and meretopological theories such that it has become hard to see the forest for the trees. This is then complicated in practice because there are multiple logics of varying expressivity (support more or less language features), with the result that only certain fragments of the mereo(topo)logical theories can be represented. However, it’s mostly not clear what can be used when, during the ontology authoring stage one may want to have all those features so as to check correctness, and it’s not easy to predict what will happen when one aligns ontologies with different fragments of mereo(topo)logy.

 

Solution

We solved these problems by specifying a structured network of theories formulated in multiple logics that are glued together by the various linking constructs of the Distributed Ontology, Model, and Specification Language (DOL). The ‘structured network of theories’-part concerns all the maximal expressible fragments of the KGEMT mereotopological theory and five of its most well-recognised sub-theories (like GEM and MT) in the seven Description Logics-based OWL species, first-order logic, and higher order logic. The ‘glued together’-part refers to relating the resultant 28 theories within DOL (in Ontohub), which is a non-trivial (understatement, unfortunately) metalanguage that has the constructors for the glue, such as enabling one to declare to merge two theories/modules represented in different logics, extending a theory (ontology) with axioms that go beyond that language without messing up the original (expressivity-restricted) ontology, and more. Further, because the annoying thing of merging two ontologies/modules can be that the merged ontology may be in a different language than the two original ones, which is very hard to predict, we have a cute proof-of-concept tool so that it assists with steps toward resolution of language feature conflicts by pinpointing profile violations.

 

Examples

The paper describes nine mechanisms with DOL and the mereotopological theories. Here I’ll start with a simple one: we have Minimal Topology (MT) partially represented in OWL 2 EL/QL in “theory8” where the connection relation (C) is just reflexive (among other axioms; see table in the paper for details). Now what if we add connection’s symmetry, which results in “theory4”? First, we do this by not harming theory8, in DOL syntax (see also the ESSLI’16 tutorial):

logic OWL2.QL
ontology theory4 =
theory8
then
ObjectProperty: C Characteristics: Symmetric %(t7)

What is the logic of theory4? Still in OWL, and if so, which species? The Owl classifier shows the result:

 

Another case is that OWL does not let one define an object property; at best, one can add domain and range axioms and the occasional ‘characteristic’ (like aforementioned symmetry), for allowing arbitrary full definitions pushes it out of the decidable fragment. One can add them, though, in a system that can handle first order logic, such as the Heterogeneous toolset (Hets); for instance, where in OWL one can add only “overlap” as a primitive relation (vocabulary element without definition), we can take such a theory and declare that definition:

logic CASL.FOL
ontology theory20 =
theory6_plus_antisym_and_WS
then %wdef
. forall x,y:Thing . O(x,y) <=> exists z:Thing (P(z,x) /\ P(z,y)) %(t21)
. forall x,y:Thing . EQ(x,y) <=> P(x,y) /\ P(y,x) %(t22)

As last example, let me illustrate the notion of the conflict resolution. Consider theory19—ground mereology, partially—that is within OWL 2 EL expressivity and theory18—also ground mereology, partially—that is within OWL 2 DL expressivity. So, they can’t be the same; the difference is that theory18 has parthood reflexive and transitive and proper parthood asymmetric and irreflexive, whereas theory19 has both parthood and proper parthood transitive. What happens if one aligns the ontologies that contain these theories, say, O1 (with theory18) and O2 (with theory19)? The Owl classifier provides easy pinpointing and tells you the profile: OWL 2 full (or: first order logic, or: beyond OWL 2 DL—top row) and why (bottom section):

Now, what can one do? The conflict resolution cannot be fully automated, because it depends on what the modeller wants or needs, but there’s enough data generated already and there are known trade-offs so that it is possible to describe the consequences:

  • Choose the O1 axioms (with irreflexivity and asymmetry on proper part of), which will make the ontology interoperable with other ontologies in OWL 2 DL, FOL or HOL.
  • Choose O2’s axioms (with transitivity on part of and proper part of), which will facilitate linking to ontologies in OWL 2 RL, 2 EL, 2 DL, FOL, and HOL.
  • Choose to keep both sets will result in an OWL 2 Full ontology that is undecidable, and it is then compatible only with FOL and HOL ontologies.

As serious final note: there’s still fun to be had on the logic side of things with countermodels and sub-networks and such, and with refining the conflict resolution to assist ontology engineers better. (or: TBC)

As less serious final note: the working title of early drafts of the paper was “DOLifying mereo(topo)logy”, but at some point we chickened out and let go of that frivolity.

 

References

[1] Keet, C.M., Kutz, O. Orchestrating a Network of Mereo(topo)logical Theories. Ninth International Conference on Knowledge Capture (K-CAP’17), Austin, Texas, USA, December 4-6, 2017. ACM Proceedings.

Part-whole relations and foundational ontologies

Part-whole relations seem like a never-ending story—and it still doesn’t bore me. In this case, the ingredients were the taxonomy of part-whole relations [1] and a couple of foundational ontologies and the aim was to link the former to the latter. But what started off with the intention to write just a short workshop note, for seemingly clear and just in need of actually doing it, turned out to be not so straightforward after all. The selected foundational ontologies were not as compatible as assumed, and creating the corresponding orchestration of OWL files was a ‘non-trivial exercise’.

What were (some of) the issues? On the one hand, there are multiple part-whole relations, which are typically named differently when they have a specific domain or range. For instance, to relate a process to a sub-process (e.g., eating involves chewing), to relate a region to a region it contains, relating portions of stuff, and so on. Those relations are fairly well established in the literature. What they do demand for, however, is clarity as to what those categories really are. For instance, with the process example, is that to be understood as Process as meant in the DOLCE ontology, or, say, Process in BFO? What if a foundational ontology does not have a category needed for a commonly used part-whole relation?

The first step to answer such questions was to assess several foundational ontologies on 1) which of the part-whole relations they have now, and which categories are present that are needed for the domain and range declarations for those common part-whole relations. I assessed that for DOLCE, BFO, GFO, SUMO, GIST, and YAMATO. This foundational ontology comparison is summarised in tables 1 and 2 in the paper that emanated from the assessment [2], entitled “A note on the compatibility of part-whole relations with foundational ontologies” that I recently presented at FOUST-II: 2nd Workshop on Foundational Ontology, Joint Ontology Workshops 2017 in Bolzano, Italy. In short: none fits perfectly for various reasons, but there are more and less suitable ontologies for a possible alignment. DOLCE and SUMO were evaluated to have the best approximations. It appeared at the workshops presentation’s Q&A session, where two of the DOLCE developers were present, that the missing Collective was an oversight, or: the ontology is incomplete and it was not an explicit design choice to exclude it. This, then, would make DOLCE the best/easiest fit.

I’ll save you the trials and tribulations creating the orchestrated OWL files. The part-whole relations, their inverses, and their proper parthood versions were manually linked to modules of DOLCE and SUMO, and automatically linked to BFO and GFO. That was an addition of 49 relations (OWL object properties) and 121 logical axioms, which were then extended further with another 11 mereotopological relations and its 16 logical axioms. These files are accessible online directly here and also listed with brief descriptions.

While there is something usable now and, by design at least, these files are reusable as well, what it also highlighted is that there are still some outstanding questions, as there already were for the top-level categories of previously aligned foundational ontologies [3]. For instance, some categories seem the same, but they’re in ‘incompatible’ parts of the taxonomy (located in disjoint branches), so then either not the same after all, or this happened unintentionally. Only GIST has been updated recently, and it may be useful if the others foundational ontologies were to be as well, so as to obtain clarity on these issues. The full interaction of part-whole relations with classical mereology is not quite clear either: there are various extensions and deviations, such as specifically for portions [4,5], but one for processes may be interesting as well. Not that such prospective theories would be usable as-is in OWL ontology development, but there are more expressive languages that start having tooling support where it could be an interesting avenue for future work. I’ll write more about the latter in an upcoming post (covering the K-CAP 2017 paper that was recently accepted).

On a last note: the Joint Ontology Workshops (JOWO 2017) was a great event. Some 100 ontologists from all over the world attended. There were good presentations, lively conversations, and it was great to meet up again with researchers I had not seen for years, finally meet people I knew only via email, and make new connections. It will not be an easy task to surpass this event next year at FOIS 2018 in Cape Town.

 

References

 

[1] Keet, C.M., Artale, A. Representing and Reasoning over a Taxonomy of Part-Whole Relations. Applied Ontology, 2008, 3(1-2):91-110.

[2] Keet, C.M. A note on the compatibility of part-whole relations with foundational ontologies. FOUST-II: 2nd Workshop on Foundational Ontology, Joint Ontology Workshops 2017, 21-23 September 2017, Bolzano, Italy. CEUR-WS Vol. (in print)

[3] Khan, Z.C., Keet, C.M. Foundational ontology mediation in ROMULUS. Knowledge Discovery, Knowledge Engineering and Knowledge Management: IC3K 2013 Selected Papers. A. Fred et al. (Eds.). Springer CCIS vol. 454, pp. 132-152, 2015. preprint

[4] Donnelly, M., Bittner, T. Summation relations and portions of stuff. Philosophical Studies, 2009, 143, 167-185.

[5] Keet, C.M. Relating some stuff to other stuff. 20th International Conference on Knowledge Engineering and Knowledge Management (EKAW’16). Blomqvist, E., Ciancarini, P., Poggi, F., Vitali, F. (Eds.). Springer LNAI vol. 10024, 368-383. 19-23 November 2016, Bologna, Italy.