> On 19 Nov 2019, at 15:24, Jan Voskuil <jan.vosk...@taxonic.com> wrote: > > A very late after-burner (I am currently involved in similar discussions and > stumbled upon this thread by accident): > Have a look at Uschold's "Demystifying OWL". It is a good read, especially > the two pages on punning. > While there is little to add to what Irene and David have said, I think it is > important to stress that when people say things like "I have a set of > triples, and these imply OWL Full", what really is being said is that there > is a deep and serious problem with the model being used. OWL Full does not > solve these problems, nor does it cause interesting things to happen. It only > guides an OWL-inferencer around the underlying problems, so that it does not > break down. The original intention of the underlying model is not achieved, > however. Introspective tools will not behave as expected. Irene's example > about the BMW 240i is hard in any formal language, because of type theory > being counter-intuitive. There is nothing one can do about that. Instead of > trying to out-smart the semantics of RDF, it is most often better to bite the > bullet and solve the issue in the model itself --- and accept the added > complexity. >
Hi Jan, Personally, I think that characterisation goes a bit too far although the core sentiment is a good approach. Technically, all "OWL Full” really means is that the model uses logic that is, for example, based in First Order Logic [1] rather than in Description Logic [2]. Using DL often means the modeller has chosen “decidability” over “representational capability” wrt their model. That’s fine if DL is sufficient to model your domain of interest. But, what if it’s not? There are certainly cases where the use of first order logic models and engines have solved real-world problems. I imagine most folks don’t know that “The relational model (RM) for database management is an approach to managing data using a structure and language consistent with first-order predicate logic,” (quote from https://en.wikipedia.org/wiki/Relational_model <https://en.wikipedia.org/wiki/Relational_model>) There’s even an ISO standard logic language supporting for those cases - Common Logic [3] is an ISO standard that “provide for the expression of arbitrary first-order logical sentences”. There are also standard data models, ISO 15926-2 [4] for example, that are based in higher-than-DL order logic (full disclosure, with previous employers I worked in ISO on 15926 and ISO 10303 STEP). I agree that there are many, many, many “bad” models in industry. However, there are plenty of quality models that use logic higher than DL - they just require more expertise to create and use (e.g. logicians may be needed in the project). I happen to have studied math and have been surprised at times to find ontologist/modelers who don’t understand any of this stuff because they never studied set theory or logic. These more complex ideas require some background education/knowledge in order to use them properly. However, I’m sure you know the quote: Everything Should Be Made as Simple as Possible, But Not Simpler. Apologies for the long reply and all the links. Just something to which I happen to have had quite a bit of exposure, although am not truly an expert, as I spent a lot of time debating academics and logicians in ISO-land when working for IBM. Cheers, David [1] ISO/IEC 24707:2018. Information technology — Common Logic (CL) — A framework for a family of logic-based languages See https://www.iso.org/standard/66249.html <https://www.iso.org/standard/66249.html> [2] First-order Logic Seehttps://en.wikipedia.org/wiki/First-order_logic <seehttps://en.wikipedia.org/wiki/First-order_logic> [3] Description Logic See https://en.wikipedia.org/wiki/Description_logic [4] ISO 15926-2:2003. Industrial automation systems and integration — Integration of life-cycle data for process plants including oil and gas production facilities — Part 2: Data model See https://www.iso.org/standard/29557.html > On Tuesday, October 8, 2019 at 5:31:08 PM UTC+2, Bohms, H.M. (Michel) wrote: > > In: > > https://www.w3.org/2006/07/SWD/SKOS/skos-and-owl/master.html > <https://www.w3.org/2006/07/SWD/SKOS/skos-and-owl/master.html> > > its is said: > > “ > > To illustrate these patterns, let's start with the following semi-formal > conceptualisation: > > ex:mountains rdf:type skos:Concept; > > skos:prefLabel "Mountains"@en. > > > ex:himalayas rdf:type skos:Concept; > > skos:prefLabel "Himalayas"@en; > > skos:broader ex:mountains. > > > ex:everest rdf:type skos:Concept; > > skos:prefLabel "Everest"@en; > > skos:broader ex:himalayas. > > Overlay SKOS with OWL > > In this pattern, we use OWL to overlay additional semantics on the same > vocabulary, e.g. by adding the following triples: > > ex:mountains rdf:type owl:Class. > > > ex:himalayas rdf:type owl:Class; > > rdfs:subClassOf ex:mountains. > > > ex:everest rdf:type ex:himalayas. > > If the two sets of triples are merged, then this pattern necessarily leads to > an OWL Full representation, because an instance of skos:Concept might also be > an instance of owl:Class. > > > “ > > > Is the red statement really true? And if yes, is it really an issue here? > > > (maybe it was under owl1 but under owl2 not different?) > > > thx for advice, Michel > > > > > > Dr. ir. H.M. (Michel) Böhms > Senior Data Scientist > > > T +31888663107 > M +31630381220 > E michel.bo...@tno.nl <> > Location > <https://www.google.com/maps/place/TNO+-+Locatie+Delft+-+Stieltjesweg/@52.000788,4.3745183,17z/data=!3m1!4b1!4m5!3m4!1s0x47c5b58c52869997:0x56681566be3b8c88!8m2!3d52.000788!4d4.376707> > > > > <http://www.tno.nl/> > This message may contain information that is not intended for you. If you are > not the addressee or if this message was sent to you by mistake, you are > requested to inform the sender and delete the message. 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