Without contradicting anything Irene says (which is obviously the gold truth for the TQ environment) I'd also like to offer an additional architectural perspective (cos thats my day job) that may also be useful, and i'm always seeking to identify best practices here...
A few separate concerns here: 1. We need to be careful with statements like "mean different things" - I think this is a classic case of the httpRange14 issue - i.e. distinguishing between identifiers of "things" vs identifiers of "representations of things" Representations have shapes, i.e. sets of properties - and this is a design choice about how to model a thing 2. Under the Open World Assumption, anyone can say anything about any topic using whatever representation they choose - so this means its another design decision (at a high level of your architecture) how to manage closure of graphs in a distributed environment. (TQ is largely concerned with your local node - and supports a particular set of closure patterns, but this is all about collapsing the open world into a tractable sub graph _that you choose_ 3. The example given is actually a strong example of why (IMHO) some systems may need to support OWL punning ... The model for the concept of "Endangered Species" is inconsistent with poor old "Harry" - which usefully tells us the model is broken or not applied properly to Harry ... in fact there is no such thing as an Endangered Species as a class of all individuals. "Endangered" is a status applied explicitly to a species within a certain spatio-temporal context (usually a date of a politically negotiated determination within a given jurisdiction), Scientifically derived concepts of endangered may also co-exist - and different evidence and modelling may suggest that a designation is more or less appropriate - a species may be endangered by any rational scientific assessment, bit not declared so, or declared so and actually extinct. There is usually a "extinct in the wild" explicit status too - so the set of eagles is actually the "set of eagles in the wild" - which poor Harry isnt. There is nothing wrong with the model of Bald Eagle - it can be instance of species and a class of a set of individuals. Its just not a subclass of Endangered Species according to the model implied in the example. Endagered Species is a different thing with a relationship to a Species, and individuals may or may not be instances of both. Of course, you may manage your context to only include a given jurisdiction (or scientific viewpoints) view - in which case the model is correct but the assignment of Harry to a specimen assumed to be "in the wild" is incorrect. So you probably need to handle instances and classes in many cases - (Having done some modelling of biodiversity and Web scale citizen science interoperability concerns, this is easy for me to spot - and IMHO demonstrates the potential power of the semantic approach) On Saturday, 8 September 2018 22:32:12 UTC+3, Irene Polikoff wrote: > > Punning is the use of the same word to mean different things. > > In modeling, it is traditionally used to refer to the approach where the > same resource is used both as an instance of some class (other than the > pre-built RDFS/OWL/SHACL classes) as well as declared to be a subclass of > some class. I am excluding the pre-built classes from this because that > takes us into a topic of meta modeling which can be seen as related, but is > somewhat different. > > My e-mail was about this topic and the differences between a concept and a > set of occurrences of this concept in the world. > > When a modeler defines a class they make statements that must be true for > all class members and they define characteristics (properties) of such > members. A classic example of this (classic because you come across it > described in Wikipedia and in discussions amongst the modeling community) > is Bold Eagle as a specie vs Harry, a Bold Eagle. Bold Eagle is an > endangered specie. Harry, however, is not endangered - that is unless > someone is currently trying to kill it. Harry has his own properties and we > need a class to describe these properties. Indeed, this does take us into a > topic of taxonomies vs ontologies. > > If you are seeking a recommendation from TQ on how to model in these > situations, please see the attached Ontologies vs Taxonomies slides. Our > recommendation is to be clear on the distinctions and to maintain these > resources separately. The presentation offers practical advice on how to > organize your models and data using TopBraid EDG. > > -- You received this message because you are subscribed to the Google Groups "TopBraid Suite Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
