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Subject: Re: SV: SV: FW: [plcs-dex] Unique constraints -> identification and versioning
Sean makes a very good point. There's a useful convention for defining classes in an ontology used by some of the Oil and Gas folks that makes Sean's comments explicit: A <class> is a <superclass> that <distinguishing features of this particular subclass>. so in my example you'd have: A SerialNumber is an IdentificationCode that is one of a series assigned for identification which varies from its successor or predecessor by a fixed discrete integer value. I thought this was an excellent convention. Cheers, David On Wednesday 20 December 2006 11:58, Barker, Sean (UK) wrote: > Just to add a further strand to this discussion, Aristotle noted that > definition goes by genus and species, that is, that a definition identifies > what class of thing you are defining (genus), and how it differs from other > things in that class (species). This has two implications. > > Firstly, any single term in a taxonomy is determined by its context, that > is, the full path from the root concept down to the term. In practice, > humans infer the path directly from context, and homonyms do not cause any > particular linguistic community any great problems (although it is a > problem between different communities such as the UK and the US). In an OWL > ontology, this will only cause problems if the reference to the term is > ambiguous because the reference does not define the full context. (PS Tank > is a particularly bad example to choose for homonyms - the term was > originally a cover word from the 1914-18 war to fool the Germans that water > tanks not AFVs were being delivered to the front line.) > > Secondly, and embarrassingly obviously, the most important part of a > classification is the classification criteria, that is, the (real world) > criteria that one uses to decide whether what is falling on my head is fine > rain, drizzle, mist, rain, spitting, heavy rain, a downpour, cats and dogs > or sleet. The concepts are not "out there" waiting to be written down, but > essentially an arbitrary choice of how many terms are needed to divide up > the concept space and where the term boundaries are. The term "essentially > arbitrary" implies that we may choose to make different choices. In > practice, the choices are based on the "forms of life" that we need to > distinguish - in industrial terms, the processes. When, as you were going > out of the door, your mother shouted at you "its raining", this was not a > statement about the amount of water falling from the sky, but an injunction > to put a coat on. > > The idea that concepts are "out there" has been very influential (since at > least Plato's "Republic"), but I suspect is a short cut we use in our > thinking. In practice, the use of a term invokes many connotations - > implied classifications and associations - which is why terminology debates > are so confrontational and tediously long winded as these are teased out. > My biggest concern in this whole discussion is that most of the definitions > are being written using this "out there" thinking, rather than being > explicit on when to use one term or when to use another in the same class. > The danger is that we will produce a standard in geek speak - it works for > the technologist, but not for the user. > > I am now going on holiday until the new year, so merry Christmas and a > happy new year. > > > Sean Barker > 0117 302 8184 > > -----Original Message----- > From: mats.nilsson@fmv.se [mailto:mats.nilsson@fmv.se] > Sent: 20 December 2006 08:43 > To: plcs-dex@lists.oasis-open.org > Subject: SV: SV: SV: FW: [plcs-dex] Unique constraints -> identification > and versioning > > *** WARNING *** > > This mail has originated outside your organization, either from an external > partner or the Global Internet. Keep this in mind if you answer this > message. > > > Hi, > > (See P.S. statement regarding the attachment and my approach to this > discussion) (I've copied the section from David answer below on which I'd > like to comment on) > > > I understand the question now. From what I've seen on the Semantic > > Web, the best practice is to use a (somewhat) human-interpretable > > name for the identifiers of classes in an ontology (within the > > limitations of what you can use in a URL or URI). I agree that the > > use of rdfs:label is the proper way to specify the "name" of the class > > for use in browsers and GUI applications. However, I don't see any > > advantage in not following the Semantic Web practices. I've never really > > understood why anyone would want classes with ids like rd0049404 when > > they can have SerialNumber. > > 1. I'm not sure that the "Semantic Web best practice" is something we > should pay to much attenention to, because imho PLCS Reference Data and > Semantic Web ontologies are not that closely related, even though we use > the same XML application (i.e. OWL) for the representation. > > 2. There will sooner or later be a case when homonyms appear in the same > ontology. For now I have the two examples 'Tank' (container for liquid -or- > combat vehicle) and 'Stone' (a unit of mesure -or- a primitive tool for > emergency repairs). Both these examples are homoonyms likely to appear in > the same domain (even though the 'Stone' example is a bit far-fetched...). > In this case there still has to be a 'Stone(tool)'/'Stone(unit)' notation > in order to separate them. A "meaninless" id string would bo more > efficient. > > 3. You (David) did not comment on the real-world (...FMV...) fact that more > than one word (synonyms) exists as "labels" for the same class. Which one > should be used for the id? The use of the OWL "same_as" construct with > separate classes (with identical definitions) is to me a more complicated > way then using 'rdf:label' for the words and a "meaninless" id string for > the class as a whole. > > 4. In the "interoperability" or "multilingual" oriented world there could > also be a reason to keep the 'rdf:ID'='external_class.id' as a "meaninless" > id string, in order to allow "labels" in different languages and not beeing > forced to use an English word as the identifier... Why not adopt (what I > think is) the eOTD approach. What they do and what we do are quite similar > when it comes to "concept management" (where > concept=id+label(s)+definition). Their "Core Model" (and perhaps the "FMV > concept management information model"... (attached)) might be something to > take a look at. > > I'm glad we got the discussion started! I hope more will join in... > Reference Data is a key aspect to PLCS which in my opinion still is a bit > too loosely defined. > > Regards, > Mats > > P.S. > The attached "FMV concept management information model" is still at a > draft level (and has yet no descriptive text). Its purpose is to be the > base for the definition of an XML based format for the representation of > terminology used within FMV (and in the long run also for the Swedish armed > forces). A project for addressing "concept management" will start at FMV in > january with me as the projet leader. > > In order to be able to classify PLCS data correctly, the classifications > should be based on a defined terminilogy. FMV doesn't have that today. In > order for PLCS to work - this must be established! The aim of the project > is first to create an infrastructure (data format, applications, processes, > information/education and organisation), and then to launch the > organisation and the work of creating a defined terminology. The > infrastructure section of the project should be completed before summer! My > ambition is, as far as it is possible, to use OWL in the same way as the > OASIS PLCS TC specifies its use (something we'll soon have to agree on and > do...) for our (FMV) terminology data format. > > This might explain some of my opinions expressed above and earlier... > > > > > -----Ursprungligt meddelande----- > Från: David Price [mailto:david.price@eurostep.com] > Skickat: den 19 december 2006 17:30 > Till: plcs-dex@lists.oasis-open.org > Ämne: Re: SV: SV: FW: [plcs-dex] Unique constraints -> identification and > versioning > > Hi Mats, See below for two replies. Cheers, David > > On Tuesday 19 December 2006 09:38, mats.nilsson@fmv.se wrote: > > Hi David, > > > > This is one of your examples of a "class.id URI"; > > > > >> urn:iso:std:iso:ts:10303:-1017:ed-1:tech-taxonomy:Part > > > > If I understand you correctly, you suggests to include both the URI > > for the RDL ("urn:iso:std:iso:ts:10303:-1017:ed-1:tech-taxonomy") as > > well as the class identifier ("Part") in the 'external_class.id' (the > > 'id' attribute in the 'external_class' entity). > > > > I thought (see the last of my three slides) > > 'external_class_library.id' was going to be used for the URI of the > > RDL, and that the identifier within the RDL (i.e. 'external_class.id') > > only should contain the actual "classification" or "term" identifier, in > > your example "Part". > > I don't think that works because of the other issues I mentioned (i.e. > there are multiple ontologies involved and one ontology has to be > identified as the context ontology). The context ontology is the most > organization-specific ontology that uses the more general and standard > ontologies. External_class_library is really the only entity type in PLCS > that makes sense for that requirement and so I think there should be one > instance of it that all the External_class entity instances point to > (actually I don't think it's a big problem if there are multiple instances > of External_class_library as long as they all refer to the same URI. So, if > you've followed and agreed with the logic of requiring a context ontology > then I think it's clear that the External_class.id needs to be the full > URI. > > For what it's worth, I think people have been assuming that > "urn:oasis:plcs" was "the reference data library", when in fact in > real-world usage that is unlikely to be the case. The RDL that is the > context for an exchange is actually the ontology developed by the using > organization with its extensions to the PLCS standard classes which is > imported in read-only mode. Because of the flexibility enabled by the use > of the OWL language, it's important to have that context ontology named in > the exchange file. If you look at some of the OWL APIs you'll see that they > often force you to supply an ontology when you'd think only a class is > required as input. That's because the same class can have different > subclasses *and* superclasses (not to mention properties) depending on how > it is extended in using ontologies. > > > Please help me understand if I've got things wrong! If someone else > > has an opinion, please help David help me... > > > > > > Now over to your question David. In my not so organized world (I call > > it > > FMV...) people use more than one term for the same concept > > (concept=class). OWL has the 'rdfs:label' element, which makes it > > possible to assign more than one term for each class. This is useful for > > me because the guys who drive helocopters and those who drive boats often > > have > > different terminology, and I can use this functionality to make them > > understand each other and the data they send. There is also this need to > > be "interoperable" within e.g. the EU Battle Groups or NATO joint > > operations, and then we swedes meet people that uses the word "lubricate" > > for what we call "smörja"... > > > > To accompish this I'd like to use a "meaningless" identifier for the > > 'external_class.id' field, e.g. "rd000453" (or with versioning > > "rd000453v1"), and then use the 'external_class.name' field for the > > readable classification (i.e. one of the available 'rdfs:label's in > > the RDL/OWL-file). > > > > This was what I meant by the question; > > > > >> David: How do you suggest the label used for classification should > > >> be identified in case there are multiple labels for the same > > >> class/RD? > > > > If I have both "lubricate" and "smörja" in the same class (that is a > > subclass of 'activity'/'task') with some unique id, I need to specify > > which one is used. > > > > Clearer? Or don't you see this scenario with synonyms and multiple > > languages (used for the same class/concept)? > > I understand the question now. From what I've seen on the Semantic Web, the > best practice is to use a (somewhat) human-interpretable name for the > identifiers of classes in an ontology (within the limitations of what you > can use in a URL or URI). I agree that the use of rdfs:label is the proper > way to specify the "name" of the class for use in browsers and GUI > applications. However, I don't see any advantage in not following the > Semantic Web practices. I've never really understood why anyone would want > classes with ids like rd0049404 when they can have SerialNumber. The only > rationale I've heard that made any sense to me was related to handling the > uniqueness of ids but since we're engineering the reference data I don't > think the cost in human understandability is outweighed by the small > benefit of slightly easier uniqueness. That said, I also think that the > PLCS RD should be broken up into sub-ontologies on a domain-by-domain basis > for manageability, subsetting and to help with the overloading of terms. > > All that said, I'm not sure that the External_class.name is really useful > for transfering rdfs:label values. I'm not sure of the business need for > that for a start. If the External_class.id is the full URI then that's > sufficient for an application to process. If for some reason the rdfs:label > is needed then I think name_assignment is the only way to handle the fact > that a class may have multiple rdfs:label values for different languages. > However, it seems to me it's better to keep all the labels in the ontology > itself rather than duplicating them in the exchange file. > > > Regards, > > Mats > > > > > > > > -----Ursprungligt meddelande----- > > Från: David Price [mailto:david.price@eurostep.com] > > Skickat: den 18 december 2006 18:05 > > Till: plcs-dex@lists.oasis-open.org > > Ämne: Re: SV: FW: [plcs-dex] Unique constraints -> identification and > > versioning > > > > Hi Mats, a few replies follow (although I'm confused by one question. > > > > On Monday 18 December 2006 07:51, mats.nilsson@fmv.se wrote: > > > Questions below... > > > Happy for opinions! > > > > > > Regards, > > > Mats > > > > > > >> David: Could you please give an example of what an (external) > > > >> class.id URI could look like? > > > > It would be a URN or a URL depending on what organization defines it > > the class and the approach they happen to have adopted. It would be > > the compete URI for the class though it's technically only the > > identifier and so may not be sufficient for location (e.g. if it's a > > URN then some other means would have to be established for an > > application/user to find more info about the class ... for example, an > > organization might have to buy an ISO standard). Examples could be: > > > > urn:iso:std:iso:ts:10303:-1017:ed-1:tech-taxonomy:Part > > > > http://schema.omg.org/spec/UML/2.1/ParameterDirectionKind > > > > http://www.madeupdod.mil/ActivityOntology#Training > > > > > >> David: How do you suggest the label used for classification > > > >> should be identified in case there are multiple labels for the > > > >> same class/RD? > > > > I don't understand what "the label used for classification" means. Can > > you rephrase the question or explain that phrase? > > > > Cheers, > > David > > -- > Mobile +44 7788 561308 > UK +44 2072217307 > Skype +1 336 283 0606 > > > > ******************************************************************** > This email and any attachments are confidential to the intended > recipient and may also be privileged. If you are not the intended > recipient please delete it from your system and notify the sender. > You should not copy it or use it for any purpose nor disclose or > distribute its contents to any other person. > ******************************************************************** -- Mobile +44 7788 561308 UK +44 2072217307 Skype +1 336 283 0606
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