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Well, I hope that folks who care will look at the slides, because the slides say exactly what I said, with phrases like "ensures consistency" and the conclusion that there is no difference between an AP and OWL. And thanks for pointing to the slides -- I hadn't had a link before, and I think they'll be worth quoting in some things I'm working on. kc On 7/27/14, 9:21 AM, Gordon Dunsire wrote: > > Karen > > I agree that the use of "constraint" in RDF and OWL documentation is > misleading - but then that is why the expression of "what we mean" in > RDF is so useful for data and applications in bibliographic > information retrieval services which deal explicitly with the way > humans label things :-) > > I and other members of the FRBR Review Group have read that > documentation, and we hope we have understood it correctly. As far as > I know, we have never claimed that the declaration of property > cardinality constraints, or indeed domains and ranges, is a data > validation technique. > > However, I think the declaration of the intentions of a model, schema, > ontology, or whatever you want to call it, in RDF is highly desirable > as a first step in developing applications for data that purport to > follow the model. That was the context of my presentation in Lisbon > [1][2]. I recall that the dominant topic in the discussion that > followed was the meaning of "constraint" and data validation rather > than the questions I raised in the presentation, so they remain > unanswered :-( > > So I can say that it is the intention of the FRBR Review Group to > express the model using OWL cardinality constraints. The automatic > identification of "sameAs" instances of Works and Manifestations by > reasoners will be useful, for example, in applications that bring > together FRBR-conformant data from multiple local sources. It may well > be useless or harmful to other applications; I think it is up to the > application. I repeat, if there is anything wrong with this, please > (anyone) let us know! > > Is there a specific reason you say "[the "realizes" relationship > between FRBRer:expression and FRBRer:work has owl:qualifiedCardinality > "1"] does not conform, AFAIK, to the E-R analysis in FRBR"? I think it > is fairly clear from the FRBR report containing the results of > applying E-R techniques that "one and only one" is the intended > cardinality between Expression and Work, and Item and Manifestation. > > Cheers > > Gordon > > [1] The FRBR ontology (pptx with animation): > http://www.gordondunsire.com/pubs/pres/FRBROWL.pptx > > [2] The FRBR ontology (pdf with no animation): > http://dcevents.dublincore.org/IntConf/dc-2013/paper/view/139/158 > > *From:*Bibliographic Framework Transition Initiative Forum > [mailto:[log in to unmask]] *On Behalf Of *Karen Coyle > *Sent:* 26 July 2014 23:29 > *To:* [log in to unmask] > *Subject:* Re: [BIBFRAME] BF vocabulary and RDA > > On 7/26/14, 2:27 AM, Gordon Dunsire wrote: > > This is what FRBR actually says: “The methodology used in this > study is based on an entity analysis technique that is used in the > development of conceptual models for relational database systems. > Although the study is not intended to serve directly as a basis > for the design of bibliographic databases, the technique was > chosen as the basis for the methodology because it provides a > structured approach to the analysis of data requirements that > facilitates the processes of definition and delineation that were > set out in the terms of reference for the study.” > > I don’t think that’s quite the same thing. In any case, a > normalized RDBMS is a very good fit indeed with the RDF world; > see, for example, the work of the W3C RDB2RDF Working Group [1]. > > > This is all very complex, and I hardly feel that it can be adequately > covered in an email exchange, nor that I can give the absolute, > definitive answer. It also may be too orthogonal to the concerns of > most people on this list. However, I will try, and welcome others to > weigh in. > > *** > tl;dr: 1) E-R and RDF have some similarities, but are not semantically > the same, especially in how they define "class" 2) OWL is not a > constraint language for instance data, but a language for testing axioms > *** > > First, I'd disagree with "very good fit." In fact, that documentation > says: > > " Is the RDF model an entity-relationship mode? Yes and no. It is > great as a basis for ER-modelling, but because RDF is used for other > things as well, RDF is more general. RDF is a model of entities > (nodes) and relationships. If you are used to the "ER" modelling > system for data, then the RDF model is basically an openning of the ER > model to work on the Web. In typical ER model involved entity types, > and for each entity type there are a set of relationships (slots in > the typical ER diagram). The RDF model is the same, except that > relationships are first class objects: they are identified by a URI, > and so anyone can make one. Furthurmore, the set of slots of an object > is not defined when the class of an object is defined. The Web works > though anyone being (technically) allowed to say anything about > anything. This means that a relationship between two objects may be > stored apart from any other information about the two objects. This is > different from object-oriented systems often used to implement ER > models, which generally assume that information about an object is > stored in an object: the definition of the class of an object defines > the storage implied for its properties. " [1] > > The exceptions noted here are significant. Yes, you can transform an > RDBMS or an E-R model to RDF for the convenience of working within the > RDF world. But note that both RDF and OWL documentation caution > against transferring E-R or OO *concepts* to RDF. To me, the key point > is this: "Furthurmore,[sic] the set of slots of an object is not > defined when the class of an object is defined." The role of classes > in RDF is very different from the role of classes in E-R and OO. That > you CAN transform an RDBMS to RDF does not mean that the same > semantics apply. Caution should be applied, and some adjustments may > need to be made. > > > Karen also said “FRBR has an OWL vocabulary called ‘FRBRer’ that has a > whole host of problems (not the least of which is a fairly deep > misunderstanding of OWL).” I am sure the FRBR Review Group would like > to correct any problems, so it would be useful if you could elaborate > on what the problems are. Also, please let us know what is being > misunderstood about OWL. > > > Gordon, I assumed we had covered this at the DCMI2013 meeting in > Lisbon during the session on application profiles, where it was made > explicit that OWL is not a data validation language, which is why > there is an interest in application profiles that DO provide > constraints. The concept of "constraints" in OWL is not at all > analogous to the concept of constraints in languages like XSD, or in > E-R modeling. In fact, as the OWL documentation says: > > " OWL 2 is not a schema language for syntax conformance. Unlike XML, > OWL 2 does not provide elaborate means to prescribe how a document > should be structured syntactically. In particular, there is no way to > enforce that a certain piece of information (like the social security > number of a person) has to be syntactically present. " [2] > > In other words, 1) classes are not structures in RDF, although they > often perform a structural role in E-R and OO; and 2) OWL axioms do > not and cannot constrain the creation or validation of instance data: > OWL can only infer "truths" from data that exists. (Yes -- see below > -- ICV and others are using OWL with modified semantics to validate > data. Note: "modified semantics.") > > For the latter issue in that previous paragraph, the Open World > Assumption means that if owl:qualifiedCardinality on SSN is "1", and > no SSN is available, this is not an axiomatic inconsistency. In fact, > reasoners do not even note this fact because it is axiomatically > "true". (It's not terribly hard to test this in software like > Protege.) It merely means that the application will assume that there > is an SSN somewhere, just not here, now. If instead the search or > reasoner finds two SSNs, SSN1 and SSN2, it will conclude that > > SSN1 owl:sameAs SSN2 > > That is quite different from how an E-R diagram or an RDBMS interprets > "one and only one." That is because OWL makes use of the non-unique > name assumption - that the same thing can have more than one name > (URI). Note that the same would be true in the use of > owl:qualifiedCardinality in FRBRer [0], where the "realizes" > relationship between FRBRer:expression and FRBRer:work has > owl:qualifiedCardinality "1". Thus, if a FRBRer:expression is a > FRBRer:realizationOf more than one FRBRer:work, those works will be > understood, axiomatically, as being the same work. Therefore, if, in a > particular environment (locally bounded or open on the web), one has > these two statements where owl:qualifiedCardinality for > FRBRer:realizationOf is "1"... > > ResourceB FRBRer:realizationOf ResourceC > ResourceB FRBRer:realizationOf ResourceD > > Regardless of the human-meaningful values of ResourceC and ResourceD, > the inferred meaning is: > > ResourceC owl:sameAs ResourceD > > The identity of ResourceC could be intellectually "Moby Dick" and > Resource D "Little Women." But OWL reasoners will not find an > inconsistency between owl:qualifiedCardinality "1" and more than one > available resource. > > This is not what would result from and entity-relation statement of > "one and only one," and it is quite different from how one might use > cardinality in a *prescriptive* language, like XSD, or in OOP. It does > not conform, AFAIK, to the E-R analysis in FRBR. Nothing about OWL > constrains instance data to conform to what has been defined in OWL, > and OWL reasoners do not return "error messages" for some situations > that would trigger such messages in other languages. At the same time, > some inconsistencies, such as properties that violate disjointness > axioms, can result in the inability of the reasoner to operate at all > on the data. (This depends on the actions programmed into the reasoner.) > > OWL allows inferences on existing data, within the Open World > Assumption and Non-Unique Name assumption. (I wish that OWL > "constraints" had instead been named "axioms" because that is what > they are.) It is for this reason that RDF validation languages, like > SPIN [3], ICV [4], Shape Expression [5], and others are being > investigated in W3C -- because nearly everyone has a need for > validation, and OWL does not provide that. > > How this all relates to FRBRer, RDA and BIBFRAME is quite complex, but > hopefully there will be an article out on this topic before the end of > the year. The upshot is that moving from E-R and OO into RDF requires > some adjustments, both in thinking and modeling. It is also a good > idea to create tests that challenge our "previous software model" > assumptions. > > kc > [0] http://metadataregistry.org/schema/show/id/5.rdf > [1] http://www.w3.org/DesignIssues/RDB-RDF.html > [2] http://www.w3.org/TR/2012/REC-owl2-primer-20121211 > [3] http://spinrdf.org > [4] http://clarkparsia.com/pellet/icv > [5] http://www.w3.org/2013/ShEx/Primer.html > > > > Cheers > > Gordon > > [1] http://www.w3.org/2001/sw/rdb2rdf/ > > *From:*Bibliographic Framework Transition Initiative Forum > [mailto:[log in to unmask]] *On Behalf Of *Karen Coyle > *Sent:* 26 July 2014 02:10 > *To:* [log in to unmask] <mailto:[log in to unmask]> > *Subject:* Re: [BIBFRAME] BF vocabulary and RDA > > On 7/25/14, 4:45 PM, Robert Sanderson wrote: > > While we're piling on... > > On Fri, Jul 25, 2014 at 4:38 PM, Philip Evan Schreur > <[log in to unmask] <mailto:[log in to unmask]>> wrote: > > Structure and data needs come first. Once that's settled, we look > to see how RDA can be expressed in that structure. > > This is exactly it. Bibframe should support RDA, not be > constrained by it. Additional constraints can be layered on top, > for example via profiles. > > > And RDA could be one of those profiles. But *something* has to be the > basis for the underlying data model. I believe that's what FRBR was > trying to be, but unfortunately, FRBR was designed around relational > database concepts and does not fit well into the RDF world. BIBFRAME > has devised its own model, although I'd like to see more discussion of > what that model is trying to represent. (Remember that many people are > not happy at how BF item data is modeled, and the definition of BF > annotation is still quite unclear.) > > RDA has its own RDF vocabulary [1] and may soon have a data creation > platform (at least a beta). (Note that RDA has 1676 properties (!).) > FRBR has an OWL vocabulary called "FRBRer" that has a whole host of > problems (not the least of which is a fairly deep misunderstanding of > OWL). [2] We have no dearth of RDF vocabularies (there's even one for > ISBD), but it's still not clear to me what direction we are going in > or what are the principles guiding the development of BIBFRAME. Not > that I would want to turn BIBFRAME development over to the catechism > that guides IFLA, but, really, what is it that we are doing? > > kc > [1] http://rdaregistry.info/ > [2] http://iflastandards.info/ns/fr/frbr/frbrer/ > > > > Rob > > > > > -- > Karen Coyle > [log in to unmask] <mailto:[log in to unmask]> http://kcoyle.net > m: 1-510-435-8234 > skype: kcoylenet > > > > -- > Karen Coyle > [log in to unmask] <mailto:[log in to unmask]> http://kcoyle.net > m: 1-510-435-8234 > skype: kcoylenet -- Karen Coyle [log in to unmask] http://kcoyle.net m: 1-510-435-8234 skype: kcoylenet