Indeed, sioc:UserAccount is a subclass of foaf:OnlineAccount, there are thus instances of foaf:OnlineAccount that are not necessarily instances of sioc:UserAccount.
foaf:account has domain foaf:Agent and range foaf:OnlineAccount sioc:account_of has domain sioc:UserAccount and range foaf:Agent According to the OWL reference: "Syntactically, owl:inverseOf is a built-in OWL property with owl:ObjectProperty as its domain and range. An axiom of the form P1 owl:inverseOf P2 asserts that for every pair (x,y) in the property extension of P1, there is a pair (y,x) in the property extension of P2, and vice versa. Thus, owl:inverseOf is a symmetric property." So if there would be a (x,y) for foaf:account, but in which y is not necessarily a sioc:UserAccount and SIOC is used, it would pose a problem because - sioc:account_of is inverse of foaf:account -> so it would contain (y,x) in its population - The domain of sioc:account_of is sioc:UserAccount -> so y must be a sioc:UserAccount - So I would think that a reasoner would deduce that all foaf:OnlineAccounts are also sioc:UserAccounts (which is not the case). This could be solved by removing the domain restriction on sioc:account_of and just use it as the inverse of foaf:account. Best, Christophe ------------------------------------------------------------------------------ CHRISTOPHE DEBRUYNE Semantics Technology & Applications Research Lab Vrije Universiteit Brussel office +32 (0) 2 629 35 40 fax +32 (0) 2 629 38 19 mobile +32 (0) 472 38 71 98 ------------------------------------------------------------------------------ On 8-mrt-2011, at 23:10, John Breslin wrote: > Sorry Christophe, I just found this now, thought it was on the mailing list. > I am copying the mailing list to get other comments. > > I may need you to repeat the question in another way, because I am not sure > if I understand what the issue is - I think we defined sioc:UserAccount to > be a sub-class of foaf:OnlineAccount, > > <owl:Class rdf:about="http://rdfs.org/sioc/ns#UserAccount";> > <rdfs:subClassOf rdf:resource="http://xmlns.com/foaf/0.1/OnlineAccount"/> > ... > > Are you saying that something that has an account_of shouldn't be both an > OnlineAccount and a UserAccount? > > Or rather, we should change the domain of account_of to OnlineAccount > because of the inverseOf property? > > Thanks > > John > > On 22/02/2011 12:37, "Christophe Debruyne" <[email protected]> wrote: > >> Hello, >> >> I'm a bit puzzled by some statements in SIOC while analyzing it for a >> project. >> >> <owl:ObjectProperty rdf:about="http://rdfs.org/sioc/ns#account_of";> >> <rdfs:label xml:lang="en">account of</rdfs:label> >> <rdfs:comment xml:lang="en">Refers to the foaf:Agent or foaf:Person who owns >> this sioc:UserAccount.</rdfs:comment> >> <rdfs:domain rdf:resource="http://rdfs.org/sioc/ns#UserAccount"/> >> <rdfs:range rdf:resource="http://xmlns.com/foaf/0.1/Agent"/> >> <rdfs:isDefinedBy rdf:resource="http://rdfs.org/sioc/ns#"/> >> <owl:inverseOf rdf:resource="http://xmlns.com/foaf/0.1/account"/> >> </owl:ObjectProperty> >> >> - sioc:account_of has domain sioc:UserAccount and range foaf:Agent >> - foaf:account has domain foaf:Agent and range foaf:OnlineAccount >> - yet, sioc:account_of has been defined as the inverse of foaf:account >> >> Isn't this wrong? I'm no expert, but wouldn't a reasoner deduce that all >> foaf:OnlineAccounts are UserAccounts? If not, then it is still conceptually >> wrong. After some searches, I found that Simon Reinhardt asked the same >> question on the google group in January 2009. Both threads (with a couple of >> days in between) didn't receive a clear answer or response. The file that I >> retrieved las week is undergoing regular changes (which can be noticed by the >> couple of "todo" comment statements and the discrepancy between what is >> published in the core specification and the actual ontology. >> >> Could you please provide an answer wether or not this is an issue (and if so, >> when it would be resolved). >> >> Best regards, >> >> Christophe Debruyne >> >> ------------------------------------------------------------------------------ >> CHRISTOPHE DEBRUYNE >> >> Semantics Technology & Applications Research Lab >> Vrije Universiteit Brussel >> >> office +32 (0) 2 629 35 40 >> fax +32 (0) 2 629 38 19 >> mobile +32 (0) 472 38 71 98 >> ------------------------------------------------------------------------------ >> > -- You received this message because you are subscribed to the Google Groups "SIOC-Dev" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/sioc-dev?hl=en.
