- From: Ghalem Ouadjed (EOWEO) <gouadjed@eoweo.com>
- Date: Fri, 18 Nov 2011 19:47:48 +0100
- To: "Breslin, John" <john.breslin@nuigalway.ie>
- CC: semantic-web@w3.org
Hi John, that could be nice for some aspects but what about A friend of B A friend of C and B friend of C exists Cheers Ghalem Le 18/11/2011 18:48, Breslin, John a écrit : > How about applying the number of contacts to an account rather than a person? That way you could assume num_contacts or num_followers is known... for the site the account is on. > > We have properties in SIOC like num_replies and num_views for content items. > > John > http://bresl.in > > On 18 Nov 2011, at 17:24, "Ghalem Ouadjed (EOWEO)"<gouadjed@eoweo.com> wrote: > >> >> Le 18/11/2011 16:48, Paul Gearon a écrit : >>> Hi Heiko, >>> >>> On Fri, Nov 18, 2011 at 4:33 AM, Heiko Paulheim >>> <paulheim@ke.tu-darmstadt.de> wrote: >>>> Due to the open world assumption, the value of that counter would (probably) >>>> we wrong. >>>> >>>> If I have >>>> :Peter foaf:knows :Stephen . >>>> :Peter foaf:knows :Marc . >>>> >>>> and, based on that knowledge, I added >>>> >>>> :Peter myschema:friendnb "2"^^xsd:integer . >>>> >>>> this would not be a valid conclusion - there may be a lot more friends of >>>> Peter which are not in my knowledge base (don't we all have friends without >>>> a facebook account?), and :Stephen and :Marc might even refer to the same >>>> person. In other words, with that approach, I would add knowledge to my >>>> knowledge base which is potentially wrong. >>> While you are correct in saying that the inference of 2 friends is >>> invalid, the idea of cardinality is not inconsistent with the open >>> world assumption (OWA). Melvin's original question was about a >>> property that can be used to declare cardinality, and this is fine >>> with the OWA. Indeed, OWL uses it. >>> >>> So, for instance, if you declare: >>> >>> :Peter myschema:friendnb "2"^^xsd:integer . >>> >>> and then you say: >>> >>> :Peter foaf:knows :Stephen . >>> :Peter foaf:knows :Marc . >>> :Stephen owl:differentFrom :Marc . >>> >>> Then you know that we have identified all the friends of :Peter. This >>> does not preclude another statement of the form: >>> >>> :Peter foaf:knows :Steve . >>> >>> But since we already knew all of :Peter's friends, then we know that >>> this new statement must refer to an alias for one of the existing >>> friends. >>> >>> Taking it further: >>> >>> :Steve owl:differentFrom :Marc . >>> >>> Means that: >>> >>> :Steve owl:sameAs :Stephen . >>> >>> All of this is just a long-winded way of explaining that a cardinality >>> predicate is not in conflict with the open world assumption. However, >>> it works with different use cases than with the closed world. >>> Specifically, under the OWA you cannot derive the current cardinality, >>> but you can declare it. >>> >>> Regards, >>> Paul Gearon >>> >> So i could have an "Owner" (of an account) class and a "Friends" class which are subclasses of an union of both >> and an inverse hasFriends - isFriendOf and a value restrictions right? >> >> Cheers >> Ghalem >>
Received on Friday, 18 November 2011 18:48:27 UTC