- From: Breslin, John <john.breslin@nuigalway.ie>
- Date: Fri, 18 Nov 2011 17:48:56 +0000
- To: <gouadjed@eoweo.com>, <semantic-web@w3.org>
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 17:49:36 UTC