[rdfweb-dev] FOAF without email/sha?

Christopher Schmidt crschmidt at crschmidt.net
Thu Apr 7 12:36:53 UTC 2005

On Thu, Apr 07, 2005 at 04:28:53AM +0700, Hendy Irawan wrote:
> Hi!
> Is it possible to "foaf" a person that doesn't even have an e-mail
> (like, say, Jean-Paul Sartre?)? let alone sha1mbox...

There are a number of unique identifiers which function equally well for
FOAF: Anything which is declared as an owl:InverseFunctionalProperty can
be used for this purpose. Julie says that these are:

foaf:msnChatID, foaf:dnaChecksum, foaf:mbox_sha1sum, foaf:weblog,
foaf:jabberID, foaf:mbox, foaf:icqChatID, foaf:homepage, 
foaf:aimChatID, foaf:yahooChatID

foaf:homepage would probably be the best case for this one, however,
there are cases where you can't even do that. In these cases it is, as
you say, very difficult to match these people up.

However, I can't really think of a decent solution to this. If you don't
have any uniquely identifying information that you're willing to reveal
about the person, there's no way to match them up. 

In your "mother" example, later in thread, you might be able to do
something with the rel schema, saying that if someone rel:hasMother foo,
and foo is named bar... eh, what if you've got a mom and stepmom with
the same name. You're still not uniquely identifying them.

Without something that's specific to that person, you're going to have
to fall back to reasoning to figure out answers you're looking for, and
even then you're going to be dealing in probabilities: my mother has
brown hair and brown eyes, and $person2 has a mother with brown hair and
brown eyes, and Person2 and I both have the same AIM name: what is the
probability that the mother in question is the same person?

I think if you have any unique information you want to reveal, you can
either find a schema which declares the prop you want to use as an
owl:IFP, or you can create such a schema yourself. In that case, any
unique information can be used to match people, but without unique
information, you're kind of SOL (other than creating a URI or mbox or
something similar for them).

In many cases, however, it won't really matter if you're talking about
the same person or not: for example, when querying against my RDF store,
any results which are the same are just displayed with a multiplier. If
you're asking "What is the name of Henry James", even if she can't be
smushed, so there are two people, you can still see the name.

This has gotten long and rambly, so I'll cut it off. Just some thoughts.

Christopher Schmidt
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