sioc:User vs. foaf:Person

[CaptSolo]

Hi, all! :)

Thanks to Alistair, Dan and Libby who, while at ISWC-2005,
participated in a meeting about the development of the SIOC ontology
[1] and aligning it with FOAF and SKOS.

I have done an initial update of the SIOC specification [2] as agreed
in the meeting by:
- introducing a new subclass relationship between sioc:User and
foaf:OnlineAccount
- deleting old mappings of sioc:User to foaf:Person; and
sioc:Usergroup to foaf:Group

SIOC User now is an online account that a person has created on an
online community site. A person that has an account is linked to it
via the foaf:holdsAccount property. This way we can separately
describe each online community account that a person has, avoiding
unwanted "smuching" of all accounts together.

The ontology namespace, the mappings and the specification were
changed accordingly (see sioc:User and sioc:Usergroup). [See
http://rdfs.org/2005/11/sioc-foaf.jpg for a draft scheme of changes].

Next things to do:
- remove the properties that describe the a rather than an account
from SIOC [and use FOAF to describe them]
- in FOAF an inverse property of foaf:holdsAccount is needed to point
to the person who holds the account

Removing properties should be done with caution though, e.g.:
- sioc:knows looks redundant, but if we remove it how will we be able
to indicate the fact that the "knows" relation exists between two
accounts on a particular community site?
- sioc:email and sioc:email_sha1 seem redundant, but again - how do we
link the sioc:User account to the particular e-mail address that the
user used to register on this site (e.g., we will need this if we want
to "export" sioc:User from one site and "import" into another
community site)

Future - decide on other issues discussed at the meeting:
- (1) how to model relations between the foaf:Person, sioc:User and
sioc:Post one has created taking into account that foaf:OnlineAccount
is not a foaf:Agent and hence by definition can not be a foaf:Maker of
a sioc:Post [see http://rdfs.org/2005/11/sioc-user_account.jpg for 2
alternatives discussed];
- (2) what properties to use with SKOS to indicate the topic of
sioc:Posts [see http://rdfs.org/2005/11/sioc-topic.jpg].

Your comments are very welcome and I'd be glad if those who were at
the meeting would also comment and add to the information written
here.

[1] http://rdfs.org/sioc/
[2] http://rdfs.org/sioc/spec/

At the meeting: http://www.flickr.com/photos/captsolo/65680467/

Best,
Uldis

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