Tags

[edit]

Richard Newman. Tag Ontology Writeup (http://www.holygoat.co.uk/projects/tags/). Retrieved on 2007-05-11 11:18.

Modelling questions

Besides modelling the tagging relationship, modelling tags is itself a challenge. Simple literals are inadequate — e.g., we cannot use them as subjects of triples. Instead, I suggest that tags are modelled through URIs. This seems to agree with some other usages; e.g. WordNet, SKOS, Annotea…?

...

Fundamental design

The fundamental design decisions so far are thus:

1. Taggers are foaf:Agents.

2. Taggings reify the n-ary relationship between a tagger, a tag, a resource, and a date. Relationships exist for each of these roles.

3. Tags are members of a Tag class. Tags have names. We do not attempt to implement plurals (as in the labels schema) or synonymity at this stage, as these are subjective assessments of a tag

[Question: What if I want to remove the agent/tagger from the equation and just have one set of tags used by all users?]

Richard Newman. Tag Ontology Writeup (http://www.holygoat.co.uk/projects/tags/#example). Retrieved on 2007-05-11 11:18.

Using a tag namespace to allow for repeated references to the same tag (not just different tags with the same label):

ex:post tags:taggedWithTag tag:great , tag:interesting .

# Label the tags — once is enough.
tag:great a tags:Tag ;
          tags:tagName "great" .
tag:interesting a tags:Tag ;
                tags:tagName "interesting" .

...

With an identified Tagging event, so we can refer to the event itself in future:

ex:post tags:tag tagging:abcde .
tagging:abcde a tags:Tagging ;
              tags:associatedTag tag:great , 
                                 tag:interesting ;
              tags:taggedBy [ foaf:mbox <mailto:r@example.com> ] ;
              tags:taggedOn "2005-12-03T21:15:00.000Z"^^xsd:dateTime .

Richard Newman. Tag Ontology Writeup (http://www.holygoat.co.uk/projects/tags/#example). Retrieved on 2007-05-11 11:18.

[edit] Relationships between tags

It is desirable to provide some way to interrelate tags; e.g. to describe synonymity, or more human relations like simple association. Of course, these relations are not absolute; stating

tag:ruby :relatedTag tag:gemstone

will be useless or wrong to a significant proportion of users. more accurate is to reify:

_:x      a      :TagRelation ;
  rdf:subject   tag:ruby ;
  rdf:object    tag:programming ;
  rdf:predicate skos:broader ;
  :relater      ex:Richard .
_:y      a      :TagRelation ;
  rdf:subject   tag:ruby ;
  rdf:object    tag:gemstone ;
  rdf:predicate :relatedTag ;
  :relater      ex:John .

These terms are experimental, and there are probably better ways to do this, but you get the idea.

Note, of course, that this vocabulary does nothing to stop you tagging tags…

[edit] What abstract data structure does it (a tag/category hierarchy) look like?

It's sort of like a tree, but since it can have loops, I think it's even more closely represented by a vertex-labeled directed (hierarchy) multigraph/pseudograph. (See http://en.wikipedia.org/wiki/Glossary_of_graph_theory)

Just like how RDF data in general "represents a labeled, directed pseudo-graph"[1].

Or, to put it another way, a collection of tags/categories and their assignments can be represented by a bunch of triples...

article1 hasTag tag1
article7 hasTag tag3
tag1 hasTag tag3
tag2 hasTag tag22