faceted_ontologies

Faceted ontologies - definition
This page http://tagunity.wikispaces.com/faceted_ontologies

The term faceted ontology is presented by Patrick Schmitz with regard to his experiments in creating dynamic ontologies from the tags associated with roughly 9 million images uploaded to [|Flickr]™.

Schmitz argues that the user interface (UI) commonly provided as a front end to tagging systems that follow a pure taxonomic model force users to categorise their concepts according to a single closed hierarchy, or vocabulary. Schmitz contends users find such interfaces "awkward, and inflexible," but adds that the drawbacks could easily be overcome through the implementation of "dynamic ontologies and better UI mechanisms," (Schmitz, & Yahoo! Research, 2006, Into. sect.). Schmitz's solution is to induce ontologies from a finite set of tags (i.e. names), and to build a "faceted ontology as a supplement to [the existing Flickr] tagging system, (ibid, Abstract).

Schmitz and his colleagues content: "Tags provide a simple ... mechanism to create annotations that reflect a variety of facets." The aim of their research is to develop "a system that preserve the flexibility of the tagging interface for annotation while also benefiting from the power and utility of a faceted ontology in the search and browse interface," (Schmitz, & Yahoo! Research, 2006, Into. sect.).

What, however, is a faceted ontology? Yannis Tzitzikas provides the following definition: > A faceted ontology is defined by a finite set of facets. Each facet consists of a terminology i.e. a finite set of names or //terms//, structured by a subsumption relation. Each facet is designed separately and it models the domain from a distinct aspect. (Tzitzikas, 2002)

At a conceptual level, faceted ontology is the same as polyhierarchy. That is, sometimes a branch of taxonomy will be permitted to have some terms listed in multiple categories. (As I wrote on the polyhierarchy page includes the example of viral pneumonia, a disease that is both a viral disease and a raspatory tract disease; both viral disease and a raspatory tract disease a sub-classifications of the disease hierarchy, and viral pneumonia is a sub-category of both, [from Morville, 2005 p. 128; see also platypus paradox]).

[todo //define subsumption//]

Schmitz et al. propose that implementation of "subsumption based model" could demonstrate the potential benefits of bringing the "power and utility of a faceted ontology [to the Flickr] search and browse user interface," (2006, Into. sect.), without imposing users the awkwardness or inflexibility they associate with systems that employ closed hierarchical models.

One rationale for Schmitz's research at Yahoo is what he calls tagger's resistance to taxonomies. However, he points to the introduction of bundles by [|Del.icio.us]™, to argue that while "bundles do not support ontological semantics" their introduction Del.icio.us "acknowledges the organisation problems of scaling tagging model," (Schmitz, & Yahoo! Research, 2006, Into. sect.).