Reply #1: not a librarian, but

[mzteris]

a couple of different links to places for bits and pieces of info.

I'm not positive I know what you want to know.

I'm not positive that what I think you want to know is out there.

I think, maybe, if you read through some of these - plus maybe search for some others - you might ferret it out, or - rather - find enough information to figure out what you want to know.

*****

"(Soergel) wrote a great paper difference between a taxonomy and an ontology. Essentially, a standard taxonomy/thesaurus/controlled vocabulary has only three relationships, "broader term", "narrower term," and "related term." An ontology has a mess of sematic relationships between terms.

In a taxonomy, for example, you could have:

Dogs
Related term: Housepets
Narrower term: puppies, border collies, Fido
Broader term: Housepets


An ontology could add a-whole-nother layer of meaning on top of this. You could have:

Dogs
LivesIn: House
Chases: Cats
CrapsOn: Carpeting

A taxonomy is just a classification of things. They are usually hierarchical. They do two things: give exact names for everything you're dealing with (your 'domain') and show which things are parts of other things (sometimes called parent-child relationships, sometimes called broader-narrower).

An ontology is like a taxonomy in that it is going to contain all the entities in your domain (for one reason or another--probably its roots in philosophy--people often seem to use the term "universe" when talking about the domain of an ontology), and show the relationships they have to each other. However, it does more: it has strict, formal rules (a "grammar") about those relationships that let you make meaningful, precise statements about your entities/relationships.

When I think of an ontology, I think of putting the universe in a bottle. It's a very ambitious thing to do. If you have a proper ontology worked out, it means you know everything about everything. In general, the more useful an ontology would be, the closer to impossible it's going to be to make it.
http://ask.metafilter.com/29264/Are-the-terms-ontology-taxonomy-and-folksonomy-interchangeable

*****

faceted classification, one of the most powerful, yet least understood, methods of organizing information. Most folks, when thinking about organizing objects or information, immediately think of a hierarchical, or taxonomic, organization; a top-down structure, where you start with a number of broad categories that get ever more detailed, until you arrive at the object. In such structures, each object has a single home, and typically, one path to get there--this is how things are organized in "the real world", where each item can only be in one place. Oftentimes, when thinking of organizing information, a hierarchy is where people begin (think Yahoo!).

Faceted classification, on the other hand, is a bottom-up scheme. Here, each object is tagged with a certain set of attributes and values (these are the facets), and the organization of these objects emerges from this classification, and how a user chooses to access them. Toys, for example, lend themselves to a faceted classification, with the facets being things like, "Suitable Age," "Price," "Subject Type," "Brand," and even "Character" (like Barbie or Elmo). Someone might be price conscious, and want to start there; another knows that the child in question loves science toys, and wants to begin with that. Faceted classification allows for exploration directed by the user, where a large dataset is progressively filtered through the user's various choices, until arriving at a manageable set that meet the users' basic criteria. Instead of sifting through a pre-determined hierarchy, the items are organized on-the-fly, based on their inherent qualities.

Now, faceted classification isn't inherently innovative. In fact, objects tend to have a fixed set of facets by which they are organized. Where innovation comes is through user research that listens to how the users/customers/audience think about and approach a task, and providing tools to allow them to approach it meaningfully.

. . . MORE . . .

http://www.peterme.com/archives/00000063.html