Faceted classification Organizing Information Spring 2016 Week 10

Agenda Review basic classification structures Goals of faceted classification Basic design of faceted classifications Facet analysis of complex subjects i.e. factoring Determination of facet structure

Three basic classification structures One hierarchy All concepts emanate via hierarhical relationships from a single root node e.g. the tree of life

Three basic classification structures Multiple parallel hierarchies instead of single root node, there are multiple top-level nodes parallel hierarchies may be of similar kinds but different themes e.g. religion and science, which are both disciplines e.g. Dewey decimal classification

Three basic classification structures Faceted classification A variation of multiple parallel hierarchies Fundamental types are combined to create complex concepts Facets are typically of orthogonal kinds e.g. processes, actors, places See Hunter (real estate) and Vickery for examples

Faceting enables analytico-synthetic classification Faceted classification separates out isolates (or fundamental pieces of a concept) i.e. analysis We combine the isolates into complex subjects when using the classification i.e. synthesis a faceted classification is a systematic set of parts and rules for combining those parts into complex compounds

Structural refinements Basic hierarchical relationships from broader terms to narrower terms is-as, is-a-part-of, is-an-instance-of Additional structural refinements let us clarify relationships between concepts in a single array of terms i.e. at a single level of a hierarchy

Two forms of arrangement within arrays Showing the nature of relationships between narrower concepts to a broader concept Useful when it's necessary to use multiple principles of division Using order of concepts within an array to convey relationships between siblings

Showing principles of division shoes high heels hiking boots mary-janes pumps running shoes sandals slingbacks stilettos wedges winter boots shoes (by season) winter spring (by function) hiking running (by style) boots pumps sandals (by feature) slingbacks mary-janes (by heel type) stilettos wedges (by heel height) high heels and clarify our principles of division at each level.

Clarifying relationships within arrays Furniture (by material) wooden furniture plastic furniture (by style) rococco furniture modern furniture (by room) bedroom furniture office furniture (by function) storage furniture (by form) bookcases tables desks wardrobes bureaus sleeping furniture

Uses of structural labels The parenthetical phrases that indicate principles of division (sometimes called “node labels” or “subfacet indicators”) are typically not used for indexing, they help the user (either the indexer or the information seeker) to understand the types of relationships defined by the system and to apply terms accordingly. A shoe might be indexed as: winter-boots-wedges-high heels. shoes (by season) winter spring (by function) hiking running (by style) boots pumps sandals (by feature) slingbacks mary-janes (by heel type) stilettos wedges (by heel height) high heels

Ordering concepts at each level Possible orders: Chronological (art styles from Post-Impressionist to Dada to Cubist to Abstract Impressionist) Directional (east to west, for example, or closest to farthest) Increasing intensity (slowest to fastest music tempos, for example, or lightest to darkest hues) Increasing concreteness (from more general to more specific, such as from philosophical warrant to cultural warrant to literary warrant) Increasing quantity (from one to many) Order of a process (from plowing to planting to weeding to harvesting, for example)

Ordering example: music tempos Allegro Andante Largo Moderato Presto Vivace (alphabetical) Largo Andante Moderato Allegro Vivace Presto (slowest to fastest)

Taking division seriously Noting ordering and principles of division seem to be edging us closer and closer to facets Because different principles of division often reveal orthogonal characteristics of complex concepts Many classification systems enable some synthetic construction from certain clearly distinguished parts most commonly, place and time

Enumeration works – until it doesn't Consider enumerating all the variations of grape harvesting in all possible times and places grape harvesting in ancient Greece grape harvesting in 19th century Greece ... grape harvesting in Argentina in the 1990s grape harvesting in California in 1970s grape harvesting today in Texas And then what if we want to talk about wheat harvesting, or carrot harvesting, or pecan harvesting

Enter: facets The previous slide shows a kind of coordination of concepts that is very duplicative in its nature We want to think cleverly and systematically about cases like these To separate out the parts so that they are only defined once This is the essence of facets.

Further motivations The sheer number of documents keeps growing The subjects of the documents are both more specific and more complex Knowledge itself is rapidly expanding – new subjects being created It's unlikely to be helpful to enormous numbers of documents into general categories, yet we can't possibly enumberate all the possible subjects that do or will exist

Goals of faceted classification create a classification scheme that lists subject components build complex subjects out of the components as needed facilitate the construction of complex subjects by organizing our classification into facets i.e. potential aspects of the subject

From compound to components a complex subject The history of Japanese tea-drinking etiquette Components (or isolates, or factors) history + Japan + Tea + Drinking + Etiquette Possible fundamental categories (facets): Disciplines (history); Locations (Japan); Beverages (tea); Activities (drinking); Values (etiquette)

Building subjects from components A traditional faceted classification for libraries includes both the facet structure and syntax rules for combining components into complex subjects These rules are necessary to ensure that documents are filed consistently on shelves in online environments this is less of an issue To "mechanize" the subject-building process and simplify filing, components are given a notation that clarifies the components position within a facet

Structure of faceted classifications While a facet may be a simple list, components within a facet are typically arranged hierarchically (using a stricter or looser sense of hierarchy as appropriate). Organic farming classification Crops Processes Materials Fruits (by origin) Planting Natural soil amendments Vines Grapes Controlling pests Compost Bushes Fertilizing Mulch Trees Natural pesticides Vegetables Herbs To create a subject for “Using compost to fertilize grapes” we would combine components from the Crops, Processes, and Materials facets. In an online environment, we would most likely assign each of these concepts as postcoordinate index terms: grapes+ fertilizing + compost. In a physical library environment, we would follow syntax rules to combine the notations for grapes, fertilizing, and compost.

Designing faceted classifications Decompose complex concepts into component parts, via syntactic or semantic factoring Group the simple components into fundamental categories Organize the components in each facet

Understanding complex concepts There are two kinds of compounds: A multi-word unit (which may be a simple concept, such as stained glass, or a complex concept, such as glass cutting). A multi-concept unit (which may be a single word, such as sourdough).

Syntactic and semantic factoring Syntactic factoring A term with multiple words is divided into smaller components e.g. rye bread into rye + bread e.g. Irish emigration into emigration + Irish Semantic factoring A term is divided into multiple elementary concepts e.g. apartment into dwelling + rental + shared building

Semantic factoring Most standards/authorities don’t recommend semantic factoring, and there aren’t rules you can use to help with it. But semantic factoring can sometimes help you discover missing concepts in your subject language. It might be extreme to describe Passover as “holiday + Jewish + commemoration + Exodus,” but doing so might make us consider both religion and commemoration of events as aspects common to many holidays.

Parsing compounds A compound term consists of a focus (the class of things or events) and a difference, which modifies the class and makes a subclass. Examples: Car tires: Focus is tires, difference is cars. Opera singing: Focus is singing, difference is opera. Mushroom hunter: Focus is hunter, difference is mushroom.

Action/patient factoring If the term contains an action (focus) modified by the recipient of the action (difference), factor. But if the term refers to a material (focus) as modified by an action (difference), don’t factor. Example: Hair dyeing: hair + dyeing Bronze engraving: bronze + engraving But don’t factor: dyed hair, engraved bronzes these are kind of like desert soil.

Part/whole factoring If the focus refers to a part or property, and the difference refers to the whole or the possessor of the part or property, factor. But if the focus is the whole, and the difference is the part or property, don’t factor. Examples: Soil acidity: soil + acidity Car tires: tires + cars Don’t factor: spare tires, rain forest. Maybe: pine forest, redwood forest.

Action/performer factoring If the term contains an intransitive action (focus) modified by the performer (difference), factor. If the performer (focus) is modified by its performance of an intransitive action (difference), don’t factor. Examples: Student meeting: students + meetings Lemur migration: lemurs + migrations But don’t factor: migratory birds

Determination of facet structure Ranganathan started from the top down: describing fundamental categories (PMEST) for all subjects and organizing components into those universal facets. The Classification Research Group (CRG), as described by Vickery, advocates beginning from the bottom up reviewing components and assigning preliminary fundamental categories based on the concept’s definition within the classification’s domain, then looking for commonalities in these preliminary choices. Facets in this approach are specific to each classification.

Principles for creating facets Some elements to consider when creating facets: Independence are the facets mutually exclusive? Semantic importance do the facets represent the most important fundamental types in the domain? Balance are the facets at similar levels of abstraction? Comprehensiveness do the facets include all important subject components in the domain? Hospitality would it be easy to add more concepts to a facet? Relevance are the facets of interest to the identified user group and purpose?