1. Faceted classification
Organizing Information
Spring 2016
Week 10

2. 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

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

4. 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

5. 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

6. 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

7. 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

8. 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

9. 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.

10. 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

11. 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

12. 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)

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

14. 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

15. 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

16. 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.

17. 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

18. 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

19. 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)

20. 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

21. 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.

22. 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

23. 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).

24. 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

25. 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.

26. 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.

27. 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.

28. 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.

29. 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

30. 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.

31. 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?