1. Structuring Classifications
Organizing Information
Spring 2016

2. Classification structures
Three primary types
Single hierarchy
Multiple hierarchy
Faceted Classification

3. Classification structures
Single hierarchy:
all terms are related to one top term, or root node
e.g. in a biological taxonomy of species, the root node would be “living organisms” and proceed from there.

4. Classification structures
Multiple hierarchies:
multiple top terms are employed to represent different kinds or thematic areas
e.g. the gene ontology has three different subontologies for cell components, biological processes, and metabolic functions,
e.g. the Dewey Decimal classification has ten (it’s decimal!) top terms for broad disciplinary divisions, including Social Science, Science, Religion, and Arts and Recreation.

5. Classification structures
Faceted classification:
multiple top terms indicate different component types, or facets, that are combined to make synthetic classes.
The component facets usually represent fundamental types (like space, time, substances, processes, roles) and not concept areas (like intellectual property or labor rights).
Terms within a facet may be themselves arranged in hierarchies; a faceted classification appears similar to one with multiple hierarchies.
The difference is that facets are meant to be orthogonal—independent of each other
not like Science and Social Science in the Dewey Decimal Classification, which are both disciplines,
but like Products [e.g., bread or furniture] and Processes [like baking or carpentry], which are of different kinds

6. Classificatory relationships
Hierarchical relationships involve three primary types
Genus to species
Part to whole
Type to instance

7. Classificatory relationships
Genus to species, or broader to narrower:
the _IsA relationship.
A dog (narrower) is_a canine (broader).
Strict hierarchies demonstrate inheritance of characteristics down the tree.
A canine (narrower) is a mammal (broader);
therefore, what is true about mammals will be true for dogs as well.
e.g., they are warm-blooded, they are hairy, they

8. Classificatory relationships
The tree relationship described by Kwasnik does not include strict inheritance; what’s true of a general is not necessarily true of a private.
However, the relationship from general to colonel all the way down to private is consistently maintained: colonels are lesser rank than generals who are lesser rank than majors, and so on.

9. Classificatory relationships
Part to whole.
A steering wheel is part of a car
a nucleus is part of a cell.

10. Classificatory relationships
Type to instance:
The Mediterranean is an instance of a sea
The Mediterranean is not part of a sea
nor is it a kind of sea;
it is a specific sea.
Texas is an instance of a state.
Texas is not part of a state,
nor is it a kind of state;
it is a specific state.
Distinct from parthood and is_A
A county is part of a state
Travis County is an instance of a county
a state without income tax is a kind of state.

11. Example
Furniture
Holds people
Holds stuff
The principle of division is what is being held; people or stuff.
According to this hierarchy, all furniture either holds people or stuff; it doesn’t (primarily) hold both.

12. Example
Animals
Uses for products
Uses for services
The principle of division is the nature of the use of an animal by humans
I may want to revise my label to "Human uses of animals" to clarify this

13. Back to the furniture Furniture
Holds people
Furniture people sit on
Furniture multiple people sit on
Furniture one person sits on
Furniture people lie on
Holds stuff
The principles of division here are the posture assumed by people using the furniture, and the number of people who can use it at once.

14. Sticking to a principle of division
Furniture
Wooden furniture
Modern furniture
Bedroom furniture
Bookcases
Mixing principles of division at a single level of a hierarchy makes the relationships between broader and narrower terms confusing and potentially overlapping, because different perspectives are being employed at once.

15. Clarifying prinicple of division
One way to improve this is to make the principles of division clear by adding “node labels”:
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

16. Consistent level of abstraction
Note another problem with #4: “Bookcases” was at a lower level of abstraction than the other terms.
In general, all terms at the same level of a hierarchy should be at a similar level of abstraction, and there should be consistent degrees between levels
that is, not extensive jumps from very general to very specific, like from fruit to Jazz apple, or vegetable to hen-of-the-woods mushroom.

17. Arrangement within arrays
The set of terms at a single level of hierarchy is called an array.  
The order within arrays is another means of conveying information
ideally the order should be purposeful
that is, not just alphabetical by label.

18. Arrangement within arrays
Possible orders within array include:
Chronological
e.g. art styles from Post-Impressionist to Dada to Cubist to Abstract Impressionist
Directional
e.g. east to west, e.g. closest to farthest
Increasing intensity
e.g. slowest to fastest music tempos
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
e.g. from one to many
Order of a process
from plowing to planting to weeding to harvesting, for example

19. Tips Sort like with like.
Try to place like kinds of things together (processes, products, people),
not just things that have some thematic relation.
A hierarchy in its strict form takes one kind of thing and goes from the most general category to the most specific.

20. Example
this: Animals è domesticated animals è animals raised for food è pigs
this: Agricultural processes è farming è factory farming
this: Effects è effects of farming practices è effects on animals è overcrowding
not this: Animalsèpastures, pens, cages è overcrowding
not this: Animals èfactory farming è mercury poisoning

21. Tips
You may need to generate intermediate levels that weren’t explicit in your source concepts.

22. Example
Source concepts: meat eating, e.coli, cholesterol, sustainability 
Hierarchical structure that relates these source concepts:
disadvantages of meat eating
health risks
health risks associated with meat eating
high cholesterol
health risks associated with industrial meat production
bacterial contamination
e.coli contamination
unsustainable practices
effects of industrial meat production
consumption of resources
pollution