Content provided in partnership with

Faceted classification and logical division in information retrieval

Library Trends, Wntr, 2004 by Jack Mills

<< Page 1 Continued from page 11. Previous | Next

A further problem exposed by specification is that of dependent concepts. For example, in chemistry, the concept of allotropy might appear in the Properties facet, and by using it as a specifier it could generate the separate class of substances Allotropes. But allotropy is a property special to (dependent on) allotropes and should appear only under allotropes. In BC2, such dependent classes may appear in their basic facet as ghost classes, accompanied by a reference (e.g., Allotropy, see Allotropes). This situation does not occur in the example of (say) an operation like prefabrication; this could be used to specify a number of quite different objects in building technology (e.g., prefabricated bathrooms, as well as prefabricated buildings) and would therefore appear in the Operations facet in its own right.

More Articles of Interest: Classification and categorization: a difference that makes a difference; Knowledge profiling: the basis for knowledge organization; Classification, rhetoric, and the classificatory horizon; Information and its philosophy; The epistemological foundations of knowledge representations

8. EXTRALOGICAL STEPS IN CLASSIFICATION DESIGN

8.1. Citation order (combination order)

Alter logical division, this is the most important feature of a faceted classification. It may be defined as the order in which the characteristics governing division of a class into its facets and arrays are applied. This in turn is reflected in the order in which the constituent terms/concepts (which together summarize the content of a document) appear in an index-description. This is seen most clearly in the rubric (heading) that represents a compound class in a specific alphabetical subject index (see Section 12.2); the designation "specific" here relates to subject headings that seek maximal precision (specificity) in describing a work's subject. Notably, the subject headings in most alphabetical subject catalogs are rarely precise enough to demonstrate this clearly; in a classified catalog, the full rubric for an entry in a medical library catalog (say) might represent a string of terms: Old persons: Bone: Femur: Neck of femur: Fracture: Therapy: Rehabilitation. Usually, in a classified catalog, only the term (s) representing the last steps(s) in the hierarchy are given in the heading, the others being provided for by the headings in the previous steps. The full rubric will appear in the A/Z index to the classified catalog, but in reverse order (see Section 11). Two crucial features of a classification system are largely determined by citation order: First, predictability in locating classes. The citation order decided must be observed consistently if predictability is to be achieved. Clearly, if documents on a disease are sometimes subordinated to the organ affected and sometimes vice-a-versa, the locating of classes becomes unpredictable. Before the appearance of Ranganathan's categories, a measure of consistency was attempted by sets of pragmatic rules, exemplified by Merrill (1939) in his Code for Classifiers. The advent of comprehensive category-based rules has now made such selective rules largely redundant. Second, helpful order: This refers primarily to the helpfulness of the collocations it produces--what is kept together and what is scattered by subordination to other concepts. The number of different ways of classifying a subject is so huge that it would be rash to say that one order is better than all the others. But the one decided upon should be one of which it cannot be said that another is better:

Faceted classification and logical division in information retrieval

Library Trends, Wntr, 2004 by Jack Mills

Find Research Guides for:

Find Featured Titles for: Business

Most Popular Articles in Reference

Most Popular Publications in Reference