Optimal User-Centered Knowledge Organization and Classification Systems: Using Non-reflected Gray Codes
Existing library classification systems, such as the Dewey Decimal Classification (DDC) system and the Library of Congress Classification system, are generally considered effective at bringing similar documents together. For example, the DDC system is widely used to classify books in libraries and increasingly is being used for online applications, such as browsing Online Public Access Catalogues (OPACs) and Cooperative Online Resource Catalogs (CORCs), and will probably see increasing use in digital libraries. Based on theoretical considerations, a classification system consistent with the Gray code provides an optimal organizing principle for documents; it can be used to classify knowledge, as can the classification systems commonly used in both paper and digital libraries. What is the relationship between a theoretically optimal Gray code-based classification system and the existing classification systems? We suggest that the non-reflected Gray code provides a basis for ordering documents that is more consistent with existing classification systems than is the more frequently discussed reflected Gray code. This provides both a theoretical basis for existing techniques and a standard by which document organizing systems in digital libraries may be compared, evaluated and improved.