Need to categorize: A comparative look at the categories of the Universal Decimal Classification system (UDC) and Wikipedia

This study analyzes the differences between the category structure of the Universal Decimal Classification (UDC) system (which is one of the widely used library classification systems in Europe) and Wikipedia. In particular, we compare the emerging structure of category-links to the structure of classes in the UDC. With this comparison we would like to scrutinize the question of how do knowledge maps of the same domain differ when they are created socially (i.e. Wikipedia) as opposed to when they are created formally (UDC) using classification theory. As a case study, we focus on the category of “Arts”. In modern times, the fast expansion of human knowledge makes categories a necessity in managing and accessing produced knowledge. The science of ‘knowledge orders’, i.e. taxonomies, classifications, etc., is born out of this need. However today, with all the tools the information society has to offer, taxonomies have a powerful opponent: folksonomies. Folksonomies are an outcome of the phenomenon of collective writing, and collaborative tagging. Wikipedia is one favorite object for studying such behavior. For a long time, Wikipedia relied only on search engines for information retrieval, and its users browsed the content by following simple links (called page-links) between Wikipedia articles. Only in 2004, after four years of its publication, Wikipedia introduced the concept of categories for the use of its authors. However, what the Wikipedians did by assigning categories to articles, and linking categories to each other, is closer to folksonomies then taxonomies. Traditionally, classification of knowledge is a task handled by experts, resulting into a designed system of organization. In contrast to this, the category system in Wikipedia is atypical, as it was not designed by experts, but created through the initiatives of individual Wikipedia authors. In this study, we compare the category of Arts from Wikipedia to the main table of Art in the Universal Decimal Classification system. Our goal in this comparison is to address how domains mapped by classification theory differ from socially-mapped domains.