Abstract
The study deals with the most important tool of the hierarchical organization of the content of an encyclopedia Wikipedia - its categorial system. The study focuses on the Czech language version of the categorial system, but its results can be generalized to categorial systems of all language versions.
Preliminary studies are devoted to the basic terminology and analysis of important characteristics of the categorial system (universality, hierarchy, heterogeneity, folksonomy, categorization, etc.). The core part is devoted to the analysis and evaluation of solutions to the problems of natural language (synonymy, homonymy, etc.) and issues of logic and appropriateness of the system in general (problems of instability, ambiguity, subjectivity and the resulting inconsistency etc.) and from a user's perspective, too (orientation and navigation within the system).
The final section provides a summary of the earlier parts of the study and final evaluation of the categorial system as a whole.