Study of the Wikipedia(en) Categories Graph

Wikipedia is the outstanding project of knowledge accumulation both of general using and different areas of specialization. Quality check of this knowledge, especially automatic, is very important. In this paper, the results of studying a structure of the English version of WCG (Wikipedia Categories Graph) as a whole are presented. The WCG is a system that supports structure of knowledge and it is interesting to know what WCG includes and how it is arranged. It is shown that in graph, there are unacceptable logic violations and organizational and technical methods for elimination are discussed.