Systems for checing electronic texts

The work deals with the possibility of control of electronic texts. Whether it is a source codes or standard text documents. The first chapter is devoted to a brief explanation of the term plagiarism and its characters. Sequentially we describe the methods and metrics used to detect plagiarist. Then we pay attention to detect plagiarism in the free text and source codes. We describe the way of preprocessing of a file and choice of basic units, which represent the document in the comparing. Source codes have a exact syntax. Therefore we attend to the syntax and semantic analysis in the chapter, which describes the check of source codes. The second half of the work is focused on the practical part, particularly on programs intended to control the source codes. The programs are divided to the freely available and the commercial. This is followed by their brief description and if it is a free trial possible we mention the results from this comparing. So we created a corpus of source codes. At the end of the work we focus on design of a program, which compares two source codes on the basis of statistical similarities