Software tools to measure the duplication of information

Data stored in average computer system usually is not unique, portions of stored data are duplicated. When duplicated data are stored in separate files containing source code of computer program of student homework, a possibility of cheating should be seriously considered. This paper presents software tools built, in order to detect re-use of pieces of code in supplied text files. Three aspects of information matching are considered: identity, similarity, and analogy. Built tools have proved useful in real life situations.