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Einst lebte eine Dohle, voll von eitlem Stolz, die stahl sich Federn, die dem Pfau entfallen warn und putzte sich damit. Das eigne Dohlenvolk ver- achtend trat sie in der schönen Pfauen Reihn. Der Unver- schämten reißt man hier die Federn aus, jagt sie mit Schnäbeln. Und die Dohle, bös verbleit will wieder nun betrübt zu ihrem Volk zurück. Die aber stoßen sie von sich, mit herbem Schimpf. Und eine derer, die zuvor verachtet, sprach zu ihr “Hätt’ unsre Lebensart dir vormals conveniert, hätt’st du, was die Natur dir schenkte, akzeptiert, dann wär dir weder jene Schande widerfahrn noch müsstest du zum Unglück jetzt verstoßen sein.”

Diese Version von Aesops Fabel ist aus Wilfried Strohs Sammlung von Übersetzungen von Jan Novák: “Aesopia”, die auf Geschichten von Phaedrus basieren.

C12-02 JPlag

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Software Profile

ID C12-02
Product JPlag
Company Guido Mahlpohl
Web Site
Software Type Online
Costs None
Test Date 2012-02-28


Ranking for all tests: 1
Ranking for Source Code Test: 1
Ranking for Text Test: 4
Summary: useful


JPlag, a system developed at the University of Karlsruhe in Germany, is the winner for recognizing program code collusion and in fourth place for the recognition of textual collusion. The files are uploaded using a Web Start client. It actually compiles the programs, so that it rejects outright any files that do not compile. It accepts programs in Java, C, C++, C#, and Scheme. It will not accept ZIP files, but will work on a directory that has all of the files in it as input. It can also handle nested directories.

One is then directed to an overview page that attempts to quantify the results – the more collusion, the more # are output. Groups of co-similar collusion are grouped together, and the side-by-side presentation makes a comparison easy. The reports are good, although the arrows are not easy to understand at first. But the good use of color makes it easy to see which parts have been copied. However, the reports can only be stored as HTML files, there is no special printing version and we were not able to find a good way of printing them so that an examination board could deal with a case.

It is not quite clear what the difference between the average frequency and the maximum frequency is. But the system was able to deal with renamed variables, insertion and deletion of comments or empty lines, and inserted braces. Code that was moved to another part of the code was only partially recognized.

For the text collusion test it had the problem that it could not handle .doc files, and thus missed quite a number of points for font changes or homoglyphs. Strangely, the first word in the text was never marked, although it was often part of the plagiarism. The system has problems with umlauts, even if German is set as the language. It also only displays a ? instead of the character for other special characters.

In summary, this is the best system to use for finding plagiarism in program code and one of the two system that are determined to be useful for collusion detection.

Company Statement


Screenshot 1: Overview


official website