The software and text similarity tester SIM

SIM tests lexical similarity in texts in C, Java, Pascal, Modula-2, Lisp,
Miranda, and natural language.  It is used

- to detect potentially duplicated code fragments in large software projects,
	in program text but also in shell scripts and documentation;
- to detect plagiarism in software projects, educational and otherwise.

SIM is available through ftp.  The directory

	ftp.cs.vu.nl:pub/dick/similarity_tester

contains the sources (in C) and the MSDOS .EXEs.

The software similarity tester is very efficient and allows us to compare
this year's students' work with that collected from many past years (much to
the dismay of some, mostly non-CS, students).  Students are told in advance
that their work is going to be compared, but some are non-believers ...

The output of the similarity tester can be processed by a number of shell
scripts by Matty Huntjens.  These shell scripts take sim output and produce
lists of suspect submissions, histograms and the like.
The present version of these scripts is very much geared to the local situation
at the Vrije Universiteit, though; they are low on portability.
Matty Huntjens' email address is matty@cs.vu.nl.

We are not afraid that students would try to tune their work to the
similarity tester.  We reckon if they can do that they can also do the
exercise.

Since this piece of handicraft does not qualify as research, there are no
international papers on it.  A paper, titled `Detecting copied submissions in
computer science lab work', was published in a local (i.e. Dutch) computer
science journal:

%A Dick Grune
%A Matty Huntjens
%T Het detecteren van kopie\(:en bij informatica-practica
%J Informatie (in Dutch)
%V 31
%N 11
%D Nov 1989
%P 864-867

The ftp directory contains a terse technical report about the internal
working of the program.

					Dick Grune
					Vrije Universiteit
					de Boelelaan 1081
					1081 HV  Amsterdam
					the Netherlands
					dick@cs.vu.nl
					+31 20 444 7744
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