This paper details a novel algorithm for comparison of suspect documents at a sentence level and has been implemented as a component of plagiarism detection software for detecting similarities in both natural language documents and comments within program source-code.

http://doi.acm.org/10.1145/1086339.1086341

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It could be useful to implement a plagiarism detection system for conference papers. ;-) I remember we use to manually find copied papers on the net during Vidyakash 2002/KBCS 2002 conferences.