A High-performance Plagiarism Detection System - Notebook for PAN at CLEF 2011

In this paper we report on our high-performance plagiarism detection system which is able to process the PAN plagiarism corpus for the external plagiarism detection task within relatively short timescales in contrast to previously reported state-of-the-art, and still produce a reasonable degree of performance (PAN 11, 4 place, PlagDet=0.2467329, Recall=0.1500480, Precision=0.7106536, Granularity=1.0058894). At the core of our system is a simple method which avoids the use of hash-type approaches, but about which we are unable to disclose too many details due to a patent application in progress. We optimised our performance using the PAN10 collection, and used the best parameters for the final submission. We anticipated a relatively similar performance at PAN11, modulo changes to the plagiarism cases, and 4 place this year put us between participants who had been 5 and 6 in PAN 10.