PASCAL - Pattern Analysis, Statistical Modelling and Computational Learning

Intrinsic plagiarism detection using character trigram distance scores
Mike Kestemont, Kim Luyckx and Walter Daelemans
In: PAN at CLEF 2011, 21-22 Sep 2011, Amsterdam, The Netherlands.


In this paper, we describe a novel approach to intrinsic plagiarism detection. Each suspicious document is divided into a series of consecutive, potentially overlapping ‘windows’ of equal size. These are represented by vectors containing the relative frequencies of a predetermined set of high-frequency character trigrams. Subsequently, a distance matrix is set up in which each of the document’s windows is compared to each other window. The distance measure used is a symmetric adaptation of the normalized distance (nd1) proposed by Stamatatos [17]. Finally, an algorithm for outlier detection in multivariate data (based on Principal Components Analysis) is applied to the distance matrix in order to detect plagiarized sections. In the PAN-PC-2011 competition, this system (second place) achieved a competitive recall (.4279) but only reached a plagdet of .1679 due to a disappointing precision (.1075).

PDF - Requires Adobe Acrobat Reader or other PDF viewer.
EPrint Type:Conference or Workshop Item (Paper)
Project Keyword:Project Keyword UNSPECIFIED
Subjects:Computational, Information-Theoretic Learning with Statistics
Learning/Statistics & Optimisation
Natural Language Processing
ID Code:8688
Deposited By:Kim Luyckx
Deposited On:19 February 2012