Batch source-code plagiarism detection using an algorithm for the bounded longest common subsequence problem

Abstract

Source-code plagiarism detection is an unfortunate but necessary activity when reviewing assignments of programming courses. While being reasonably easy to fool, string-based comparisons offer a high degree of accuracy with almost no false positives and usually a good string similarity metric is the length of their longest common subsequence. In the case of two strings, the dynamic programming algorithm for this calculation unfortunately takes quadratic time even if the strings are equal. In this paper we present an algorithm that, given a batch of source-code files, efficiently finds all pairs of similar files by preprocessing the files and then using a fast branch-and-bound algorithm to find only those pairs whose longest common subsequence is indicative of plagiarism.

PDLK: Plagiarism detection using linguistic knowledge

“…Winnowing algorithm (Schleimer, Wilkerson, & Aiken, 2003) is employed reduce the number of terms in order to accelerate the detection process. LCS is used to compare two strings and to find out the longest overlapping path (Campos & Martinez, 2012;Iliopoulos & Rahman, 2009). The result shows that reducing non-relevant document shortens the processing time compared to non-reduced process.…”

Model Checking for String Problems

“…the shortest common superstring. Such problems have important applications in bio-informatics as in sequence and genome analysis [12,22], in linguistic information retrieval [24]; plagiarism detection, for instance in publications [11] or source code [17,5]; data compression [21] and so on.…”

Recognition of the Ambulance Siren Sound in Taiwan by the Longest Common Subsequence

“…The Longest Common Subsequence (LCS) is a well known scoring-based method [15,16,17] and it is widely applied in pattern recognition such as hand gesture recognition [18], music matching [19], DNA sequence clustering [20] and code detection [21]. LCS is the comparison between different sequences to identify the longest subsequence structure which all the sequences contain.…”