Sherlock N-Overlap: normalização invasiva e coeficiente de sobreposição para análise de similaridade entre códigos-fonte em disciplinas de programação

Abstract

This work is contextualized in the problem of plagiarism detection among source codes in programming classes. Despite the wide set of tools available for the detection of plagiarism, only few tools are able to effectively identify all lexical and semantic similarities between pairs of codes, because of the complexity inherent to this type of analysis. Therefore to the problem and the scenario in question, it was made a study about the main approaches discussed in the literature on detecting plagiarism in source code and as a main contribution, conceived to be a relevant tool in the field of laboratory practices. The tool is based on Sherlock algorithm, which has been enhanced as of two perspectives: firstly, with changes in the similarity coefficient used by the algorithm in order to improve its sensitivity for comparison of signatures; secondly, proposing intrusive techniques preprocessing that, besides eliminating irrelevant information, are also able to overemphasize structural aspects of the programming language, or gathering separating strings whose meaning is more significant for the comparison or even eliminating sequences less relevant to highlight other enabling better inference about the degree of similarity. The tool, called Sherlock N-Overlap was subjected to rigorous evaluation methodology, both in simulated scenarios as classes in programming, with results exceeding tools currently highlighted in the literature on plagiarism detection.