Explanation in Code Similarity Investigation

When using code similarity detection to uncover code plagiarism and collusion, the marker needs to determine whether any detected similarities might be the result of coincidence. But understanding the similarities can be difficult and might be prone to human error, because few tools facilitate the investigation process, and if they do, the similarities are not explicitly explained in human language. This paper presents STRANGE, an investigation module that exclusively explains code similarities in natural language (English and Indonesian). For the purpose of reusability, STRANGE can be embedded in JPlag and other code similarity detection tools. It can also act as a standalone tool for measuring source code similarity. Our evaluation shows that STRANGE is more helpful than JPlag in the investigation process since it explains the similarities in natural language. Further, its effectiveness is comparable to that of JPlag but higher on trivial disguises of the sort that novice students will tend to apply when disguising copied code.