  Plagiarism detection in educational programming assignments is still a
problematic issue in terms of resource waste, ethical controversy, legal risks,
and technical complexity. This paper presents AC, a modular plagiarism
detection system. The design is portable across platforms and assignment
formats and provides easy extraction into the internal assignment
representation. Multiple similarity measures have been incorporated, both
existing and newly-developed. Statistical analysis and several graphical
visualizations aid in the interpretation of analysis results. The system has
been evaluated with a survey that encompasses several academic semesters of use
at the authors' institution.
