Detecting Plagiarism in ICS

Plagiarism is a recognized problem at UCI and nationwide, and our classes in ICS are not immune. To make it as easy as possible for instructors to detect plagiarized solutions to assignments, ICS offers the services described below.

Detecting Plagiarism in Code

To detect plagiarized code, we use the MOSS system. (If you already know you want to use MOSS this quarter, skip to "Getting Started" below). ICS has hired a grad student to handle the logistics--packaging up students' solutions, submitting them for automated examination, reviewing the results, and passing them along to the instructor. We have provided this service for the past five years, and every quarter, it has resulted in the detection of some plagiarized assignments.

Here's a bit of background about the process: There's a long history of automated systems for detecting plagiarized code. They're useful for detecting "equivalence classes" of programs, though of course a trained human eye still needs to review what the system turns up before any accusations are made.

Another characteristic is that these systems don't work well for short, highly constrained solutions. If there's not much room for variation in the first place, similarity may not indicate collusion. Thus, assignments with solutions shorter than about two pages of code aren't usually worth checking with these systems.

The MOSS system runs at Berkeley and is managed by Alex Aiken (who was Alex Nicolau's student). There are details at http://www.cs.berkeley.edu/~aiken/moss.html . It works for programs written in C, C++, Java, Pascal, Ada, ML, Lisp, or Scheme. Its results come back as a web page that highlights suspicious pairs and eases navigation to the similar sections of code. MOSS can also eliminate from consideration common code supplied by the instructor.

Detecting Plagiarism in Prose

Another service, at www.turnitin.com, attempts to identify plagiarism in English prose. UCI has an agreement with Turnitin.com that allows UCI faculty unlimited use of their service. However, this agreement requires that students sign a form with some specific provisions. For details, see the page Turnitin.com in ICS.

Getting Started

If you'd like to try MOSS, just send David Kay (kay@ics) Email listing the assignments you'd like to have checked. For each assignment, please include this information:

• Your name or number for the assignment--however you want us to refer to it (e.g., "HW 3" or "Hashing Lab")


• Where the students' submissions are located (e.g., "under 'Lab 5' in the ICS 22 Dropbox folder on Masterhit on the Windows network," or "in the directory /a/b/c on Igor"). Presuming that each student's submission is distinguishable somehow, we'll collect them into the form MOSS needs.


• The language the solutions are written in (e.g., C++)


• The drop-dead due date--the date after which you don't expect any more submissions (e.g., 4/5/03 midnight)


• Any common code you gave the students--MOSS can take code that the students are supplied with and exclude it from comparisons. Send us the text or a pointer, whichever is most convenient.


• If you have given a similar assignment in previous quarters, you may also give us a pointer to the previous set of solutions (the course, quarter, and assignment name, at least). We will try to locate any archived solutions and include them in the comparison, in an attempt to identify students submitting solutions from a previous offering of the course.

Note that this means we will be accessing the locations you specify. We won't change anything in them--we'll just copy out everything we need. Support will arrange the access, but if this is a problem, let us know.

Also, you might want to mention to your classes that you'll be using a tool that has often detected copied code in the past. This may discourage some improper collaboration, and an ounce of prevention is worth a pound of cure in cheating cases.

Finally, we eagerly solicit any comments, suggestions, or ideas you have on this whole process. Our aim is to make it as convenient and seamless as possible for instructors. (What happens if guilty parties are identified, though, is a subject for another discussion. George Lueker, the ICS Student Affairs office, or David Kay can provide advice on that issue.)