Cheating Detector from Georgia Tech 941
brightboy writes "According to this Yahoo! News article, Georgia Tech has developed and implemented a "cheating detector"; that is, a program which compares students' coding assignments to each other and detects exact matches. This was used for two undergraduate classes: "Introduction to Computing" (required for any student in the College of Computing) and "Object Oriented Programming" (required for Computer Science majors)." Cuz
remember programmers: in the real world you are fired if you consult
with a co-worker ;)
You're caught (Score:5, Funny)
Re:You're caught (Score:5, Insightful)
Students shouldn't cheat, but professors shouldn't toss around those accusations lightly either.
Re:You're caught (Score:5, Insightful)
I don't claim to be a model student by any means, but in this class of 16 I had the highest grade in the class and had done every assignment to the best of my abilities. It came as quite a shock to me when I got my grades and noticed that there was an F for my Programming Languages class.
I promptly called the professor and he said that this was an issue that was best dealt with in a face to face manner - so I went to his office and he claimed that myself and 3 other students in the class had cheated. He pulled up the source code and showed the very striking similarities. When I explained him that some of the problems that were assigned were out of the scope of this class and that he offered no help, I informed him that I had worked with these students to get a solution to the problem. We did not copy any prior works, and all worked together to complete a tough assignment. I admitted that we shared code, only because we had shared ideas and had all come to the solution together.
To make an already long story short (Im forcing myself to leave out details), it ended up getting appealed and overturned, and the professor is now on probation and only teaching 100 level courses
The moral - cheating and sharing of ideas are different concepts and should be handled seperately. I don't agree with programs that flag cheating based on similarities in code because sharing of ideas is typically encouraged in a university setting as long as they are obtained legitimately - a program as such cannot sufficiently distinguish the two.
Re:You're caught (Score:4, Informative)
Re:You're caught (Score:3, Insightful)
I had a student turn in a copy of my own solution, including all my idiosyncratic assumptions, like assuming exactly the same number of blades of grass per cm2, and assuming the same (wrong) width I had guessed for the field.
Sorry, but I have to say this is your fault for setting exactly the same question. If I have to solve a problem when I have already seen a solution, I am going to come up with something very similar even without intentionally cheating. This doesn't excuse an exact copy, but how do you expect students to think about a problem and come up with their own solution when they have already seen it done?
Re:Talk about cheating (Score:3, Interesting)
Of course, he was also aware of the limitations of the program (given that he wrote it), so I don't believe that he took the statistics as the sole sole arbitrator of whether or not students were stealing code.
On the other end of the scale, Dan once found out that someone had published a solution to one of his assignments. He publicly announded in class that he was aware of the cheat. For anybody who had already submitted copied code and couldn't come up with a 'real' solution, he offered a partial amnesty (a zero on the assignment, but otherwise no punnishment) for people who came forward and fessed. He also warned that anybody trying to sneak the cheat past him would be failed from the course.
Despite his warning, a number of students still submitted the known cheat. Some blindly submitted the file without any edits whatsoever -- not even bothering to fix a simple syntax error that kept the program from compiling. As promised, they were removed from the course and reported for cheating.
There's no accounting for abject stupidity.
In the real world... (Score:2, Insightful)
If your employer has any integrity at all, that is.
Re:In the real world... (Score:2, Funny)
This is bad (Score:2, Funny)
Real-world vs. school (Score:4, Insightful)
Yes, but one of the goals of a CS department should be to produce programmers who are capable of doing work themselves. Would you want to work with (or supervise) a slacker who couldn't code his way out of a paper bag, but who graduated anyway because he cut-and-pasted the work of his (harder-working) classmates?
Re:Real-world vs. school (Score:3, Insightful)
Anyhow, the employment market will vet real workers from pretend ones. I think the motivation in this case, from the universities perspective, is to not have their degree and academic rep devalued. Obviously, the better the grads, the more money and brains go into the school
Re:Real-world vs. school (Score:5, Insightful)
Slashdot should learn something... (Score:3, Funny)
http://slashdot.org/article.pl?sid=01/05/09/198259 &mode=thread [slashdot.org]
Re:Real-world vs. school (Score:3, Interesting)
Good point. I know a 4th year student who doesn't know C, but watch out his Counter-Strike skills are amazing.
Sigh... when will schools implement the other kind of cheating detector [evenbalance.com]?
Erm. (Score:5, Interesting)
A better approach (Score:5, Informative)
Ok, check for exact match: diff source1.c source2.c
great, I just wrote a program to check for exact matches in source code, and it took me three seconds. Maybe I should apply for a patent for my ingenious approach (maybe I'd get it!!)
At my organisation, (in India) we've been developing something like this for quite some time for our internal tests.
While most of the work isn't (and probably won't be) publicly released, we can look at a systematic approach to building a better detector.
indent -i8 -kr
sed -e 's,\([^ ^I]\)[ ^I]\+,\1
sed -e 'g/^[ ^I]\+$/d'
i=i;
You may also want to first strip all #include <> statements (not #include ""), and run the code through the C preprocessor first to take care of #define, and conditional compilation
There's more obviously that I'm not sharing with you. These are the basics that anyone could figure out in a few minutes - not years.
Re:A better approach (Score:5, Insightful)
If there's 6 extra spaces at the end of a few lines and there are exactly the same extra spaces on the same lines (variable names aside), then there's an extremely good chance it's the same code, or a cut and paste of that section at the very least.
In addition, you'd want to strip comments in your above example.
Re:Erm. (Score:3, Funny)
Flame-bait in comment aside: (Score:5, Insightful)
There's a difference, a huge difference, between collaborating and cheating.
In the real world, you _would_ get fired for taking credit for someone else's work, trying to pass it off on your own. Heck, you'd probably also violate a bunch of licenses, too
Re:Flame-bait in comment aside: (Score:5, Funny)
Actually, from what I've seen, in the real world you get promoted for taking credit for someone else's work, especially when it's one of your underlings who slaved away while you were out on the golf course.
Re:Flame-bait in comment aside: (Score:5, Funny)
Re:Flame-bait in comment aside: (Score:5, Funny)
Then you are known as a JavaScript coder
Also in the real world... (Score:3, Funny)
Repost Detector (Score:5, Funny)
Yeah, but. (Score:5, Funny)
You know they're dying to use this revolutionary compression filter technology in other places!
C-X C-S
Not really news.... (Score:2, Insightful)
Not really a big deal... Our school uses some University's program and database which not only detects fragment duplication, but also permutations of the code (such as changing variables, white space, etc.). Not sure which University though....
Re:Not really news.... (Score:4, Insightful)
Stifiling Reusability? (Score:2)
I'm just hoping that this is balanced with a few lessons on reusing and sharing code, for practical purposes.
How exact? (Score:2, Interesting)
It better check for exact duplicates only, down to the variable names. Many undergraduate CS assignments are programs so basic that there are really only a few ways to implement them. It would suck to be a student who from scratch used the same algorithm as another student, and have them both flagged as cheaters.
Re:How exact? (Score:5, Informative)
Besides, even if the system turns up a high match between two programs falsely, it is ultimately a human who gets to review the case and make the call, after (presumably) discussing the matter with the student before actually doing anything that would leave a mark on the record.
And as an answer to the knee-jerk reaction of "that's not how it works in the real world!" I tend to agree, but not completely. As an instructor of mine once said you have to learn to dribble before you can play with other people in a team in Basketball, and as such one needs to develop his or her own personal programming skills independently before he or she may work effectively in teams.
Of course, some could argue that learning in teams would be more effective and perhaps more useful, but the point is there needs to be a mix of team and independent projects. Without independent projects at all, it is difficult to be sure that everyone is competent to pull their own weight, and part of the role of Universities in the world of business is to certify that a graduate possesses a good skillset, and without both team and individual assignments, this is impossible.
Of course, as is the case with everything, this doesn't stop cheating. If one collaborates with someone completely unrelated to the class, it can't catch that, but then again, there aren't that many people inclined to work their butt off at no benefit to them just to help some other person get a good grade.... Of course, I have seen the case where a guy goes way out of his way to help a pretty girl, but that is another story entirely...
Re:How exact? (Score:4, Interesting)
He gave us a long complicated piece of c code to do this, but instead I just used a stack (we didn't "learn" about those in class untill a few weeks later). Well, it just so happened 1 other student felt like writing the 11 line stack implementation, rather than the 100+ line one the teacher recommended. The teacher then said we cheated.
Fortunatly we were both able to explain how our code worked
OT: reversing a list (Score:3, Interesting)
int list[] = {0,1,2,3,4,5};
int i,j,len=sizeof(list)/sizeof(int);
for (i=0; i < len/2; i++) {
j = list[i];
list[i] = list[len - i - 1];
list[len - i - 1] = j;
}
Reversing a linked list would be marginally longer, but a doubly linked list would be just as short or shorter than this. Only a real novice would take 100 lines of C to do it. BTW, how could you possibly learn assembly before learning what a stack is?
Re:How exact? (Score:3, Interesting)
Computer cases were the most common (4 of the 5 cases I sat in on). One day, we had three cases, with different defendants in each one. All programs, from about 15 students were essentially identical. What were the differences? Capitalization of variable names, and indenting style. That's it. So, while they were not 'exact' copies, they were close enough in my mind to merit guilt.
They were fairly trivial programs. I think a total of maybe 150 lines of code or so. Can't remember if it was some form of basic, or C (I really think it was the former). There were a few ways to do the problem (I think it sorted words or something). But the striking thing is that the variables were typical CS100 nonsense names (variablefoo, variablebar, but NOT simply 'i' for iterator or 'x') of four-five characters in length, differing only in that some students had all uppercase, and others all lowercase.
Now, I suppose that if the instructor had said 'use these variable names' there is a defense. But that was never mentioned.
I think the ultimate answer was that almost everyone admitted that they did some amount of copying, and all got zeroes on the assignment. I can't remember if any failed the class (and no, nobody was tossed from school).
But this is the interesting thing: Each of the three cases was about the same instructor, with the same program. But they were brought as three cases. We were presented the hard copy evidence for all three cases at the beginning of the morning. During a break after the first case, I flipped through the other evidence packs. I saw that the copying was very, VERY similar in all three cases. In fact, there were more similarities between program A in case 1 and program B in case 2 than between Program A in case 1 and Program B in case 2. To my mind, it was clear that the cheating was much broader than indicated. However, I was ignored. Our power was only as petit jury, judge, and executioner. We had no room to act as grand jury. (In addition, this was my first real world experience with a judicial system unable to understand technical issues. I was a chem major. Roommate was a CS major. I was the only hard-science guy on the board. The others were various history/business majors.)
Anyway, the point is: exact copies are probably always cheating. But near copies are also sometimes cheating.
Reuse? (Score:2, Redundant)
I remember when my school did this... (Score:5, Interesting)
Prior to that year, VT had an average of 75 cheating violations for the WHOLE university (25000+ students). For that one class, on one assignment, 150 students were found cheating by the cheating detector... out of the 500 or so students in the class.
Funny as hell
Re:I remember when my school did this... (Score:2, Informative)
From what I understand the method used involved comparing source and generated assembly code for similarities.
And while I'm on my soapbox, this is another article posting a supposed "new and newsworthy" technology to slashot thats really not so new. Check your facts, and find out if this is really a "first" why don't you?
Re:I remember when my school did this... (Score:3, Interesting)
Re:I remember when my school did this... (Score:2)
In most cases, professors know about cheating, but don't do anything about it. Administrators often discourage professors frmo punishing cheaters, because it can create hassles with parents, parents threaten to sue, etc. It takes a huge amount of energy to pursue a cheating case, and many profs don't want to bother.
Cheating Is Harder Than Actually Doing The Work (Score:5, Funny)
Re:Cheating Is Harder Than Actually Doing The Work (Score:3, Insightful)
If you don't understand pointers, then an assignment on that topic might be impossible for you to complete- but it doesn't take much understanding to change variable names and move around non-pointer-related code.
Then there's the people who cheat by getting somebody who does know the subject to do their work for them...
Re:Cheating Is Harder Than Actually Doing The Work (Score:3, Funny)
What about code off the net? (Score:2)
I use code I find on the internet all the time, first thing I do when I start a new routine as a matter of fact. I search for preexisting code and use/modify that accordingly. Of course only freely available code but there are tons of sources for that. How would this program detect that? I would trust some code I got from the net over something another person in class wrote, but then again I know enough to be able to see if the code is good or not and to modify it if I need to.
the real world is the same as school (Score:2, Insightful)
Mod me down for this, but consulting with a co-worker at a job and obtaining code from a fellow student is NOT the same thing. The purpose of going to school is to learn and therefore they want your work, not your friend's. At a job, they just want the work to get done, they don't care how you do it.
Re: (Score:2)
Uh huh. (Score:2)
That's sarcasm for those of you unfamiliar with the stuff.
This is not news. (Score:2, Informative)
Plagiarism is bad, m'kay? (Score:2)
Well, actually, if you take work from another co-worker and pass it off as your own, you'll be fired and prosecuted.
Don't Plagiarise - it's the law. (And judging from the snide comment, probably the reason that CmdrTaco never finished college.)
Re:Plagiarism is bad, m'kay? (Score:4, Funny)
Ok, maybe I've watched Tron a few too many times...
the real world (Score:5, Insightful)
In the real world, you are fired if you steal code from someone else without their permission, pretend it's your own, and incorporate it into the app you're writing for your company. In the real world, people give credit where credit is due.
A lot of the stories I hear about students plagiarizing each other's code is done without the other student's permission. Many systems have files readable by other students by default, and students don't bother to read-protect their files. Students will take printouts out of the trash. And of course, it's always convenient for students to claim they didn't know the other person copied their work.
It's better for students if professors have an accurate way of detecting cheating. The worst thing is if the method is inaccurate, and innocent students get accused. This method sounds accurate.
Re:the real world (Score:3, Funny)
So it's OK to plagiarize on an exam, as long as you get permission and attribute the original author!
Nothing new, (Score:2)
The software that U of T uses was developed somewhere else, I thought it was MIT, but I could be wrong.
They didn't actually tell us that they were using this stuff, I found out after I graduated from reading it in the newspaper. So it's probably in widespread use, it's just not something CS departments brag about (I guess catching cheaters is fun).
Re:Nothing new, (Score:2)
The software that U of T used was apparently quite intelligent, and could tell if two algorithms/problem solutions were too similar, not just the text of the stuff that was handed in.
Ignorance on the part of the poster... (Score:5, Insightful)
So how exactly does consulting with a fellow student (or co-worker) result in both parties having identical code? I have to say that this is the most ignorant comment I've seen attached to a slashdot story ever.
At my University they have the same code policy but they encourage you to work with others! Under no circumstances are you to copy their code line by line but you can certainly ask for their help or use a module or two. The only condition to all of this is that you credit them on the cover sheet of your assignment.
Sorry for the flame but I saw that comment and it made me quite irate.
My method... (Score:2)
Of course, with freshman assignments, they tend to be pretty damn similar even without cheating (write C code to implement bubble-sort using the pseudo-code in the book as a guide). And usually, the students that were cheating would fail the tests, so there was little need to do anything special.
Why someone would pay tens of thousands of dollars to learn nothing and end up with a job that pays well but that they'll get fired from within a few weeks...
coincidence? I think not. (Score:2)
* determines exact matches
umm, sure, diff does that
* written in 1993
I checked man on my machine and got this date: "22sep1993"
Heh.
-ted
so if another university uses the same code (Score:5, Funny)
Works on resumes??? (Score:2, Funny)
A Sad Fact (Score:2, Interesting)
I was one of the better students in my comp-sci classes and so other students looked for me for help etc. I would routinely point them to my own finished assignments as example of how to do something or provide listings in which we would discuess the assignment and how to do things.
This worked well until I got called before the teacher in regards to two students having taken my listings and typed them in ( with practically no modification whatso-ever ). I explained the truth - that I provided it for purposes of instruction not stealing and managed to escape. The other students were forced to retake the course.
After this incident I kept my eyes wider open and noticed more students "copying"...
It happens. Whether this program is really needed or not I think is more an indication of how well the teacher stresses the students on final exams and such.
consulting != copying (Score:2)
Even if two people work together on a project, as long as they write their code separately, the code will be significantly different enough that it shouldn't be recognized as cheating.
Probably what this will catch is the last minute "Quick, let me copy your program" right before it's due. And this DOES happen, and I find nothing "right" about that at all. That IS cheating, plain and simple, and should be stopped. In a class of 30 students, the instructor (or TA's) will probably be able to notice similarities. In larger classes, its easy for these things to slip by, especially if the grading process is split amongst multiple TA's.
-Restil
Cheating (Score:5, Interesting)
Cuz remember programmers: in the real world you are fired if you consult with a co-worker
As someone who TAed classes at GA Tech, I take a lot of offense at this comment. There is a difference between working as a team on project based classes (of which GA Tech has a good number off including classes where we got to hack the Linux kernel and another where we got to deliver a product to a customer) once you've shown you understand the basics of programming and wholesale copying of other people's work in entry level classes where you are supposed to be learning to program on your own.
Beginning programmers need to learn how to program, find information from MAN pages & API docs, and come up with solutions on their own before being introduced into team based environments. If not they never learn how to be self sufficient or even if they are cut out for programming at all.
It is true that in the real world no man is an island but on the flip side, how many people have worked with co-workers who completely clueless about how to perform their jobs but held degrees or certifications that implied they shoould be knowledgeable about programming? These are the kind of people who hid behind the work of others in team based projects and submitted others work on individual projects.
TOO MUCH Cheating (Score:5, Insightful)
I was a TA at an prestigious, well known computer science program. The professors there always unfurled elaborate anti-cheating policies. Cheating of any kind whatsoever would be brought before the Dean, where you are going to be subject to a wide range of punishments, including possible expulsion from the University. They purported to be using a script very similar to the one being described here. Yet many of my classmates cut and pasted their way through all the entry level classes while i labored away at every assignment. How did they get away with it?
That one issue -- that people who did no original work whatsoever got scores at least as high as mine -- has been dismissed as "a fact of life" by friends and family, and I tend to not think about it too much. Why? Because I'm the one getting the education, not them, and in 5 years when college GPAs don't matter a fraction as much as intelligence, experience, and work ability, I'll get sweet (or is it l33t?) revenge.
But in the meantime, I thought, let's become a TA and be on the other side of the fence for a change. Let me do my part to bring all these cheaters to justice.
And you know what? The reason they all got away with it was not because the previous TAs slacked off, but because the professors, when push came to shove, just didn't care. They lied about using the script.
When I brought identical assignments to their attention, they didn't pounce, but gave me options such as taking off some points or letting it go.
As it turns out, we have a very forgiving Dean, and any cheaters brought to his attention will get no more than a slap on the wrist. For that, professors get to do a lot of paperwork, cast themselves as the bad cop in making the case, and get a poor repuatation with students who are used to the status-quo of a cheat friendly environment. They don't want to do any of that , so they put on the pretense of being tough on cheating and hope it all goes away.
Slashdot is mostly a young crowd, and young are naive like I was, so let me break some bubbles: maybe at GA Tech profs let ethics take precedence over apathy, but not everywhere.
And to all your cheaters out there: yes, you're off the hook for now, but wait until we're co-workers.
Can someone please mod this out of the anonymous doldrums? Thanks.
Get some transparancies (Score:2)
My high school CS teacher once found a few identical programs. He printed out the source code to some transparancies, then lined them up, one on top of the other, on the overhead projector. The only blurred spot was the comment with the students' names.
UCLA had this in 1985 (Score:2, Informative)
So you might obfuscate your copied code by moving it around, changing variable names, etc. but it would still catch you.
Info on cheating detector (Score:5, Informative)
1. The cheating detector is not new. It's been in place for years. When I took intro programming in 1994 they mentioned it, and it wasn't new then.
2. Everybody at Tech knows about it. They tell you about this script the first day of class. Nobody here should be suprised they were caught. The fact that they were caught only shows them to be some of the stupidest people at Tech.
3. It catches people every term. Usual numbers are below 5% range. The fact that it caught someone isn't news. The fact that it caught 10% of a class is news.
4. These classes are cake. There is no reason anyone should need to cheat to pass these classes. They are the most basic concepts of programming.
University of Virginia has one too (Score:2)
A few words from a GA Tech grad (aka "flame bait") (Score:2, Interesting)
If you were gonna copy someone elses code. . . (Score:2)
This isn't a case of colaboration is bad (Score:5, Insightful)
I mean, we talked about this today in class, if a guy gets a degree and makes it out of school riding the coattails of others his degree is worthless. Once he is out in the real world, he also drags down everyone else who has the same degree from the same school because employeers will think - Guys from school x don't know jack.
CS departements are not evil, but they are trying to uphold the principles of school. Don't misinterpret actions such as these as some sort of action to "keep people down".
-RonB
Not new, but not "diff" either... (Score:2, Interesting)
It caught a few guys that I know. When confronted they tried to say that they didn't cheat. So the prof does the only sensible thing that a CS prof should do when dealing with cheating intro students: Single out a common line of code in their programs and ask them what it did. Hint: How many of you knew the ternary operator in your first forays into C?
We've been using for 8+ years whats the problem? (Score:3, Informative)
The students are told it is ok to discuss the homeworks and project with each other and that it is ok to discuss the concepts. However it is NOT ok to copy each other's code.
The program does not just compare the text of each student's homework which is what some people seem to think it does. The program gets rid of variable names, function names and things like that because a person cheating can simply change those. It compares the style of the code and it is not given common code to look at. The only code checked is the code from problems that generally generate unique solutions.
In the time I spent there I know of over a hundred cheating cases caught by the program. In some of those cases if you had of given me the 2 pieces of code I never would have said the people were cheating but when asked the students confessed. I have never heard of someone being falsely accused. Most of the time when the 2 cheaters are asked separately they admitt to it.
Once again, Tech does not have any problem with people helping each other understand concepts like the way pointers or a vector works or the differences between stacks and queues. What they have a problem with is when each studen does not do his own work on an individual homework.
Eventhough some of the problems may seem not worth it, like writing your own version of strcpy, it is still necessary so that students understand how the library functions work even if they will never be writing library functions in their life.
Berkeley cheating detection (MOSS) (Score:2, Informative)
Slashdot Boggles Me Again... (Score:5, Interesting)
A University degree is supposed to signify that you demonstrated knowledge in certain areas.
Cheating is not demonstrating knowledge.
Undergraduate level programming assignments do not require even consultation with other students, IMHO. They are too simple. If you can't code an undergraduate programming project without extensive "consulting", then you can't program. Period.
I am sickened by the number of people with CS degrees only because of "teamwork" and "consulting". I would guess, from my experience, 95% of people with CS degrees can't write a sort routine. Widespread use of these kinds of programs might fix some of this. As would harsher grading. In the real world, you don't get partial credit for a program that only dumps core or doesn't meet any of the design objectives. (in my opinion, any program which doesn't properly run a set of tests, provided to the students in the project instructions, should receive an "F" grade)
No wonder the software industry is such a mess. I've seem CS *GRADUATE* students who couldn't use malloc(). Note that I did not say "who use malloc() wrong - no, these students could not even figure out how to call malloc() nor explain what it did. There's something strange happening (I call it cheating) when someone can graduate with a CS degree yet never use dynamic memory allocation knowingly...
Re:Slashdot Boggles Me Again... (Score:3, Insightful)
I'm not a CS grad [rather, Maths], but I would not consider this a problem. What is a problem is the 95% of CS grads who don't know how to find the sort routine in the standard libraries of the language they are using.
school != real world (Score:2, Interesting)
There's a much better and more accurate article on the topic at the AJC [accessatlanta.com]. Take the AP version with a grain of salt.
The fact that GA Tech uses software to detect possible cheating should not come as a surprise to anyone. Such systems have been in use at many schools across the country for many different disciplines besides CS. Nor should anyone be disturbed by the use of such systems: their purpose is to detect possible cheating, which according the AJC article was clearly verboten to the students in the class.
In the real world, a completely different set of rules may exist, but the fact remains that if your boss tells you he wants you to do something on your own, then you'd damn well better do it on your own. When a teacher instructs a student to perform a task on his own, he so instructs not to make life more difficult for the student, but to ensure that the student is capable of independently executing the skills necessary for the completion of the assignment. When that student eventually enters the real world, he has demonstrated the ability to perform the skills to be expected of him in the real world, so when he then has the ability to collaborate with his peers, he can actually contribure to the group's performance. A student who has always relied on others to get by will offer minimal assistance to a group and will typically act as a hinderance.
So sure, in the real world you won't be fired for collaborating with your peers, but you will be if you can't get anything done without collaborating with your peers.
RIT (Score:2)
Been done. (Score:2)
The hard part is turning up the "sensitivity," so you get not just exact copies, but also people who have taken parts of a program or made some trivial modifications.
The problem is that it's hard to find info about these sytems for the very good reason that this is one instance where security by obscurity makes sense. If students know how the systems work, they can re-implement them and check to see if they'll be caught.
Greg
Take two hackers (Score:2)
So what happens when the cheating detector spits their names out?
After 20 years of professional programming, I've recently gone back to university to get my BS in Computer Science (yes, there is a wall, Virginia.) The first time this happens to me I'm calling my cousin, the lawyer. At the least I expect to have the rest of my tuition paid for. At best I want to see some lazy prof fired. I refuse to put up with this B.S.
More Info (Score:5, Interesting)
With regards to the cheater-detecter program (called 'cheatfinder'), it's significantly more complicated than diff(1). It involves checking the structure of the code (ignoring variable names , indentation, and whatnot). Admittedly, I've never seen the source for it (very few people have), but it's been around since at least 1997. The output of the program is a single number indicating the probability that two people colloborated on an assignment. The threshold is typically set fairly high (0.90+), so false-positives are less likely. 187 students, the number caught this time around, is definitely the highest I've heard of, but it's definitely not the first time we've hit a large number -- just the first time it made the cover of the local newspaper.
Interestingly, many students (including myself before becoming a TA) think (well, thought now) cheatfinder is just something the profs made up to scare students.
Re:More Info (Score:5, Funny)
Makes me think of the possibility of a new product! anti-cheatfinder!
Parse the original code and then re-organize the parse tree to be different yet functionally equivalent. Output the new code based on the modified parse tree. No need to change the variable names since cheatfinder ignores them anyways.
Then, sell the product to cheaters around the world! Hopefully they will go get jobs at microsoft!
Jeff
Not always accurate results (Score:2, Informative)
It turns out that about half of the people cheating really weren't- they just all happened to independently come up with a seperate working implementation than the Professors originally intended, and hadn't even thought of themselves.
All that ended up coming of this was that the Professors apologized on the class newsgroup- I think they still check the code using the same program.
need to add a huge database to this. (Score:2)
I also know that I would be pissed and question the credibility of the profressor that uses thison my code. Because that is exactly what the professors is doing, assuming that everyone is cheating and run them through the detector... maybe we should frisk and do drug testing on all the students, and hook them up to polygraphs during tests too just to be sure they dont have weapons, cheating aids, or are taking controlled substances or are cheating on the tests as we know they all are.
Any professor that would use this or even allow it to be used on his students has ZERO respect from me as that is the amount of respect he is showing his students.
diff don't do it (Score:5, Informative)
I was a grader for the C++ and data structures class back when i was in school. And I saw my share of cheating. One instance that stands out is when a bunch of kids had variables called "dude" and "funtime". Problem was, they had enough differences elsewhere in their code, that an automated diff wouldn't have worked. For a while, I was going to write some fancy perl that would look for certain cheating patterns that I was seeing, but then I got lazy.
One deeper way to check for cheating is to pass code through the front end of a compiler and check what comes out. if there are too many simmilarities, they will stand out even if kids change paramater names and the like.
Finaly consider this: Checking for cheaters in a class isn't just doing a diff of two files. For every student in the class, you have to check his code against everyone else's. This is a O(n^2)problem. My class had around 350 people in it
so that's 122500 checks to do. If it is anything more complex than a diff (multiple files, compiler front-end, fancy perl parcing) this can take a mad amount of computing.
This is old (Score:3, Informative)
Vanderbilt's Honor Code (Score:5, Insightful)
- Madison Sarratt (1891-1978), dean, Vanderbilt University.
Head TA Elaborates (Score:5, Informative)
No, I have no current affiliation with Georgia Tech.
Yes, the cheatfinder really, really, honest-to-God exists. We used it every quarter that I was associated with the class and caught _lots_ of people. You'd be stunned how many people thought we were just making it up to scare them into not cheating.
Yes, it actually works. It examines mostly source code, although some versions of it were twiddled to look at "in-between" assembler to help catch those who just change variable names and such. It scans for patterns in the logical constructs of code blocks, even if they've been rearranged or altered in other "cosmetic" ways. It also looks for exact matches in text (like the "commas in same places" mentioned by Kurt in the article), but this is misleading -- it does a whole lot more than that.
Yes, depending on how you run it, it can generate a boatload of false positives, but it contains several tweakable threshold levels that let you control how "suspicious" a pair-match has to be before it gets flagged, and these thresholds are made looser for simple programs where there's really only one way to do it.
No, no action is *ever* taken based on the output of the cheatfinder directly. It merely alerts the TA who's responsible for cheatfinder that quarter and he/she then manually reads the source code to see if it looks like a case of cheating. If so, it gets sent on to the professor for a final verification (and possible discussion with the student if it is a borderline case), before being forwarded to Kurt for examination and possible disciplinary action.
Finally, yes, it's an old and very "evolved" codebase. You wouldn't want to be the one to maintain it, but on the other hand, it has been tweaked to the point where you'd be really surprised at the sort of clever cheating it can detect. (i.e. it works a lot better than diffing the source code
Anyway, figured I should throw in my $0.02 on this one, since I used to run that class.
If anybody has any specific questions, please post to this comment and I'll reply. (Questions from current Tech students asking how to "get around" the cheatfinder will be happily ignored, of course.
A little insight from the inside (Score:5, Insightful)
1. These are not just "programmers" in the traditional Computer Science major sense. The first class is required for almost all students at Georgia Tech. It started off just for Computer Science and Computer Engineering, then expanded to all engineering majors (civil, mechanical, etc). Now, even management majors (Georgia Tech's version of Communications, Basketweaving, or whatever the weak major that many athletes did at your school) have to take the class. The language used to be a locally developed pseudocode language (affectionately known as Russcal). Right or wrong, many of these students consider the class to be an unnecessary hurdle on their way to a degree, and to a technologically illiterate management major, programming does not come easy, nor are they inclined to learn their ethical obligations as a "programmer" - they just want out of the class.
2. Contrary to many snide remarks, the algorithm is, in fact, quite sophisticated. It is not fooled by extra white space, variable name changes, or simple rearranging. As a TA, I saw even simple algorithms done a slightly different way by every single student. Chances are that a student who will resort to cheating doesn't know enough to rearrange the code beyond the recognition of the cheat-finder and still have it be correct, and a student who does know enough would probably spend as much time dressing it up as it would take them to write the thing in the first place.
3. Once two submissions are flagged as possible copies, they are first reviewed by a student TA. If the TA believes that they are in fact copied, it is escalated to the class manager (GT staff), and then to the dean if need be.
It's not a perfect system, but the cheat-finder does a good job of crunching the role of a human down to a minimum, and leaves room for people to make a subjective judgement. It's pretty good, so cut the sarcasm back a bit - it's unwarranted.
Wrote similar code & why (Score:3, Insightful)
As for why: everybody was supposed to do their own work -- this was not one of the courses where people were supposed to collaborate on their programming assignments (those courses came later.) Some students went overboard on the restrictions -- there was never anything wrongg with discussing the assignments (that's part of the learning process as well), but everybody needed to do their own work to prove that they understood the material.
Now that I'm out in the "real world," this makes sense -- I can tell the people who cheated and slacked their way through school, because they don't last long without understanding what they're doing.
Now that I'm out in the work
Consulting a coworker? (Score:4, Insightful)
You may not be fired for consulting a coworker, but if you take a coworker's worker and then claim you did it yourself, you'd certainly better cover your bases.
C//
Experience of an former TA (Score:5, Funny)
in general... they are the extreme... there is a lot of general cheating going on and I think something like this is a good idea... to catch "the smarter cheaters"
In the teaching trenches... (Score:4, Interesting)
- Copy the original code.
- Change every variable name (even if to a less sensible name - HalfCircleWidth instead of Radius).
- Rephrase most comments, but in the most transparent manner (e.g. "incerment the counter": becomes "the counter is incremented").
- Grab one or two lines of code near the top and rewrite them in the most awkward manner possible. Presumably, this is to prove to themselves that they're more clever than the teacher and that they could've actually done the assignment if they'd bothered.
Inevitably, it was the trivial stuff (indentation, comment structure) that set off my alarms. Then, I'd give them a moment of truth and sit them down to try to explain how "their" code works. If they didn't, I'd kick their tails out. If I was teaching a seminar at someone's workplace, I might or might not inform their management. Since all these penalties were spelled out in my syllabus, I never lost any sleep (in fact, putting them in my syllabus tends to ensure no one tries it).As to the the differenece between "consulting" with another and "cheating", I've found that the "explain your own code" is a pretty good yardstick. If I spend 2-3 hours preparing to teach a lecture, I have no sympathy with someone who doesn't spend enough time to do the assigned work but instead cheats.
Thoughts of another Georgia Tech alumnus (Score:3, Interesting)
I took Intro to Computing in the Spring of 1996. It was cake for me because I was a Computer Science major and I dig this stuff. But a lot of non-CS people dreaded that class above all others, especially Management, International Affairs, and Architecture majors, but also some engineering people, such as Aerospace and Industrial Engineering.
(And can you really blame them? How many civil engineers really need to know how to sort numbers in O(N log N) time? Or insert into a linked list for that matter? They write hacked-up FORTRAN if they write anything at all.)
Kurt Eiselt came to the first lecture and gave us a scare speech about Cheatfinder. Knowing that it looks for similarities between two students' works, I was worried constantly about my homework answers. A typical problem was to write an inorder binary search tree traversal routine in pseudocode. Honestly, how many different ways are there to do this? And there are 500 people in all sections of the class?
Fortunately, I was never flagged, but I have heard a few stories (which may not be true, you know how that goes) of people who were flagged, and were only vindicated after losing student jobs and failing classes.
I don't think an automated cheat detection system is applicable to small problem sets like binary search, stacks, and Mergesort. For the later classes, say Sophomore level, I have no problem with it though.
Besides, many Greek orders and clubs on campus have extensive "word" banks--archives of previous homeworks and tests, with solutions, from previous class offerings. Are they going to check against all previous students' work too?
"Real world" argument is such BS (Score:3, Insightful)
So, we've now proven that in the real world, you can't very well "cheat" off a coworker becuase they're doing something different. You could reuse code, but that doesn't count either. You can ask for their input, but you can't pass their work off as yours. Try that and see how long you last (probably about as long as those cheater students).
I remember a guy.... (Score:5, Funny)
But he was pretty paranoid about getting caught, and realised that a verbatim copy wasn't enough, you'd have to change the variable names, comments etc.
So he did some research, wrote himself a little parser that read in the source code and built a parse tree of the program. He then wrote another function that spat out all the code again but with different spacing, block ordering and some simple variable renaming (e.g. x,y,x->a,b,c)
To make sure the structure of the code didn't give him away, he wrote a few code transformations, e.g. if a then b else c became if !a then c else b. The order of non-conflicting assignments were swapped, and mathematic expressions were re-arranged (sometimes actually optimising the original code in the process!).
Still wasn't good enough, the comments needed changing and the structure of the code looked the same. So he linked in a thesaurus and NLP/AUG engine to change the words in a meaning-preserving manner. Same principle could be applied to the more complex variable and function names, so buildTree became makeStructure etc.
Finally, to put the icing on the cake he modified the program so it could output the code in a couple of different functional languages. Made the plagiarism almost impossible to spot.
Best programmer I ever met.
A good cheating policy (Score:5, Interesting)
CMU 15251 Course Document and Cheating Policy [cmu.edu]
His policy encourages collaboration and specifically forbids cheating. It itemizes various types of cheating, for example copying from another student, letting another student copy you, and looking at someone else's files online (even if they forgot to set their file permissions).
Furthermore, he requires all of the students in his class to sign a statement saying that they have read and understand the cheating policy. Not only does that discourage some students from cheating, but it also makes it much easier for him to get students into serious trouble with the school when they are caught.
In addition to the course document, here's more or less what he had to say on the first day of class: (I apologize for paraphrasing; this is how I remember it) "Nobody plans to cheat. You all must be very smart, or you wouldn't be here. You think you're going to try hard and do well in this class. But later in the semester you'll get busy with other classes and activities, and all of a sudden an assignment will be due in one day and you haven't started. Or you'll be taking a test and realize that you forgot to study an important equation. Or you'll work hard on an assignment and almost completely get it working, but get stuck on one subroutine. Even though you never planned on cheating, all of a sudden you'll find yourself in a circumstance like that and it will seem tempting."
(BTW, I shouldn't have to say this, but Prof. Rudich's cheating policy is copyrighted. If you're a teacher or T.A., don't copy his cheating policy without his permission. That would be just as dishonest as cheating!!! If you want to use it, contact him and I'm sure he'd be delighted to let you use it, as long as you give him credit.)
Stephen Ambrose, watch out! (Score:4, Interesting)
These instances only came to light because an author of a lifted passage noticed it while reading Ambrose's book. Subsequent episodes came about because other authors started looking, and now some people are checking out new likely sources; this works because Ambrose only lifted passages from books that he admired and heavily footnoted (at least, so far as we know!).
Perhaps Ambrose was really just lazy, as he was fairly open about crediting others for the ideas (he "just" failed to credit them for the words, too). There are many cases of sneakier plagiarism than that, both in academia and in journalism.
So, class, the programming problem for today is, given the text of two books, spit out the most likely candidates for lifted passages, based on length and similarity of words. You get a B if you can do this for exact, verbatim matches, an A if you can do it with individual word substitution, and an A+ if you can recognize re-ordered clauses. The end users for this tool would be 1) authors everywhere who want to protect their own writing, and 2) journalists looking for juicy plagiarism scandals.
Ever seen a compiler detect cheating? (Score:4, Funny)
A student came up and said "I've written all of the assignment, but the compiler is broken." My friend looked at the error output from the toy teaching language compiler.
"Unknown keyword 'From:' in line 1 'From: student2@cs.university.edu'"
"Unknown keyword 'Subject:' in line 2 'Subject: Assignment 2 answers'"
The student tried to insist that it was all his own work.
Real world (Score:3, Funny)
My experience with "cheating"... (Score:3, Funny)
Was in a class where the instructor asked us to write a program to perform an ascii sort of a file (kind of like 'sort' actually). I specifically asked if we could use libraries, and he said yes. Of course most of the students were using Pascal...
You can probably guess what I did. My program featured the prominant use of "qsort()" out of the C library. Even though I had learned about callbacks with the thing, he really didn't like it. Made me go back and reimplement it so that there was an actual "sort" being performed in my code. Ug.
Now I'm a Principal Engineer.
Re:I can make one of those (Score:3, Informative)
ln -s
Re:Moss (Score:2)