Although I haven't been part of Math.SE long, I see a great deal of internal conflict over the issue of cheaters, i.e. people that intend to plagiarize the answers. This is separate from the issue of poor posting ettiquete (e.g. "Prove this" vs "How can I prove this"), and separate from the issue of giving sufficient details and showing work attempted so far -- all of these can be addressed by polite comments to the submitter, and none are as serious as the cheating issue.

The primary argument against cheaters is that of moral outrage; secondary arguments include wasting the solvers' time and besmirching the site's reputation. There aren't a lot of arguments in favor of cheaters, except that we don't have a good way to detect them. Responding to suspected cheaters has a wide array of approaches:

  1. Do not answer and/or downvote the question.

  2. Leave gaps in the solution.

  3. Give an unhelpful solution using advanced techniques.

  4. Downvote any answers believed to be too complete.

  5. Close the question.

The problem with all of these approaches is that if a non-cheater is misidentified as a cheater, the submitter is not getting a proper answer, which is the whole point of this site. There is also often the implication of cheating even if the only problem was poor etiquette. Further, approaches (4) and (5) are particularly toxic, since it discourages anyone from answering anything for fear that the answer may be suppressed or downvoted for moral reasons. Some people will hide part of their answer with >! which is helpful for non-cheaters but doesn't do anything against cheaters.

Here is the alternative that I suggest. The intent is to create minimal problems for legitimate users (self-study, collaboration allowed, homework not graded, supplemental problem, etc.) but maximal problems for cheaters. Into answers for suspected cheaters, insert a copyright trap, specifically an advanced tangential technique. Should a cheater copy verbatim, the trap will immediately signify to the grader that plagiarism has occurred. However, without the copyright trap, the solution is still complete, correct, and helpful to the asker. A poster genuinely trying to understand the solution will ask about the trap, while a cheater won't.

Example Calculus Question: Find $f'(x)$, for $f(x)=3x^2+7x$.
Example Answer: Because polynomials are $C^\infty$, $f'(x)$ must exist. Using the sum rule for derivatives, $f'(x)=(3x^2)' + (7x)'$. (etc., detailed and complete answer)

Example Precalculus Question: Solve $3x-7=5$.
Example Answer: We want to eliminate the $-7$ by adding $7$ to both sides, to get $3x=5+7$. But also $5+7=12$. Because equality is transitive, we can combine these to get $3x=12$. We now divide both sides by $3$ to get x=12/4. But also 12/4=3. Again since equality is transitive, we combine these to get x=3. $x=12/3$. But also $12/3=4$. Again since equality is transitive, we combine these to get $x=4$.

An attentive cheater might remove such a trap sometimes, but it only takes one oversight to get caught. The only way to consistently remove traps is to genuinely understand the solution from start to finish, in which case a cheater has been converted to a learner.


closed as not constructive by Andrés E. Caicedo, Lord_Farin, Davide Giraudo, Tom Oldfield, TMM Apr 30 '13 at 20:34

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  • $\begingroup$ I'm sorry, but I don't understand what you are proposing to do. What exactly are the traps in your examples? $\endgroup$ – MJD Apr 25 '13 at 20:03
  • $\begingroup$ A calculus student would not normally know what $C^\infty$ is, and its appearance in a student's solution is highly suspect. Similarly, a precalculus student would not normally know about transitivity and other properties of relations. $\endgroup$ – vadim123 Apr 25 '13 at 20:07
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    $\begingroup$ Is the fact that you divided by $4$ instead of $3$ in your precalculus example an intentional trap or unintentional? $\endgroup$ – Ben West Apr 25 '13 at 20:12
  • $\begingroup$ @Ben, that was my mistake. This was not a trap, as it is certainly something a non-cheater might do. A trap must be correct, it is terrible policy to deliberately introduce errors into solutions. $\endgroup$ – vadim123 Apr 25 '13 at 20:23
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    $\begingroup$ I'd just like to point out that you are free to downvote solutions you consider too complete if that's what you want to do. They're your votes. (Personally, I upvote good hints more than complete solutions if I'm given the choice, but I don't downvote complete solutions if they're good. But these are my votes.) $\endgroup$ – Alexander Gruber Apr 26 '13 at 0:30
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    $\begingroup$ @Alexander, of course we are all free to vote as we like. However in my opinion downvoting "too complete" answers has a chilling effect on people wanting to contribute and is a bad idea. $\endgroup$ – vadim123 Apr 26 '13 at 0:32
  • $\begingroup$ @vadim123 Sure, that's why I don't do it. I'm just pointing out that it remains an option, i.e. this solution is already somewhat in effect. $\endgroup$ – Alexander Gruber Apr 26 '13 at 0:43
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    $\begingroup$ @vadim: We don't want all contributions. We have dedicated flag reasons for answers that don't attempt to answer the question, that are spam, or that are offensive. Factually incorrect answers regularly get criticized and down-voted. It's a good thing to have a "chilling effect" on the contributions we don't want. Of course, the challenge is how to chill the contributions we don't want without chilling the contributions we do. (and the disagreement over exactly what contributions we don't want) $\endgroup$ – user14972 Apr 26 '13 at 4:43

One of the fundamental premises of this suggestion is flawed: there simply is not general consensus that we desire "questions" containing nothing but a homework problem statements just as much as any other question.

While some people do (loudly) advocate that all questions are valuable, I believe there is near unanimous consent among those proposing a more aggressive policy that the sorts of questions under consideration are very much not desired, even if you ignore the topic of cheating.

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    $\begingroup$ Forgive me, but I don't understand how my suggestion has that premise. Quite the contrary, I am proposing a solution that will diminish the frequency of such questions, without needlessly punishing or alienating posters that are ignorant of etiquette. $\endgroup$ – vadim123 Apr 26 '13 at 0:31
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    $\begingroup$ @vadim: When you say the submitter is not getting a proper answer, which is the whole point of this site, I take that as depending on the assumption that the site wants questions like the ones people are proposing to ban (and wants them answered). I don't see how your proposal would diminish the frequency of such questions except, perhaps, helping catch a few cheaters (who we assume will then stop asking more questions). $\endgroup$ – user14972 Apr 26 '13 at 4:32

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