text:
Is it unethical to supply a marked solution to a student who has shown intent to cheat, with the intent of identifying them for punishment?
One of the adjuncts that I work with found that one of their students had posted their assignment on a freelancer website asking for the solution.  We joked that he should place a bid and fail them afterwards and had a lengthy discussion about sting operations and entrapment.  In the end we came to the conclusion we were not the police and to let the chair know, but ultimately take no action.
I was wondering about the ethics of anonymously giving this student a marked solution with the goal of identifying the student and removing them from the class.  In particular, I'm imagining we could write a correct solution with some additional embedded information that will be recognizable when the student turns in their answer (for example, extraneous steps that don't break the solution but don't add any value).
Some additional clarifications:

Assume that the student clearly only wants the solutions for a grade and is not asking for assistance in understanding the material
This would be done as a private transfer of documents (like email), not a public posting (like a Stack Overflow answer), to avoid issues of other students stumbling upon the personalized solution.
We would provide the correct solution, but with some additional embedded data that identifies the source; for example, metadata, comments, and, in the case of code, extraneous steps that don't break the solution, but don't add any value.

corresponding question for the legal side: https://law.stackexchange.com/q/36748

Related, and you might be interested: https://academia.stackexchange.com/questions/65485/moral-dilemma-in-unwittingly-being-paid-to-complete-a-students-work

Answers in comments, obsolete remarks and other digressed discussions have been moved to chat. Please read this FAQ before posting another comment.

[We] had a lengthy discussion about sting operations and entrapment

The distinction between the two is important here. A sting catches someone doing something they were already going to do. Entrapment is where you trick them into doing it in the first place. If you posted an advertisement offering to solve the assignment for them, and some students took you up on that, that would be entrapment, and would definitely be unethical: they might not have cheated if you hadn't posted the advertisement.
But in this case, they have already chosen to cheat. The only thing you can change is whether the assignment that they cheated on is easily recognizable as such. In some cases, it's hard to distinguish between a sting and entrapment. That isn't the case here; there's a (presumably) timestamped job posting the proves they were planning to do this before you got involved.
You should still definitely run this by the department chair or someone first if you decide to do it, though. It looks similar to entrapment even though it isn't, and it's better to justify your actions before you do them, instead of letting it be an unpleasant surprise when the student complains later.
The fact that you'd be getting paid to do the assignment is an issue, as well. Returning the fee to the cheater after catching them probably addresses this issue. (And maybe turn it over to the department in the meantime, to avoid the appearance of potential impropriety.)
Edit: A comment requested an unambiguous conclusion, so:
My view is that it is ethical, but it's very close to the border, and either encouraging cheating that would not have otherwise happened or profiting from the actions you take would push it over to the unethical side. And because it's so close, it's important to have some amount of transparency (e.g. by telling the department chair in advance) so as to avoid both the potential for and appearance of impropriety.

On top of that - the establishment might not want to know who the cheater is; as they might suspect that it's someone who made a substantial donation to the body and intentionally want to close their eyes to it.  (sad but true)  As such, ensuring that you've got the go ahead will prevent any anger getting directed at you when their donation is retracted.

"If you posted an advertisement offering to solve the assignment for them, and some students took you up on that, that would be entrapment, and would definitely be unethical: they might not have cheated if you hadn't posted the advertisement."

Maybe colloquially, but I believe legally the definition is much more strict. I don't buy that it's "unethical" either - if they're so willing to cheat all it takes is an advertisement of cheating services, there isn't much moral difference between putting out an advert and responding to one put out by them. See http://lawcomic.net/guide/?p=633

Entrapment isn't when someone "might not have done" something without your involvement, it's when someone didn't have the inclination without your pressuring them. Answering an ad is just going undercover. Putting out an ad is a sting operation. Entrapment would be something like getting a student drunk and then offering to sell a solution.

“In this case, they have already chosen to cheat.” No they haven’t, or at least if they’ve “chosen” they haven’t actually followed up on that choice, and might still change their mind. Conspiring to do something wrong (and even doing things that take you part of the way there, like posting an ad online) isn’t the same as actually doing the wrong thing. For example if I post an ad online trying to hire a hit man to kill someone, of course I’d be guilty of a conspiracy crime, which is bad, but only if someone actually ends up being killed will I be charged with a much worse murder offense.

@DanRomik Attempting to commit a crime is also a crime in many cases (attempted murder being the most well known example.)  They are attempting to cheat. Whether they fail to do so may have practical consequences, but ethically speaking, the choice has already been made.  (I like the distinction you made in your answer about punishing them for soliciting solutions rather than for submitting them. I personally believe that you'd be justified in punishing them for both, but doing it your way does avoid some moral ambiguity.)

@Acccumulation You may be right about posting an advertisement not being entrapment.  I lack the expertise to say, and can't think of a better example at the moment.  But the important thing here is that answering an existing ad definitely isn't.

@ray fine - as I said I’m in agreement that the student has already offended. I don’t have a strong opinion about whether “conspiracy” or “attempt” is the more accurate term for their offense. The point is that even an attempt is still not the same as the “real thing” - that’s why attempted murder and murder are two separate crimes. So IMO, there is an ethical distinction about whether the goal of the sting operation is to catch the student and punish them for the attempt/conspiracy (carried out before the sting), or for the actual cheating (potentially done as a result of the sting).

@DanRomik With your criteria, we couldn't do anything about a student who's obviously looking at somebody else's exam. We'd have to wait until they actually find then write the answer they're looking for from their neighbor? So they'd be able to correctly argue "I wasn't cheating, I needed question 4, but my neighbor only had question 2 open"

@user71659: having been in a situation exactly like that ("But I couldn't read anything" - with the "source" turning around "Are you saying my handwriting is not legible!?") as a fresh TA, I then was taught that my word that the student did cheat is not sufficient to take action against the student. Warning the student off ("Keep your eyes on your own sheets") In hindsight, I could have relocated the student to a seat where they could not possibly read another student's sheets.

@user71659 I did not mean for my “criteria” to be interpreted in such an absurd way. A student who’s looking at another student’s exam for an extended period of time is obviously cheating - there is no need to wait to find a copied answer. And a student who’s advertising to hire a freelancer to do their homework is already committing some kind of academic misconduct (if you think “cheating” is the right name for it, I guess that’s reasonable, although a tad imprecise IMO). But a student who is actually submitting someone else’s HW is committing CHEATING, bigtime - definitely a worse offense.

It is unethical if you plan to punish them for the offense you are “stinging” them to commit (submitting under their own name an assignment done by someone else). But I think it’s ethical, though potentially still problematic, if you plan to only punish them for the offense they have already committed (soliciting solutions for a homework assignment on a freelancer website), and are only engaging in the “sting” to solve the practical problem of identifying the student who has committed that offense.
The point is that there are two dishonest, punishable acts beings discussed here, one that was already committed and the other that is at this point only (presumably) contemplated.  The student has already done something that violates most universities’ code of conduct by posting online the solicitation for someone else to do their homework assignment. It would be completely reasonable for you to punish them if you knew who they were. So I don’t see an ethical issue with a sting operation carried out exclusively for the purpose of finding the identity of the offending student, which effectively can be regarded as doing detective work to catch a cheater. You should also plan (and document the plan in writing and/or by telling about it to a trusted party) to give back to the student any money they pay you for the freelance work, to avoid any accusations of acting out of an ulterior motive or having a conflict of interests.
As for punishing the student for the (more egregious) future offense, which at this point is still hypothetical, you should keep in mind that without your “sting” the student might well end up failing to find a freelancer to help them cheat, or simply have a change of heart at the last minute. I think it would be pretty obviously unethical to actively assist them in cheating, which actually increases the chance that they will engage in this behavior, and then punish them for that cheating. The student would be very likely to argue that they would not have gone through with the cheating if it weren’t for your “help”, and, while this may or may not be true, since you can’t say with confidence whether it’s true or not I think it’s actually a pretty compelling argument.
Finally, I mentioned that even the ethical approach is potentially problematic. What I mean is, first of all, the argument that it is ethical is a bit tricky and I’m not 100% sure everyone will agree with it. Moreover, the sting might violate some policy or be disapproved of by the administration for reasons of public relations or other things not directly related to ethics. And second of all, from an educational point of view your role as an educator is not to set traps but to educate, while still maintaining a minimum level of integrity. Since the student has not yet actually copied the homework, if there is any way you can prevent the copying from happening without a sting, I think that would be vastly preferable. (For example, you could email the class and make it clear you are aware of the illicit use of the freelancer website, and warn about severe consequences for anyone caught using it, and maybe even announce a change in the assignment due to this violation, or something along those lines that could deter the cheater.)
Edit:

People are saying OP’s proposed sting does not qualify as “entrapment” as it is usually defined. Fine, I edited that word out, but stand behind the rest of what I wrote.

People are saying the student has already cheated (or “already chosen to cheat”) and some don’t seem to buy into my distinction between the offense already committed and the one that lies in the future. To drive home this distinction, consider this hypothetical scenario: OP doesn’t do the sting but lets affairs run their course. The student who advertised the freelancer job doesn’t end up hiring a freelancer (let’s say OP can see this on the website). A week later he walks into OP’s office and confessed that it he tried to hire a freelancer and asks for forgiveness. He swears he ended up actually doing the assignment, and even has evidence to prove this - dated emails exchanged with his older brother asking him some technical questions, log files on Dropbox with earlier drafts, etc.
My question is: should we punish the student in this situation with the same severity as in the scenario where he did submit the copied assignment, and later still confessed without any prompting? It seems to me that those who think he “already chose to cheat”, effectively branding himself forever as a cheater, should think that the exact same punishment is called for (except maybe that he should also get 0 on the assignment since he never did it, but otherwise the same). And if you don’t think the same punishment is appropriate, why doesn’t that then have implications about the ethics in OP’s question?

Sorry, but if taking their money in a scheme is wrong, then planning to give it back isn't going to save you.

Well, it’s better if the plan to return the money is documented, to avoid people getting the wrong idea. Maybe that’s what you meant.

There seems to be a lot of people in this thread working off an erroneous definition of entrapment. An illustrated guide is here: http://thecriminallawyer.tumblr.com/post/19810672629/12-i-was-entrapped , for it to be entrapment one of the elements that has to be present is overcoming resistance. ...
["Will you buy me drugs", "yes!" -> not entrapment. ] ...
["Will you buy me drugs", "No.", "but pleeeeease, you gotta or bad things will happen!", "..... OK" -> entrapment. ]
It's only entrapment if OP first convinced the student to buy the answers online.

Maybe you should talk to university lawyers first. If such a scheme results in a lawsuit, the university will certainly be named as a defendant.

It seems a bit weird to me to draw a distinction between the two acts, when the first consists solely of soliciting the second.  The whole point of punishment is deterrence. I don't see how them not being able  to complete the act without help affects the deterrence value of punishment. "or simply have a change of heart at the last minute" I don't see how that's relevant. How does giving them a solution keep them from changing their mind at  the last minute.

@Acccumulation the distinction is perfectly logical. If you conspire to commit a crime, say by posting an ad trying to hire a hitman to kill someone, you would be guilty of (IANAL) something like conspiracy to commit murder. Only if a murder is committed will you be guilty of actually being an accessory to murder, which is a separate (and much worse) offense. The law wants people to change their mind at the last minute before doing bad things. (So should OP.) So it makes sense to have two separate concepts of wrongdoing, one for planning to do something bad and one for actually doing it.

@Acccumulation as for your second question, it’s perfectly possible that giving them a solution will keep them from changing their mind. E.g., maybe the solution you give them would be really good and when they see it they are tempted to use it. By comparison, if you hadn’t come along they would have hired a different freelancer who would do a shitty job, leading them to realize that the whole plan was misguided and they are better off doing the assignment themselves. All sorts of things can happen. If you had a role to play, however small, you’re in very problematic territory ethically.

I think this is the heart of the matter up to the point OP says paraphrased: 'assume they are going to cheat with the answer'.

@Murphy good point. I edited my answer to remove the reference to the word entrapment.

@Murphy What you describe seems to be the general legal definition of entrapment in American law. Other jurisdictions have different definitions (which may include the type of situation described in the question). Even if this is in the US, the legal definition may not matter, because OP is not a police and criminal charges are unlikely to be brought.

@DanRomik With regards to the second point in your edit: A slightly more analogous situation would be if the ad was posted, nobody answered it, the student did the work on their own,  didn't remove the ad, and later someone discovered the ad. If the student confesses when they don't need to, that's an indicator that they've reevaluated the ethics of cheating and may be less likely to do it again. I suspect people would be more willing to show lenience in this case, compared to a situation where the student is caught attempting cheat (even if they fail to do so).

@Ray thanks, you have a point but in any case it was not meant to be a perfect analogy. Just something to draw attention to the distinction I was trying to make. Thanks for a thought-provoking discussion, and congrats on your highly voted answer. :-)

What about a constructive approach? Since you are already familiar with the website the student is using, why not show him the way to the solution instead of handing it to him in full?
I do not know about the specifics of your situation, but in my opinion you should try to positively influence the student rather than playing a prank.
(I'd still find it pretty funny, though.)
Sending him a modified solution can create new problems: what are you going to do if half of the class has a marked solution?
In my opinion, this approach would be ethically questionable at best, because you are actively helping the student to fail.

Not sure I agree; while "positively influencing the student" sounds nice, this is a student who is trying to buy answers, which is unfair to everyone else in the class. In any case, the question asks about legal/ethical implications of giving flagged solutions to identify cheaters, not for brainstorming possible alternative approaches.

+1 University is neither a competition, nor are academic teachers judges who have to hand out punishment at any attempted wrongdoing. Catch and caution him before he has actually cheated, and then teach him how to do it correctly, which is what you're payed for anyway.

"what are you going to do if half of the class has a marked solution?" Then half the class fails.

@Acccumulation More to the point, the teacher KNOWS THE EXTENT OF CHEATING in their class. That's an excellent reason to do it!

+1: I think discussing in private how one could catch the student and what one then do to them may be a good way for frustrated academic staff to blow off steam. But if you want the students to be open and honest towards you, you should also be open and honest. This seems to me calls rather for an educational part about freelancing websites in the next lecture/seminar and to a private professional talk to the student.

No, it is not unethical. It's the student's fault for using your marked solution when he or she shouldn't have. If the student is honest, nothing will happen; only dishonest students will have problems.
Here's something comparable: in 2013, journalist John Bohannon submitted intentionally fake papers to several open access journals. He did this as a test to see which are predatory (i.e. they don't perform peer review and just publish anything for money). You can read more about this at its Wikipedia article, as well as the results of the sting as published in Science. Note that although this operation generated loads of comments and criticisms, nobody faulted John Bohannon for acting unethically, including victims that failed the test. They know that if they were acting honestly, they would not have failed. Some of the "victims" who passed were even flattered:

Other publishers are glad to have dodged the bullet. "It is a relief to know that our system is working," says Paul Peters, chief strategy officer of Hindawi, an open-access publisher in Cairo. Hindawi is an enormous operation: a 1000-strong editorial staff handling more than 25,000 articles per year from 559 journals. When Hindawi began expanding into open-access publishing in 2004, Peters admits, "we looked amateurish." But since then, he says, "publication ethics" has been their mantra. Peer reviewers at one Hindawi journal, Chemotherapy Research and Practice, rejected my paper after identifying its glaring faults. An editor recommended I try another Hindawi journal, ISRN Oncology; it, too, rejected my submission.

Here is something else that's comparable: the Sokal affair, where a physicist submitted a nonsense paper to a postmodern journal and tricked it into publishing nonsense. This time, the journal's editors were aggrieved. But if you read that article, you'll see why:

... Later, after Sokal's self-exposure of his pseudoscientific hoax article in the journal Lingua Franca, the Social Text editors said in a published essay that they had requested editorial changes that Sokal refused to make, and had had concerns about the quality of the writing, stating "We requested him (a) to excise a good deal of the philosophical speculation and (b) to excise most of his footnotes". Nonetheless, despite subsequently designating the physicist as having been a "difficult, uncooperative author", and noting that such writers were "well known to journal editors", Social Text published the article in acknowledgment of the author's credentials in the May 1996 Spring/Summer "Science Wars" issue.

In essence, the editors of the journal were acting honestly in compliance with their stated purpose. If they wound up publishing nonsense anyway, it was because they didn't understand quantum physics. Since they're social scientists, nobody can fault them for that either.
Bottom line: as long as you set this up in such a way that only dishonest students will fail, you're not acting unethically.

I think your examples are quite different, actually. No money changes hands. There was no deception. There was no breach of a client relationship. I don't think the examples you give are unethical, but differ on the case in question here.

You’re assuming the premise that people fall neatly into two groups, “honest” and “dishonest”. The reality is more complex. If I leave my wallet on the sidewalk with $100 in it, someone might be tempted to pick it up, look inside and keep the money. Did that person wake up that morning wanting to commit theft? Probably not - they might have gone for years without committing a dishonest act. So you see, creating temptations for people to act dishonestly is problematic. It might be ok under some circumstances, but requires a more nuanced explanation than “only dishonest people will fail”.

@DanRomik I'd say that honesty is doing the right thing even when tempted - for the same reason, "she tempted me with her provocative dressing" isn't an excuse for rape.

@Buffy that's a good point. You might be interested: https://www.telegraph.co.uk/news/uknews/11100041/Revealed-identity-of-Fifi-the-stunning-wartime-spy.html Fifi was definitely paid to do what she did. Was it justified? My personal answer is yes, but I'll grant that some people will not approve of what happened.

@DanRomik If I find a wallet on the street and don't attempt to find the owner, that is dishonest, I have 'done wrong'. Considering if something is premeditated or is a 'crime of opportunity' is something best done in the sentencing phase of a trial - not an excuse given for bad behavior. Is it more understandable? Yes... but it should be called wrong when the wrong thing is done.

@J.ChrisCompton of course it’s wrong, I never said it wouldn’t be wrong. My point was that it may (or may not, depending on other complicated factors) be wrong for me to deliberately engineer a situation that would cause someone else to act dishonestly when they might not do so otherwise.

@DanRomik I see what you're saying now... thought you were headed someplace different - my fault. Thank you for clarifying!

I don't really understand the editors' objection in the Sokal case. It seems they're saying "He said we published his garbage because we were too dumb to know it was garbage. Of course we knew it was garbage!" OK, so you knowingly published garbage -- how is that better?

Hate to invoke yet another controversial case, but its worth noting that a self-styled "Sokal squared" incident of similar nature has led to the professor being placed into disciplinary proceedings for unauthorized experimentation (on the journal editors). So this is not nearly as uncontroversial as you might think. https://www.chronicle.com/article/Proceedings-Start-Against/245431

@aidanh010 thanks for the link, it's the first time I've heard of this case. Still, I think it proves the point: if well-meaning people acting honestly (as in the case of the duped editors) can fail the test, it can lead to controversy. In the case of the OP's question, no honest student is going to fail, so it probably won't lead to controversy.

@DavidRicherby I read their response as saying they're not sure the content is garbage, only the presentation is, and if we judge by content (as most people would try to do, especially if one has seen lots of papers by non-English-speaking authors ) then it might end up published anyway.

On a practical level, I think you should aim to prevent rather than punish as that works better in theory and in reality.
In this situation I would publicly show the sollicitation (anonymized) as well as put in a really too-low-priced bit (=no hint of profiteering) under your own name&affiliation so they know they're definitely caught. This way you only show one way you're being alert (and your other students may be posting requests on/in another forum/language you're not familiar with). [I would actually hint you check other language requests, if possible using the second not first most frequent further language amongst your students; for example the anonymized screenshot shows browser tabs of other-language forums being open (very natural/accidental looking, they're between URL and post!).]
Because I actually caught a student trying to consult during an exam notes hidden in the toilet cistern: After lots of blah (read, unpaid hours of work for a whole committee) the student got no punishment at all (I'm convinced because an overseas student in the UK is a well-paying client). Beyond showing the whole class there's nothing to lose in attempting to cheat (further increasing your guard-dog duties you never wanted), even if eventually punished the delay between crime and punishment makes it ineffective as a deterrent; at best warns them to be more clever. The assertion in other answers that the student has already broken the rules doesn't really hold: The dean ruled that even though the student demonstrably hid the notes before and re-opened the cistern during the exam, since I'd taken away the notes the student hadn't benefitted so no actual unfair benefit occurred and the exam results stand; if anything, they were disadvantaged the second exam due to the stress of knowing they're discovered.
This is the reality in academia: The student has spent 5min posting a request online, maybe wanting to go through with it maybe not (maybe testing you're aware or not?); now a whole bunch of academics with better things to do are spending many hours on this useless non-academic (policing?) task, with a very small probability of effective punishment/deterrent at the end.
Students are already wise to the fact that you just take known-good essays, run it 2--3 turns of GoogleTranslate, and edit it to be grammatical again (with the original for meaning) and all TurnItIn/fraud-checking software will at best suggest it's suspect.

I wouldn't do it.

You're putting that answer out there and it may get used or transmitted to others.  So you are spreading both the right answer (to cheaters, perhaps not limited to one student) and spreading a flaw (even if the flaw is just fluff in the middle...it is still flawed thinking).
Don't think the risk/reward is worth it.  It's not that I'm sympathetic to cheaters or endorse liberal student's rights (the opposite).  But don't stick your hand into a bee's nest.  You don't know how this little drama will progress...

An alternate approach:  Just tell the class that you found the posting.  Inform the class that you thought about stinging and have decided not to do it (for now).  And that use of such resources is cheating and if ever discovered will result in course failure and school punishment (which can include expulsion).
P.s.  I know I will get mucho grief for this, but I strongly urge you to consider using in class exams versus projects or turned in homework.  Obviously there are some design courses where this is not feasible.  But I think exams are falsely deprecated.  Students learn a lot in preparing for exams, taking them, and then seeing the corrections.  Project work tends to be loved by college teachers since it allows more complex material to be dealt with and because it mimics research they do (or did when grad students).  But it is not necessarily as pedagogically helpful in building basic toolkits.  (Consider R. Feynman spoke glowingly dedades later of the benefits of speed algebra!)  Also, it is definitely more prone to outright or borderline cheating.

One issue I see here, that I haven't seen addressed in the other answers, is that even if you were to inform the proper channels, answer the bid and deliver a "rigged" solution, the student might a) still not use it, or b) modify it before submitting. I would imagine a) as a simple case of cold feet, the developer would still get paid, but the student might have a change of heart in the last minute. b) is more interesting, as the student might use just the general idea, a part of the solution, or even feel that it is too advanced and attempt to strip it down by introducing deliberate flaws in order to avoid suspicion that it is not their own work (assuming still that there is no reason for the student to believe that there is anything wrong with the guy who did the work).
The first point is, there is a plausible scenario in which you can't identify the student, but have done their job for them and even gotten paid (I assume that the money wouldn't be kept, but it is the transaction that matters).
The second point is, that in this case, you miss the opportunity to educate. If the student isn't identified, they might try again. Will you do the new assignment again and hoping that this time it leads to student? Also, other students are not deterred from acting similarly, especially after the word gets out that someone put the homework assignment on some webpage and got it done by a freelancer. You can't come into class and tell that you found the ad and prepared a sting operation by doing someone's homework, but the offender eluded it somehow, can you?
So, for the question about ethics, while the initial motive to catch someone red handed is in my opinion ethical, the result in case of failure is unethical (or "more unethical"). If you fail, you did the homework on behalf of a student (which is worse than if someone else did it), you got money for it (whatever you do with it, the student still paid to get the work done, and it got done without consequences by none other than you, that angle matters in my mind), and you didn't deter similar behavior in the future, neither of the offending student nor of the rest of the class. Which side outweighs the other ethically can be debated, but I think it comes at a great risk, and would recommend against it.
Someone might ask: "Should I then do nothing and let them cheat???". If such a sting operation were the only resort, I would seriously consider myself outplayed and do nothing rather than risk being part of it. I would of course keep a lookout when the homework is handed in. I would also proactively tailor the homework so that it depends heavily on the coursework and hope that an outside expert would either have to invest a non-trivial amount of time to familiarize himself with the material (which might be infeasible in terms of cost, however the pay arrangement) or have his solution stand out among the other students'.
As a final thought, consider that if you don't answer their ad, no one else might.

As long as it is completely unambiguous that the student intends to cheat, I do not think it would be unethical to "entrap" them. The important principle is that, in your capacity as the "freelancer" providing the "flagged solution", you do not at any point encourage or incite the student to cheat.
When the student is caught, he/she will probably claim that he/she only wanted some guidance, not the solution, and that the "freelancer" misinterpreted his/her wishes. To ensure that you cannot be accused of inciting misconduct, it is important that the written evidence (electronic-mail correspondence is admissible as evidence in a court of law) demonstrates beyond doubt that, after having made a good faith effort to assist the student to an extent that would not constitute cheating, the student insisted, on his/her own initiative, upon having the complete solution.

What would OP gain from failing the student, other than the right to brag in future classes? For the student on the other hand, failing or being removed from the class could have way more severe negative consequences.

And you take their money. Don't neglect that part.

@JonasSchwarz, surely the question is what the entire university loses from not failing the student. If the consequences of being caught cheating are not worse than the consequences of not doing the work at all, the "rational" thing to do is to cheat when you fear not being able to submit the work.

The usual ethics-is-complex caveat aside: I can't see how this is could be completely free of unethical behaviour. At a very simple level, you are potentially harming this student. By giving them an answer they are more likely to use it, which is bad for everyone. You could argue this is not much more likely but you'd have to be pretty certain and I don't see how you could be.
On the 'would they follow through' side, while legal and moral are not the same thing, the universality of the general principle of: 'testing the water is not the same as taking the plunge' in law is there for a reason. As is the less discussed (and maybe less universal): 'if you make it easy/tempting for someone it is less of a crime'. (I expect push back on this but its quite common and I think reasonable.)
There's more nuanced things to consider too.
Like:
Is it ethical for you to be hunting down this sort of behaviour? Is a separate question to: Is the hunting itself ok?
You are close to the student and have a position of power. Questions of fairness etc are hard to remove.

Are you sure your proof will hold?
Assume they turn in this solution. Now you have to proof, they hired you as freelancer and they can claim, that they maybe collaborated with someone who had a really nice solution without knowing of the freelancer.
In the worst case, they can insist on "I do not know, why others used zyjkbk as variable name as well and I do not care if you cannot proof anything but this variable name".
So if you want to proof this misconduct, you better catch them e.g. by using his real name on the website, not by using marked solutions.

This seems to be based on a misunderstanding of what sort of proof is necessary in cases of academic dishonesty.

I think that the legality of doing this would be in question in a lot of places. I doubt that the police could do a similar thing (in the US) without first obtaining a court order, for example.
I think the ethics of it might also be questionable, but I think a discussion with an ethicist might be in order. The reason for the requirement for a court order, by the way, is to get an independent, non interested, opinion as to the propriety, as well as the legality.
You made the right decision IMO to avoid doing this and to be cautious about it.
However, if students are informed specifically or generally that such sites are monitored it might at least cut down on the practice. Of course it would be more useful if such assignments could be marked on those sites when they appear.
Ultimately, of course, while we want to "catch a thief" it is better all around if we can prevent the theft in the first place.

Based on the comments here let me add that I haven't claimed that the activity is definitely illegal anywhere, only that it might be. Moreover, my suggestions to avoid this action is to save people from potential grief that they might suffer by taking an action that "seems fair, but is foul". I try not to recommend risky behavior and generally caution people against it. Your desires may differ, of course.

What would be illegal?

@AzorAhai, I would think fraud might be charged as someone need to misrepresent their intentions and role. Possibly others. I'm not a lawyer, but I'd certainly want legal as well as ethical advice on such a scheme. I think that a university that was known for entrapping students in this way would quickly get a bad reputation, though that isn't a legal issue.

Hard to see how this is fraud or at all questionably legal. One isn't getting money for the solution. And I'm not sure why you think that police would need a court order to do something similar. There are a lot of misconceptions about entrapment but the actual circumstances where it legally constitutes entrapment are extremely narrow https://en.wikipedia.org/wiki/Entrapment#United_States .

@JoshuaZ, I didn't mean to imply that this would be legal entrapment as it isn't the police doing it and a crime isn't being charged. I used that to point out how such things are generally viewed. Fraud doesn't necessarily require "getting money". You can defraud people in other ways.

To me the idea that this might be illegal looks quite far-fetched.  "I doubt the police could do a similar thing..." The police only investigate things that are potentially illegal, and cheating on your homework is not illegal.

@PeteL.Clark. It was an analogy. Police won't investigate cheating, but they might investigate fraud. If you represent yourself to a student in a fraudulent way, you may be at risk. A student with a lawyer parent might decide to take you down. I only advise caution. It may be illegal and it may be unethical.

If someone posted a solution on MathOverflow on a new account, and then they copy-and-pasted it into their HW, in what manner has the person on the new account committed fraud?

Hmmm. Actually, money is involved. The student who is "caught" has paid for the phony answer.

@AzorAhai, I don't see how your latest comment is related to this at all. It is the providing of the phony answer (for money) with the intent to "out" the student that is the (potential) fraud.

The question clearly asks about providing a correct solution, not a phony one.

@AzorAhai, a meaningless distinction here. The "solution" is intended to be "caught". It doesn't matter whether it is correct or not. I used "phony" only in the sense that the intent of providing it is not to help the "client" but only to catch him/her.

@Buffy I'm getting the sense you're speculating about fraud. I don't know much about what defines fraud, so I asked you. When you have an actual legal explanation of what would be illegal, please share it with us.

@AzorAhai, I'm not a lawyer, and yes, I'm speculating. My answer doesn't claim that it is necessarily illegal, and likely won't be some places. However, if you  contract with me for something and pay me to provide it, but I use what I give you to cause you harm - even if you deserve it - then I worry that I have committed a transgression and may have crossed a legal boundary as well as (potentially) an ethical one. I will have misrepresented my intentions and, while you are my "client", I'm acting against your interests.

Things are not legal or illegal by analogy.  Speculating that the legality of an action "would be in question in a lot of places" without any justification or legal expertise is, in my opinion, unhelpful.

Actually, this whole comment thread makes me wonder why freelancer sites don't impose a standard contract on the providers that prevents them from acting against clients in any way.

I'm not a lawyer, but agents of the government have to follow a stricter line then private citizens as to what is legal and what is illegal. If this is a state supported school, issues of dishonesty and entrapment may cross a line that the same behavior in a private school would not.


text:
Getting the best out of a book-reading exercise
A doctorate involves plumbing the depths of a problem and often this involves a lot of knowledge breadth-wise in related areas. Though the latter is provided by coursework, education about a precise "tool" that a doctorate may need during solving his problem is unlikely to have been provided by the courses. Often the PhD may run into huge tomes of material which he has been introduced to by Wikipedia. Intuitively he/she may feel that somewhere in those volumes lies a theorem or an idea which can provide vital keys to solving his own problem. So I come to my questions:

What should a student do to get the best out of a book-reading exercise? The question in turn assumes the student has arrived by some means at the best book for serving his purpose.
There is a trade-off involved in reading books tangential to your field: you may spend a lot of time groping in the dark looking for a bounty which may never be there. How does one gauge the potential applicability of a book to his work? When does a student decide to pull the plug on such an effort?

Related Question: Skimming through a paper

First, I would like to comment on some of your sentences. Then I will answer to your 2 questions.

Often the PhD may run into huge tomes of material which he has been introduced to by Wikipedia: I am not sure that I understand this sentence well. Are you using Wikipedia for bootstrapping and then proceed from page to page in wikipedia, hoping to find something useful, or do you use another source of idea, but jump to wikipedia to understand in a faster way the entities/concepts you find in the first place ? BTW, in most cases I am not sure Wikipedia is something we should use at the research level. The quality is clearly increasing, but this is far from perfect, and some essential intuitions are missing sometimes (almost always ?).
Intuitively he/she may feel that somewhere in those volumes lies a theorem or an idea which can provide vital keys to solving his own problem. This sentence makes me think that you maybe focus too much on a specific problem.

Now, my answers :

When I read a paper or a book, I proceed the same way: First I quickly go through the whole thing (for a book, the whole thing is generally a chapter). Then I try to understand the key intuitions and results. At that point I don't try to understand how they are proven. Then I switch to other things. When I am thinking of a problem, or when I am on other concepts, sometimes a flash occurs and I have the intuition that something I have read can be useful, then I go back to the paper/book and try to totally understand the result. Here, this means more or less homework like in the old days ;)
Reading tangential materials is a necessity. I proceed as stated above, and to make sure that I will not spend all my time on this, I decided to always spend the same amount of time reading on other fields. For me this is roughly 1 day a week, which is 1/3 to 1/2 of the time I can use for research.

source: Stack Exchange

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/

sort: votes


text:
Pure vs Applied maths, and combinatorics, in American universities
I'm in my last year of an undergraduate degree in pure maths, doing my thesis on probabilistic combinatorics. In Australia (at least at my university), Hungarian-style combinatorics is classified as "pure".
I'm currently thinking about PhDs and where to apply. One thing that I've noticed is that combinatorics is often classified under "applied maths" (for example, this is the case at MIT).
One important reason I'd consider pursuing a PhD at an American university is for the coursework component -- I'd like to broadly improve my foundational understanding of mathematics, and I like the possibility of changing my area of focus after deeper exposure to different areas of mathematics. However, I have comparatively little interest in applied mathematics coursework (other than combinatorics, of course).
I have a submitted paper in combinatorics, my undergraduate thesis will be in combinatorics, and by far my strongest reference will be from a combinatorialist. Other than my supervisor, my strongest potential references would come from areas that everyone seems to agree are "pure". The higher-level classes in my transcript will also be almost entirely "pure".

For American universities which have both a pure and an applied math program, which one does one typically choose to study combinatorics? Is it flexible? With a cursory search, I wasn't able to find a university quite so explicit about it as MIT.
For universities that classify combinatorics as "applied":

Given my situation, would my application be stronger to pure or applied maths?

Can one do a PhD in pure mathematics with the (tentative) intention for the research component to actually be "applied" (combinatorics)?

Can one do a PhD in applied mathematics but actually take mostly pure coursework?

My suggestion is to find the people whose research area is combinatorics, then the schools they are at.

As in answers and comments... "combinatorics" is not an explanatory label, most of the time. Often, it is a reasonable label only in the sense that all matter seems to be made of bosons and fermions... but without explanation? To my mind, much of the best "combinatorics" is really better described by other labels... hence, you may fail to find such work under the label "combinatorics".

If you come here for "general advice", I am afraid you'll be disappointed.

You should choose based on the people there. For each school you apply to, look through both the applied and pure departments and see where the mathematicians who work in combinatorics fit in. Most large research universities will list their faculty by research interest, or have dedicated research group webpages. For example, based on this page you probably do not want to apply to Princeton's pure math program.
Note that many schools do not, at least on the graduate admission level, differentiate so strictly about going into applied versus pure mathematics.
(For choosing the school, since you already have research experience, you should look up articles which you find interesting and find out where those authors currently reside.)
It really depends on the school. If a school has no combinatorialist in its pure maths department, and you apply there with an intention of studying combinatorics, your chance of admission is practically 0. Similarly in reverse if all the combinatorics is done in the pure maths department for the school you are applying to.
There is no "one size fits all" solution.
This again depends on the school. Some schools allow it, some schools don't. In many departments it is expected that you find an advisor from within the department and do your dissertation research on a subject that your advisor is interested in and/or an expert on. In other departments more leeway are given to students interested in more interdisciplinary subjects to be jointly advised by two advisors (possibly from different departments with different expertise). But remember, if you are going for a PhD you will need to find an advisor in any case. Shoehorning yourself into a situation where it maybe difficult to find a professor in your own department who is willing to advise you is, in my view, generally not recommended.
This again depends on the individual policies for the schools. Some departments have very strict requirements on what the students must learn for their comprehensive exams; some, not so much. Most schools with graduate programs have very clearly written information on their websites about what is expected in their degree plans. For example, here's Harvard's version for the Applied Maths degree, though it seems they are a little bit short on the exact details.

The only "general advice" I can give is this:

Don't apply to graduate schools blindly, especially since you have a confirmed research interest. Do your homework and find the experts with whom you would like to study, and apply to study with them. Write to them in advance to confirm that they are interested in taking on students, and possibly solicit advice about other possible individuals if they are not.

A good research school may not be strong in the field of research you want to do. Always, always check before applying.

This is a fantastic answer, thank you for taking the time. It sounds like I'm going to be doing some research and email-sending for each institution.

I think you are overgeneralizing from an example here; the placement of combinatorics in applied math at MIT is due to ancient historical department politics, and regarded as an amusing quirk by those of us educated at other schools.  While I completely agree with Willie's answer that you should carefully research schools you want to attend, at most schools combinatorics is regarded as a perfectly fine branch of pure mathematics.  If you want to do the pure math coursework, and you see yourself as wanting to do pure mathematics, then probably you should just apply for the pure math programs at places with some strong combinatorialists (Berkeley, Penn, Davis, San Diego, Michigan, Minnesota, etc.)

That's definitely reassuring. That short list is invaluable, thank you so much!
Perhaps my generalization is understandable given that apart from Berkeley and MIT (and CMU, which seems to have an applied-focused maths faculty), all the "top" american universities (up to rank about 20 on the QS rankings) have almost no combinatorialists in their maths faculties. I had assumed they were hidden away in applied, stats or CS.

@Matt That's an extremely restrictive criterion, and false anyways.  Berkeley has several excellent combinatorialists listed in the algebra research group.  Anyways, you'd be better off looking at a list like: http://grad-schools.usnews.rankingsandreviews.com/best-graduate-schools/top-science-schools/discrete-mathematics-rankings  The US News rankings are somewhat bullshit, but at least are a starting place.

@Matt Ah, sorry, I hadn't read the "aside from Berkeley" part of your comment (though Michigan and Georgia Tech are in the top 20 of the QS list for math, and they have easily findable combinatorialists).  Anyways, the point stands that top 20 in the world is not a very good criterion.  Minnesota, UIUC, UCSD and Rutgers are all excellent graduate programs (top 25 in the US according the US News list) with multiple combinatorialists in their pure math faculty, and which also have the breadth to do plenty of other things if your interests change.

Thanks for the US news list! That's very helpful. I wasn't meaning to say I'm only interested in a top 20 school, but not being American I had no other way to know what schools exist and are reputable  (i meant US unis in the top 20, not top 20 US unis, sorry). My supervisor is English and knows a lot more about universities there. It turns out I was wrong about that anyway, after seeing UCLA so high on the US news list I took a closer look and there are definitely combinatorialists there, though they're not listed under a research group for some reason.

Like Ben Websiter said, at times excellent combinatorialists will list something other than combinatorics as their research interest (algebra, number theory, harmonic analysis and functional analysis comes to mind). Why not ask your supervisor about a list of people whom you should approach?

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/3.0/


text:
Curriculum Vitae in application for PhD
I have contacted a professor (in Europe) informally and asked for a PhD position. She answered in positive manner and asked for a CV.
What should I include?
Do people in academia care about the usual 2-page restriction?

Generally I would say No, people do not put restrictions on CVs unless specifically asking for it.
In a case such as the one you decribe you should send a complete CV that lists everything that can be meriting for the position you will apply for. The following would be of interest:

A brief description of your drive and interest to pursue a PhD
Course work includig grades
Scientific/equivalent experience is a given of course.
Any publications and scientific/equivalent reports you have written. If you have some significant report/thesis that you have written during your education, you can list that as well. I would say that any report longer than, say, 10 pages of text might be useful to list. In such cases you should perhaps add inwhat context (Course) the text was written. In the end what a person looking for a PhD position will be looking for is someone who can successfully complete work and write it up in written form.
Scientific/equivalent presentations in a public context, open department seminar, scientific meeting etc.
Any academic work experience such as working inlabs etc.
General work experience. This can be listed to highlght work experience of any kind. This shows how active you are.
Anything else that you think will be meriting.

If you have written a paper (thesis) of some sort, provide a copy. Only one, the most important though. If you do not have one that is fine, no one would expect you to have written much.
Despite the length of the list try to make it brief and clear so that it can be assessed with ease. ry to find a good layout that make sthe structure easy to see.

The only thing I can think that's missing from Peter's list is references. If you have one or two well-placed people who are willing to give a reference for you, listing them here and providing (email) contact information would be a good idea.

@Bill Good point, I missed that. +1

Items (1) and (2) on your list are not parts of an academic CV. They accompany the CV as part of an application as a (1) statement of purpose or cover letter and (2) a transcript (the latter if needed), but are not normally listed in a CV. Degrees, overall averages, and honors should be mentioned, but "drive and interest" and individual courses are not part of the scope of a CV.

@aeismail You are right in that for you and me this would not be included but in the case of the OP I think it would be useful to include since we are dealing with a candidate looking for a PhD position. I know I would like that information. It also seems you picture all CVs having to sport the same content, I do not fully agree on that notion. A CV will be tailored in detail to suit transient needs.

A CV is customizable, but particularly for many countries in Europe, it does not include a "statement of purpose"! One must include this, but as I said, it goes in the cover letter or a separate statement of purpose that gets submitted with the CV. A list of courses would be considered part of the "certifications" that are submitted as part of the hiring process.

A good answer but it assumes the op is in science. I would suggest a less-science-specific answer as your answer is quite generalizable (and the op does not mention being in a science-related field).

@earthling Good point.

@aeismail Good points. If I read your comment correctly does that mean that the culture in a particular country or field is so strong that any deviation from a norm is unthinkable?

It's not unthinkable, but it's definitely inadvisable. The further afield you go, the more likely you're going to have an adverse reaction on the part of someone reviewing your applications!

I would be surprised if a PhD applicant really needed a CV that was longer than 2 pages. So while not a rule, it is probably a reasonable guideline.

Someone else had mentioned this on a related question here: the words "curriculum vitae" are taken from the Latin for "course of my life". So there's not much point in a page restriction :), unlike a corporate resume, which is often required to be one page or one sheet.
As for what you should put in it, Peter's answer is very comprehensive.


text:
Are there guidelines for amount and content of text in figure captions for theses?

In writing my thesis in geosciences I have a number of figures with a fair amount of text content. Is there some limit I should adhere to -- say for example max 5 lines -- before I should just write 'refer to text'?
A related question is where citations should go, especially in the case of several needed for one figure (e.g. a plot of n sets of data from n different sources). Again, is there some point where I should say refer to text for citations?

Usually, these things are specified in the style guide for the thesis at your institution. If not, then you can probably do whatever you like.

No mention of it in our handbook, so I guess I'll make it up as I go along :)

The desire for a long caption is often an indicator of an overly complex figure.

I would imagine this may vary from field to field, but in the biological sciences the caption text in journal publications is often verbose to the point of absurdity. That being said, I would simply use common sense; If the description takes more than a paragraph, you should definitely "refer to text". Generally speaking, the caption is simply a textual guide as to how to read the plot, with (maybe) a sentence drawing the reader's attention to a particular feature of the plot. It should mostly describe the plot, and only sparingly discuss it.

The only guidance I've ever been given on figures is that a reader should be able to understand them in isolation from the text. Ideally to me the caption should capture the essence of the figure.

+1 for "only sparingly discuss it". The caption needs to help readers understand your data, not your conclusions. The following are all fine things to include in a caption: a brief description of how the data were collected and/or processed, why you chose a logarithmic scale instead of a linear one, the difference between open and closed symbols, why there is a big circle around the rat's head in picture 4, etc. Any straying into the realm of interpretation belongs in the body, not in the caption.

An expert in the field should be able to understand most of the content of the figure from the figure and caption alone.  The caption should be long enough to admit this, but no longer.  If your captions seem to need to be pages long, then you need to work on making your figure adhere better to standards in the field or to be intuitively clearer.
If you run out of time to make it comprehensible, keep the caption comfortably smaller than the figure itself; having a tiny figure with a huge block of text just looks wrong.  It takes a long time to make really clear figures, but you can at least get the superficial style right quickly enough.

+1 for the comment about time. Making well-designed figures, with high information content per square inch but simultaneously readily understandable, requires a lot of work. From my experience in neurobiology, it often takes longer to prepare the figures than the text of the manuscript.


text:
Which role should other graduate students serve in a PhD defense?
In some countries and at certain universities, graduate students are advisory members of the committee during the PhD defense. In other countries like the Netherlands, a PhD defense takes place in public and everyone might ask questions at the end. Therefore, I would like to know:

How should another graduate student serve his/her role as an advisory member of the PhD committee?
What kind of questions should one ask in a public PhD defense?
How should he/she prepare for the defense (other than obviously reading the dissertation)?

I recall hearing that the Netherlands is rather different from many North American schools in that they have both a private and a public Ph.D defense, and the public defense is more ceremonial than scientific - all of the "hard judgements" are done in the private defense. This may or may not have an effect on the answers.

The first thing I would do is to ask the committee chair what are my rights and responsibilities as an advisory member. In short, what is it expected from me. I guess I would be expected to ask questions but I will not participate on the final decision of the defence.
Participation in a PhD defence committee seems to me as a good opportunity to learn critical thinking about research. The thinking every researcher should apply on his/her own work. Therefore, as a preparation I would recommend:
(as you mentioned) Carefully read the dissertation and

if you find something which is not clear to you even after several readings, ask about it
look at some of the references you find interesting and try to ask yourself: "Is this reference appropriate here? Why?"
in case some formulas or computations are present, you can try to reach the same result as the PhD candidate
if you are interested in methodology you can ask the
candidate why he/she used that particular method

to do more, you can try to find another works on the same topic, read them and compare them with the dissertation as it is always good for discussion to have more information about the topic

In case of public PhD defence, the audience can be very broad from family members who do not know what is the research about to an expert from another department who came to rise his/her ego by asking non-answerable questions. Here, the question depends on the person who is asking. No background knowledge is expected here and one should not feel restricted by the circumstances.
My personal opinion is that one can ask really about anything as far as his/her intentions are good. If the question is irrelevant the PhD candidate or one of the committee should kindly explain why.


text:
Should referencing critical comments on papers that have been referenced be obligatory?
Say a paper submitted for publication in a journal by Prof. Bertie Wooster references a paper by Dr Augustus Fink-Nottle, but that paper was the subject of a critical peer-reviewed comment by Prof. Roderick Spode.  Should I insist as a reviewer that Prof. Spode's paper should also be referenced and the criticism at least mentioned, even if I personally do not agree with Prof. Spode's point of view?
My intuition is that the reader of a paper should reasonably expect to be made aware of any element on which Prof. Woosters work is based that has been seriously called into question, so that he is able to form an opinion on the matter.  Am I being unreasonable in this expectation?

Why are you asking? (E.g.: you are reviewing a paper as opposed to you are writing a paper)

neither in this case, but I am interested in the general principle, so I don't want to get into specifics as that might influence the answers.  As it happens I have written a handful of comments papers, and it is interesting to see when they get cited alongside the original and when they don't.

This depends on why you reference the paper. If you reference it because of the details that were later commented on, there is definitely reason to also mention the disagreement. I would consider that a basic aspect of any referencing of relevant literature. If, on the other hand the comments by Spode have later been shown to be wrong (Jeeves, 2008) or irrelevant the "historic" discussion has little relevance.
So I think your sense is correct. But, the necessity to reference both depends on the reason for referencing. The two are not eternally linked for every aspect of the original paper, only the parts where opinions differ and from which the discussion has arisen.

+1 Good point about the reason for the referencing.  The real problem is that rather than being shown to be wrong by Jeeves (definitive on most things, but notoriously hidebound and reactionary on the subject of evening wear), there is instead a rejoinder from Fink-Nottle, that is rather unsatisfactory, leaving either side able to claim the other having been shown to be wrong.  Thanks for your answers to both of todays questions!

I basically agree with Peter Jansson's answer. But I'm wondering:

It's clear the follow-up papers need to be cited if they are important for the topic at hand. In that case, I'd not only reference them but sum them in a sentence or so.
If they are not immediately relevant, I'd still mention them, like

... paper [Fink-Nottle] and the follow-up discussion [Spode, Fink-Nottle2]

or, even shorter

... paper [Fink-Nottle, Spode, Fink-Nottle2]

IMHO this is very low effort, and it is being nice to readers who want to look into the first Fink-Nottle paper (possibly because its topic is closer to what they are looking for than the major part of the present paper).

+1 For myself, if it is an important matter I would take the first option, if it was not an important matter I would use the shorter method.  If someone is interested enough to go and read Fink-Nottle1, they are probably going to want to be aware of Spode and Fink-Nottle2 as well, it might be an important issue for their research.


text:
Soliciting pre-submission manuscript comments from people who could later be peer reviewers
Before submitting a manuscript to a journal, it is fairly common at least in my field (psychology) to circulate the manuscript in a limited way to a small number of people who are experts in the area and/or who would be willing and able to provide useful comments, for the purpose of soliciting their feedback and suggestions for improving the manuscript before submitting it for formal peer review.
However it seems that this could lead to a tricky situation if the editor of the journal ends up asking some of those same people who provided feedback to serve as reviewers for the paper, since they will have already read the paper and in a sense "reviewed" it one time already.
So I have two questions about this:

From the perspective of a person who has been asked by the authors to provide comments, and then later asked by a journal editor to review that same paper for publication: what is your policy, or your perception of the common policy, for what do to here? Do you decline to review the paper because you've already seen it? Do you agree to review the paper, but perhaps provide many of the same comments verbatim as before (at least for the parts of the paper that were not changed), and perhaps let the editor know that you've read it before? Or do you see your prior reading of the paper as totally irrelevant and just approach the review fresh and as normal?
From the strategic perspective of the authors of the paper, is it better to ask for comments from people who you know are likely to be asked later to review the paper? Or is it better to avoid sending the paper to these people, and instead send it to people who are not as likely to be asked to review the paper but could still provide useful feedback?

I feel this question implies authors are planning on not disclosing of contributors (e.g. who provided significant suggestions) in their acknowledgments section. That would sustain a 'strategy' as suggested in point 2 where the authors could invite someone who's likely to be chosen as a reviewer later, so as to have the paper in shape for a positive review by a same person without anyone else realising. That'd sound like gaming the peer review to me, see my answer below.

There are two aspects to this question: what should happen and what actually happens. Soliciting comments on a manuscript is of course perfectly fine and a useful endeavour. As you state problems may arise if persons commenting on the manuscript is asked to review it. Such a person should simply decline to review the paper when requested. It is thus possible that such a person reviews the paper anyway but then the problem is between the reviewer and the editor, that is beyond your reach. What you can do to simplify for an editor is to list persons who have commented on the manuscript. It will then be up to the editor to decide what becomes a breach of objectivity.
If your topic is narrow enough that the number of possible reviewers are limited, you need to consider if you "use up" potential reviewers in the process. Again, I think being open about who has commented on the paper in your correspondence should allow the editor to find good reviewers. Just because you avoid soliciting someone's opinion does not mean the editor will ask that person for a review so assessing such effects is difficult and generalized answers of little use. Knowing the field and potential problems is the only way to assess pros and cons.

+1 for "being open about who has commented on the paper in your correspondence [with the editor]". Actually, it would be better to write their names directly in the paper, in a final Acknowledgments section.

I am a bit unclear as to why "Such a person should simply decline to review the paper when requested." Could you elaborate?

I see no problem with refereeing a paper after I've commented on it to the author. I would tell the author what (if anything) I think would improve the paper, and I would tell the editor whether I think it's appropriate for the particular journal and if so then what (if anything) would improve the paper.  There have been cases where an editor asked me to referee a paper and wrote, in his cover message, that he knew (because of acknowledgements) that I'd already read the paper, so it should be easy for me to referee.

Exactly. I interpret from this question as implying that authors who are not acknowledging contributions properly might think of using this as a 'strategy' to receive a positive review. Sounds like a peer review double dip to me.

The problem is that it may be a breach of anonomity, since the peer review will probably be very similar to the one you sent to the author.

In my humble opinion, if there are no conflicts of interest (same university or funding), the referee should inform the editor that is already in contact with the author and let him choose.
In any case, consider that many journals require authors to indicate qualified referees and the scientific community is a forum for discussion.
In conclusion, be transparent, fair and honest, but do not make choices instead of the publisher.

The job of a reviewer is mainly to advise the editor on what to do with a manuscript. From the point of view of an editor, picking someone who has already read the manuscript will shorten turnaround (which is a big thing in some fields) because they need less additional time to read the paper and are likely competent to do so. Since editors rely on this advice, editors should be able to trust referees. They may consider it more likely that people in the acknowledgment section are close to the authors and potentially biased, but this is less of an issue if we talk about renowned people in the field who value their reputation highly and that are not obviously personally connected to the author.
A potentially serious problem is that anonymity is harder to keep, since raising the same points that have been raised before might, if these points are very specific or unique, make it clear who the referee is. This is the only reason why I might decline refereeing a paper I've commented on before.

I think this is a trivial situation and should involve no conflicts given everyone is being honest, e.g. acknowledging contributions.
My answers:

Normally as a reviewer I will decline to review while stating I have already evaluated the manuscript before. While directing the editor to read the acknowledgments section, which should s/he ought to have done prior to choosing reviewers. Depending on the case I may accept but I will disclose of my name and of the fact that I had discussed the paper before with the authors, as ought to had been disclosed of in the acknowledgments section.
As an author I will invite some colleague to give opinions, acknowledge his/her contribution, and will not suggest this person as a reviewer. I assume the editor will actually read the manuscript and heed the acknowledgments section prior to choosing reviewers, and trust whoever takes it up to do their job correctly.

In some fields the acknowledgement section is not in the manuscript sent for review, but is only added in camera-ready, to preserve double-blind review.

@justhalf You're right ! I don't know how this works in Psychology, and actually not quite how other colleagues do it in my field. I include acknowledgments in my submitted manuscripts, also for the sake of transparency.

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


text:
Benefits of being a guest editor of a journal?
In recent months, I've begun receiving invitations to serve as a "guest editor" for various journals from publishers I've worked with in the past that I believe are reputable.
I recognize that there's significant workload for such an issue and very little, if any, compensation, but I'm wondering what the benefits are for tenure-track faculty to serve in such a capacity. Is it worth the investment to do so, relative to the time required?

I got one of these "guest editor" invitations a few days ago, and I took it as an indication that the journal, which I hadn't heard of before, is junk.

@AndreasBlass: The journal is from a legitimate publisher.

Disciplines are typically organized in loose groups around a fairly small number of persons. They organize conferences, are editors, are on boards of professional organizations, etc. They are always looking for the next generation, new researchers who could take over when they retire. Being a guest editor for a journal, organize a workshop, chair a session, etc. signals that you might be the next generation. Having a reputation of being the next generation won't hurt when you aply for your next job. It is also good practice for when you become a regular editor.

The advantage of being a guest editor is that you can invite people to submit papers to the issue you are editing.  If there is no fee charged to authors, then the invitees may view this as a favor.  They might provide you with a favor in return.
You can also invite authors who are likely to cite your own work.
Your institution's tenure and promotion committee may view serving as a guest editor favourably.
Edit:  You should certainly never solicit any reward or repayment from any authors you invite.

BE CAREFUL, I think favor-based invitations are not ethical. And You can also invite authors who are likely to cite your own work is absolutely wrong, check this http://retractionwatch.com/2018/02/02/three-papers-retracted-cited-frequently/.

@Haz I disagree.  How would you go about inviting people who will not view it as a favor?   Are you saying all favors are unethical, or just ones that invite someone to submit a paper?  Inviting authors in your area of expertise as the guest editor and inviting authors who are likely to cite your work are indistinguishable strategies.  Editorial decisions, however, should be impartial.  An invitation to submit and a decision to publish are totally different.

Maybe the better way to say it is building goodwill.

In the journals I’m familiar with, guest editors simply invite papers and write an editorial. The invited papers go through the regular peer review process with the normal associate editors.

-1. For an editor to send out invitations to submit papers with the intent of benefiting themselves in such a way would be unethical and an abuse of the editor’s power. You can send invitations, and it’s fine if those invitations generate “goodwill”, but that shouldn’t be your goal, and it shouldn’t influence your decisions of whom to send such invitations to. Nor should the invitations be formulated in a way that makes them appear as “favors” or contain insinuations that they are conditioned on some kind of quid pro quo.

@DanRomik I did not address what goals a guest editor should have.  That was not part of the question.  I strongly agree that nothing should be insinuated.  However I do not see how invitations could be issued without leading to these indirect benefits.  This is what the asker wanted to know.
Personally, I do not care one bit what the "intent" was, it is the actual actions that matter.  The intent of self-promotion or the intent of contributing to the discipline can both lead to high quality academic work.  They can also both lead to low quality work.


text:
Is physics taught using phrases that are too easily misinterpreted, and can this be improved?
To explain, let me pick a particular statement: "the electrostatic force is mediated by the exchange of photons".
When a physicist (or a lecturer) says this, they mean one thing: the process described in detail by QED. When a student (or an amateur) hears this, they think of two electrons, and they imagine photons flying between them. You can imagine what follows: questions like "how do they know where to fly", or "what is the frequency of these photons", or "where does the energy to create those photons come from" etc.
When I was growing up, I had no access to anyone who really understood physics. All I had were books filled to the brim with phrases like the above. It is nearly impossible not to misunderstand something when such loose statements are used, as popular literature tends to omit the extremely important "but"s.
For example, in the statement above, the "but"s omitted are "but we don't actually mean photons, in fact we don't mean any particle at all; what we mean is a mathematical tool we use to calculate how the interaction works, which is reminiscent of actual photons in so many ways that we can often treat the calculations as if they involved actual photons".
What is the most effective way to educate students about such phenomena, where our language we use to describe them risks obscuring the reality, and/or misleading the students? Is there evidence in the pedagogic literature on this?

The situation with virtual photons is made even worse because the wiggly internal lines in Feynman diagrams look a lot like the wiggly external lines.

The problem is, the language of science is mathematics, and the words used to refer to the math -- like those used in ANY profession -- are not English but jargon, with very specific meanings which are not fully congruent with how English uses the same word.  Unfortunately the alternative of inventing completely new words to distinguish these would both involve HUGE amounts of work and lose the analogies which caused us to pick this vocabulary. And nothing less will stop people who insist upon deliberately ignoring cantextual meaning from creating misunderstandings. They ain't worth the effort

That is why hire teachers: they not just read up a book, but teach kids how to interpret the sentences and warn about possible missinterpretations.

I've been thinking of this exact topic from a pedagogic standpoint for years.  I taught high school physics where I had classes that ranged from 9th grade Conceptual Physics, to APB (non-calculus) physics, to APC (calculus-based) physics, to a 12th grade second physics class for students who wanted more physics but didn't want the rigor of the AP classes.  I'm about to begin teaching a college-level Physical Science class where I'm faced with the same problem:

How do I teach the students "physics" (quotation marks in bold) without (a) saying something misleading, and (b) so they get a clear understanding that won't hinder them in future classes.

I believe the answer to that question relies most importantly on the level the students are at (teach to their level so they understand), and also with the explicit caveat that the teacher must tell the students that there are subtleties that will become apparent in future classes.  Indeed, some of those subtleties are more than that -- saying that

Energy is the capacity to do work

may be circular and meaningless (as JoeH replied), but to a first approximation and definition it works for the time being, and can be improved upon in later classes.  When I give that definition to my students, I always caveat it by saying, "Guess what?  This definition isn't perfect, and in future classes you'll learn a more refined definition that involves other concepts that aren't within the scope of this class." (I say that a lot in introductory classes!) To the students that want more information immediately, I point them in the direction of other resources, or move the conversation to office hours.
The hardest part about proceeding with this method is to make sure that you don't lead the students into an incorrect conceptual understanding that is hard to break in future classes.  Joe's example of "the potential energy of the ball" being incorrect without the idea of a system is a good one -- there are many times when simplifying too much leads to a fundamental misunderstanding, and as teachers we have to avoid that as much as possible.  Learning what does and doesn't lead to misunderstanding takes time, but being able to formulate precise assessments (whether test-based, or clicker-based, or on homework, etc.) goes a long way towards determining whether or not a student has a proper understanding that doesn't involve misconceptions.  If those misconceptions arise during the assessment, it is the teacher's duty to go back and clarify, or re-teach if necessary.
JoeH listed a number of physics concepts that take a concentrated effort to teach properly, but I think all disciplines have those problems:

Chemistry: electrons do not orbit in "shells," despite what millions of students learn every year in elementary school.
Computer Science: in some cases, bubblesort does beat quicksort.
Mathematics: the internal angles of a triangle do not always add up to 180º. Five times five does not always equal twenty-five.
English: passive voice is not always wrong.
History: a historian does not always have to be unbiased

(apologies for examples that aren't perfectly clear -- I'd be happy to amend my answer with better examples!)

This is also a problem in Chemistry. It seems students are "taught Chemistry" in their first two-semester, general inorganic Chemistry course. Then they are re-taught Chemistry in organic because everything they know is wrong. Then they get to physical Chemistry and are re-taught Chemistry once more. This repeats ad nauseam until the student graduates.

"Five times five..." No, you're linking to 0x5.  Hexadecimal is not decimal.  And 0x19 is the hex representation of 25 anyway.

A very good question.
I usually deal with this like:
"Vectors usually have magnitude and direction. Their components are usually scalars. There are more difficult cases, do you really want to deal with them now? [People sigh or say "noooo"] So, here is an example... Now we can continue.".
Of course, strict definitions give some comfort, but may also result in misunderstanding. It's good to confess that every detail is very difficult and even You, The Teacher, can not answer everything.
By default, you must know very well what you talk about. Then you can give some simple example, then a difficult one and ask them if they want to analyse it now. They usually say "nooo" and you proceed.
There are usually enthusiasts and passive people in a single classroom. It's a good practise to let enthusiasts give one or two questions above the course during the break, so that everyone gets what he's interested in. An interaction with your audience gives better feeling of what they actually need explained.


text:
How much detail to include in first email to potential PhD supervisor?
First, I must mention that I found  these questions helpful:

Prospective PhD contacts potential supervisor but receives no answer after 2-3 emails, what to do?
What to do when emails to a potential advisor are not replied?
Should résumés be attached in a mail to a professor?

Yet, I am looking for more precise answers to the questions below.
I plan to apply for a PhD in Computer Science this year in several countries, mainly Europe, Australia and Canada. I am looking for a PhD  with funding. As far as I know, I should contact potential supervisor as a first step. However, I am not sure about how much detail should be included in this first email. Specifically, with regards to the first email, I would like to hear advice on on the following:

Generally, how much detail should I provide?
Should I ask about the chance of getting funding?
Should I send documents or only if s/he asks for?
Statement of purpose/motivation, what is the right length? Is s/he ready to read two pages about every applicant sends him/her email?

Taking into account that this is the first email to the potential supervisor and he might spend only 10 seconds scanning it, What is right answers for the questions above that make the supervisor starts a discussion rather than sending negative response or even ignore the email?

It's not the first step when admissions are done at the departmental level; this is only true if the individual professors hire the PhD students directly.

Thanks @aeismail , That's totally true. In my initial quest specially in Germany, I found most of them hire based on he supervisor' opinion. Do you agree with that ?

My answer is going to extend up this earlier answer to a similar, although broader, question.
Some background: I have worked with two pretty well-known professors in Austria and Switzerland, and can provide some insight into how they tend to hire. I assume other professors have similar MOs, but not every person is the same, so your milage may vary.
Indeed, for both of them, the first step towards starting a PhD is to send them a short informal mail stating your interest in joining their group. Your challenge is to get the professor interested despite him reading maybe a 100 mails a day. You can already see why a two-page text has a 0% chance of being read, same is true for an attached CV or an elaborate research proposal - you need to convince in maybe 10 seconds. Your second challenge is to separate yourself from the dozen or so other people that are trying the same every week, mainly coming from universities in the far east.
In that light, here are answers to your questions

Generally, how much and deep details should I provide?

I would go for none, honestly. Discuss concrete research ideas at a later point, when the professor has shown interest.

Should I mention anything about fund chances?

God no.

Should I send documents or only if s/he asks for.

Yes.

Statement of purpose/motivation, what is the right length? Is s/he ready to read two pages about every applicant sends him/her email?

Forget it. None of the professors that I worked with is interested in those formal application documents at any point during the process. They will either want to skype with you or have one of their senior staff skype with you, and then you would explain the things you would write into a SOP. To be clear - I have received a PhD student, a postdoc, and a senior postdoc position without ever being asked for a SOP or letter of motivation. Those are required only if hiring is done by a committee, e.g., for faculty staff.
Here is an example of a mail that might work on the people that I know.

Dear FIRST-NAME,
I am currently looking into options for getting a PhD. I have looked into your work on IMPORTANT-THING-PROF-IS-WORKING-ON, and I would be really interested in joining you on this line of work.
I have recently graduated from XY with a degree in YZ, and I have a background in SOMETHING-RELATED-TO-THE-ABOVE. I have done internships at BIG-NAME-A and BIG-NAME-B and already published X papers on SOMETHING-RELATED-TO-THE-ABOVE during my masters.
I would be happy if we could discuss matters further via Skype.
thank you in advance,
YOUR-FIRST-NAME
YOUR-WEB-PAGE

Note the informal tone. This might be a personal preference of the people I know, but an informal mail is significantly more likely to be read by both of my professors than a very formal one. Further, note that it will be required that you have some measure of achievements that the professor can relate to - graduating from a university that the professor maybe has never heard of alone will not be enough to get him interested. Already having published and/or having done internships at well-known companies (well-known also to the professor!), especially those that are known to have competitive selection schemes (e.g., IBM), helps a lot here. Do not bother sending your GPA etc. - people in Europe tend to not be interested in grades in my experience.
Another thing that might help with the people I know is work on open source projects (e.g., being a committer or committee member to one or more Apache projects, having a well-maintained Github page with interesting tools and Gists, etc.), but this may be mostly because I work in software engineering (and people that know how software is built in real-life are very valuable to us).
Another important topic is english language - if you cannot speak / write english well, let the mail be proof-read by somebody who can (according to the way the question is written, this should not be an issue for the OP, but this may be relevant to other readers). Mails in terrible english are almost always discarded immediately.
Finally, the above sample contains a link to a web page. Have a personal academic web page. This is the place where you would put a good picture of you and all your academic achievements (papers, CVs, research interests, internships, links to open source projects you contributed to, industry projects that you worked on, whatever). Make it look professional and pretty.
Note that this mail still has a high chance of being ignored. In that case, give the professor a week or so and then write a a one-line reminder as a reply or forward of the original mail. If he does not respond after that, move on. Then he is just not that into you.

Will it seem awkward if I do this for an MS admissions as well? I am planning to do a MS in US with thesis and I am applying to this particular college for this particular professor who I wish to be my thesis adviser.

"Those are required only if hiring is done by a committee, e.g., for faculty staff." - so you mean that SOP are meant to be written for and read by faculty staff, not the professors themselves, right? Also, isn't going none for deep detail eliminate your chance to prove that you have a well-developed research interest?

To add: make sure any attachment is small.  I hate getting MBytes of attachments.  Asking for funding is a big no no, especially in Australian unis

Do not send a stock standard email.  I delete all those.  If the email says they have read my work and it is obvious they have copied and pasted some titles of my papers then they are lying.  Delete!

At most write an email about 6-8 lines long; people are busy. You should introduce yourself, explain what kind of research you want to do, ask he/she if she is taking on a student, and reference a few of their recent papers that you are interested and why. Include a small CV attached in the email.
If the professor responds, and offers to answer questions, then ask about funding. Statement of purpose length should be specified in the application process. Don't send your statement of purpose unless they specifically ask for it on their website.
It really depends on the field, but using these general guidelines almost every potential advisor responded this application season. Just because they respond doesn't mean you will get in, but it should improve your chances if you come off in a positive light.
Good luck.

Thank you, I'm applying for Computer science. My next question is, when I refer to the supervisor papers, how deep should I discuss papers? Should I provide new ideas on how to build on his work or it is enough to talk generally like I'm doing literature review without any conclusions?

How deep can you get in 6-8 lines and still provide other information? Just enough to show the professor you have done your homework on them and you can relate it to your future/current research interests with them.

I spoke to many supervisors in my applications for Computational Biology PhD's in the UK and got very enthusiastic and positive responses and lots of offers. They pretty all went something along the lines of:
Dear X,
I am a X student at X and I've been looking at your work in X and I'm very interested in doing a PhD in this area, do you have any positions available? Also do you have any time to Skype so we can talk about your work? I have done X which is why I am interested in X and my experience is detailed further in my CV (attached).
Best wishes, X
Obviously omitting/changing details if they have advertisements for positions out etc which you can then say you have seen, I recommend making your CV as strong as possible and also offering to Skype shows you are willing to spend time talking to them! I also sometimes asked them whether they would consider me or checked whether they felt I was complementary to the group/had the right skills.