On the Feasibility of Homework Questions

Question

Current policy is to close all questions that "feel like homework" to at least five (high-reputated) people. Those more militant even downvote answers given by others even if those were hints rather than complete solutions. I want to argue for stopping this crusade and allowing all kind of questions that are posed well (to be defined) and concern TCS.

First, rational reasons:

1. We cannot for sure distinguish homework from other questions¹
2. Getting help/inspiration is not always forbidden, sometimes even encouraged
3. We are not responsible for other people cheating
4. Some people are willing to help with low-level question

Second, opinions:

1. By providing help for homework questions we can reach new users
2. We should let people help that want to
3. A well-posed question deserves at least some hints
4. Such questions will continue to pop up, always, thanks to Google. We may as well answer them.

The only two reasons I ever read against homework/low-level questions are cheating and scope. Cheating I consider not an issue (see above) and scope should, imho, be defined by active users. If such answer low-level questions, so be it. Those who have some pure utopia in their minds should evaluate wether or not they really speak for most people and/or the greater good. Using RSS it is easy enough to preselect questions based on their titles.

Your thoughts, please.

Ad (1): Let me link to some accepted questions one might consider as homework level:

• Proving skip-lists strongly weight-balanced in expectation (skip lists and more complex analyses were covered in a Master course I took)
• Writing universal recursive function (content in the very first Bachelor TCS course)
• Is the following problem NP-Hard? (although allegedly no homework, simple NP-hardness proofs are Bachelor level)
• Is there a non Turing-complete model of computation whose halting problem is undecidable? (could very well be asked in basic TCS courses for intuition building)

Answer 1

The danger of allowing homework problems, besides the ethical issue, is that we may be swamped by low-level, easy homework problems, and this forum may degrade into a homework-solution forum.

The danger of banning low-level non-homework problems is that people who are not theoretical computer scientists may stop asking questions here, and we may miss connections with practice. For a notable example, by far the most important recent advance in information theory came from the interaction of theory and practice, and I would like to encourage as much of this interaction here as feasible. Most non-TCS people won't be able to tell the difference between an easy and an interesting TCS problem.

Of course, we may have to answer a hundred low-level questions from practitioners for every interesting one we get, but I don't think that's bad, because (1) Answering low-level questions doesn't take much time, (2) It's being done on a purely volunteer basis, and (3) We'll end up helping lots of people this way.

I don't think there's any chance we will be swamped by low-level problems if we don't take homework, and homework problems have no possibility of leading to important theoretical advances. The problem is distinguishing homework from non-homework.

One way of distinguishing homework problems might be asking (in the FAQ's) people to give some small amount of motivation or background for their problems. That way, if something looked suspiciously like a homework problem, we could ask for more motivation. I'd be interested in seeing a little bit of background or motivation for some of these problems, anyway.

Answer 2

I think it's a little unfortunate that the question has conflated two separate issues that Peter masterfully disentangled (insert bad quantum joke here). As Peter says, homework questions BAD, non-homework low-level questions FINE.

Consider the question of NP-hardness that the question mentions. The OP specifically indicated that they were blocked on an NP-hardness question related to their actual work, and Tsuyoshi's comment was all they needed. This might be wishful thinking, but if we can encourage people to ask NP-hardness questions and help with answers, more applied researchers might start doing this on a regular basis, which is great for theoryCS.

But homework questions cause a flood of more homework questions: this has been well documented on both SO (which has a homework policy) and MO (which doesn't allow it). I am not interested in visiting a site that only helps with homework, because it doesn't help me with my work, doesn't teach me anything, and doesn't even help with the larger goal of theory outreach. Secondly, homework questions are usually posed by drive-by questioners who have no interest in sticking around and helping grow this community, so I see no reason to cater to their needs.

To say that since people will continue to ask homework questions, we should answer them is analogous to saying that since cranks will continue to post P vs NP proofs on comp.theory, we should entertain their posts. We all know what happened to comp.theory and I have no desire to let that happen here.

Just to reiterate: this is not just a moral issue, and in fact all the reasons I cited above are purely selfish. I want a site that I find useful and can derive value from, not one where my only task is answering homework questions.

Answer 3

Let think about it as a TCS problem. Most "homework question" are easy to spot, these are the one that are $\epsilon$-far from being at the research level. Then there is a grey zone of "hum, is this homework, or is this a question of someone not in the field?", for this one some questions stay, some are killed by the crowd, and I think it's fine.

Originally, the site is about research level question, and in my opinion it is OK if some basic question stay as long as their density is low. To be more clear, I won't keep reading/asking/answering if I have to spent too much time to separate the wheat from the chaff.

Concerning non TCS researchers that could be disappointed by this policy, I think this is not a real problem. a homework question by a student and a basic question by someone of an other field are clearly stated in a different manner (more documented for instance, and the latter is likely not to use the usual jargon).

Finally, you are saying that "scope should, imho, be defined by active users.", this is currently the case, unless you mean something I don't understand. You can vote for reopening question, and if enough persons are in agreement the question will be reopen, so I don't really see your point.