Do you mean to exclude all homeworky questions, or just undergrad homeworky questions? A large percentage of the questions that appear to be locally valorized as "non-soft" questions appear to be typical of those seen in grad school problem seminars. That is healthy exercise, indeed, but if it's the main intention of the site managers to stick to that, then it might help all concerned to articulate the distinction a little more clearly.

I like Anton's policy:

My policy has been that it's okay to point somebody in the right direction in a comment (not an answer) after it's been made clear that the question belongs on some other forum and not on MO.

I also don't think this is homework. It looks like the sort of thing a high school student might be confused about because his or her teacher never explained it clearly; any teacher who assigned a student to remember how he or she chose to define an edge case should not be teaching math.

I agree with Scott that answers to homework-ish questions should be deleted, as they will encourage future askers to try and get away with an answer before a moderator intervenes.
Also, if votes on these answers give reputation, we run the risk of being hijacked by a (potentially large enough) sub-community of people asking and answering these questions. It has happened elsewhere.

Scott,

It is usually better to do something pre-emptive — and I don't mean nuclear — than it is to bash people after the fact.

If you're not really open to all the hassles that come with running an open site, then perhaps you should consider different management models and software options.

Just for one example, if you want to exclude the sorts of users who ask "unwanted questions", then maybe you should consider putting user filters up front, rather than allowing open registration.

As a general rule, clarifying your values and articulating them up front will lead to less headaches on all sides in the long run.

I think I disagree that deleting answers to HW questions (or making it some sort of semi-official policy to downvote them) is a good idea at present, for two reasons.

1. Occasionally a "homework question" borders on a question at a higher level of mathematical sophistication, which someone else could then ask (see e.g. <a href="http://mathoverflow.net/questions/5323/infinitely-many-primes-of-the-form-2nc-as-n-varies">this question</a>) in which case it's a good idea to keep the question and answers visible for "historical reasons."

2. More selfishly, there's the simple fact that not all such questions are created equal, and it's occasionally just <i>fun</i> to take a break from answering just the hard questions and answer a trivial-but-reasonable clueless undergrad question. If I were convinced that that would lead to MO turning into "homework help central," I'd understand de-incentivizing this behavior, but it hasn't so far, so cracking down on it seems kind of needlessly harsh.

I'll post a longer rant about this later, but I would oppose deleting homework questions as long as people differ so broadly about what they think is homework. I've seen a lot of questions attacked as homework which don't ring my radar at all.

I recommend killing undergraduate homework questions without a trace. There are already great resources for these kinds of questions (I'm mainly thinking of Ask a Topologist and friends). We need a place like mathoverflow for more advanced mathematics.

We haven't really had too many homework questions in the past few weeks. However, I downvote any answers to homework problems if the person who had done so "Should have known better."