I also would think a post on an exercise from Mac Lane's book, along with a summary of a failed attempt and a question directed toward understanding the failure and/or a key perspective, would be appropriate: it is such perspectives and understandings this site intends to promote. The question under discussion seems to request something the site does not promote, in my view: a large collection of answers to questions designed to exercise one's understanding. (Even Knuth wants you to do some thinking before, during, and after reading his exercise answers.)

What would be considered a good answer to this question? You might suggest some possibilities yourself, or illustrate by saying something like "I get that for the Jacobian conjecture, it is the naturality of the statement, like the Jordan curve theorem, which I don't see here", to give people an idea where the ballpark is or isn't.

You might search MathOverflow for questions involving vector spaces and the axiom of choice. You may find something to help answer the proposed question. With choice, I think the answer is yes because the subset of Perm X "has enough torsion", but I do not know a convincing proof.

So it's a (to me) user interface change (grumble). Thanks for the enlightenment, @quid. Now I'll try looking for a positive frame for this picture. If mods so wish, they can remove the question with no complaint from me.

Unfortunately I can. E.g., a recent question on the main page (about a three prime lemma by Lucido) has a group theory tag, which one also sees when clicking through to the question itself. Clicking on either tag instance takes me to a page with one group theory question listed: a featured question with bounty ( which is not about Lucido's lemma). I was expecting a longer list.

It may or may not be homework; it does not seem on topic for MO either.

It may be on topic for math.se, but less so for this forum. I have my doubts that research efforts can be furthered by having results delivered en masse. Furthering understanding of existing subjects, yes: taming the frontier, not so much. While MathOverflow is both about taming and understanding, the post is rather like asking for solution manual recommendations for undergraduate level subjects, not like reference requests to the literature. If the poster wants textbook/solution manual recommendations, have the poster try math.se

Oh, you want younger, more lively people to be experts and collaborators? I guess if they collaborate with you, you get to be as choosy as you want. I had suggested those two as experts in certain fields in geometry, not as potential ANT collaborators. But who knows? ...

Do as you will. In my view, both H. S. M. Coxeter and Marjorie Rice are experts. In the unlikely event you need further inspiration, check out Wikipedia's list of amateur mathematicians. If you post a link to your idea on your user page, I'll check it out. (Not an ANT.)

I don't mean to suggest that Kieran is not an expert, nor that he (gender assumption) has not already tried some of the suggestions; apologies to him if it comes across poorly. For future readers, I stand by the suggestions: I don't expect to see a mathematical match.com anytime soon, nor a specific site of the kind desired in the question.

Even better (in my mind): a one-time MO.meta pointer to an MSE maintained list on MSE.meta. (See related comment on my answer.)

My (likely faulty) impression is that there are tags only moderators or trusted users can apply, and everyone else can only request. The overflow tag (you can change the name later) would be used as a moderator tool to improve the MSE site. If you don't want MSE moderators mucking about on MO meta, have them post a list and update it on MSE meta and announce its existence on MO.meta.

I think the record of the process should be made visible, with acknowledgment of refining comments. Even if the first question was poor, it often is what occurs in initial approaches to a topic; the refining comments help steer a newcomer in the right direction, especially when the newcomer has arrived late to the party.

@quid Interesting. Is it a misuse because of the suggested tag name? Or is it a misuse to classify things by level of difficulty?

In my viewer, the question content appears as one paragraph. I think the content deserves three. Also, I think more success will be had if you add something like "as an analog to thm A in reference R, I have specific result or conjecture RC; Can anyone refer me to something resembling RC or a variant?" Here RC could be an affirmation of the points determined by geodesics for groups of prime power order, and is specific enough to get a response. I feel your post needs something that concrete and specific.