My question https://math.stackexchange.com/questions/411987/collatz-like-5-x-pm-1-3 has been closed as "not a real question". I agree the question was insufficiently definite, and am grateful to the moderators and commenters (and to the person who added good math formatting to my post).

Actually rather than pose a new question, I had wished to introduce the 5n±1/3 Collatz-like function as a sub-comment under user Quanta's own, at question The $5n+1$ Problem

I could not find how to add my comment there however! I can see links/buttons to "edit" and to "reply", nothing to "add" a comment ! Is it really impossible to add new comments to the discussion at (non closed) questions, maybe, after some determined time, or am I just too dumb & missing something ?

I still am of the opinion than my variant has special "merits" beyond being one of an infinite class of Collatz-like iterations. I'd be glad if you helped me find the most proper way to have it introduced and discussed.

If it is not possible to add a short comment under Quanta's at the question mentioned above, then alternatively am I allowed to try to reformulate my closed "question" so it is shorter and avoids the vagueness criterion ? How am I supposed to submit a question so revised ?

• User having less than 50 reputation points can only comment on their one posts, see privileges. – Martin Sleziak Jun 6 '13 at 10:40
• Aha! Yet commenting seems most appropriate a way for adding information to, or asking clarification about a previous comment by another user. Doing so as if in answer to the original Question does not seem to be a proper option, does it ? What options are staying open, chat is it ? – NimbUs Jun 6 '13 at 11:28
• What to do if you want to comment and you do not have sufficient rep? You can post it as an answer; which will probably be deleted by a moderator and converted to a comment. (You can explicitly mention that you are posting an answer because you do not have sufficient rep to comment.) See help on deleted answer. IMHO a better solution would be trying to earn some reputation points, so that you can comment; if you can think of some way to earn rep. – Martin Sleziak Jun 6 '13 at 11:54
• The software is telling you NOT to add your question as a comment to another question. (Instead, improve your own closed question.) The reason for the limitation on comments is exactly this: new users often want to use comments inappropriately before they understand the workings of the site (and other stackexchange sites). – GEdgar Jun 6 '13 at 12:38

[A]m I allowed to try to reformulate my closed "question" so it is shorter and avoids the vagueness criterion?

Yes. From the Help Center | Closed Questions:

Closed questions cannot be answered, but are eligible for improvement (and eventual re-opening) through editing, voting, and commenting. See How to Ask for guidance on editing your question to improve it.

Another topic in Help Center | Reopen Questions is also relevant.

I had wished to introduce the $5n\pm 1/3$ Collatz-like function as a sub-comment

Introducing questions as comments is not effective (hardly anyone will notice) and may even be considered as an inappropriate use of the site. Inexperienced users are blocked from adding comment on posts other than their own, partly to prevent them from making such mistakes.

• I guess this post is also worth mentioning when talking about reopening questions: Requests for Reopen Votes. – Martin Sleziak Jun 6 '13 at 11:09
• @user79365 : "Introducing questions as comments is not effective..." Probably not. But please notice that the discussion we are having stems from my desire to introduce a (set of) problems, which (by moderator judgement) has been deemed NOT a question ! Hence, a comment. But I'm barred from adding comments, is this not what in English they call a catch-2-2 situation ? – NimbUs Jun 6 '13 at 11:34
• @NimbUs: What do you mean by "by moderator judgement"? Moderators are distinguished by diamonds next to their user names (see mine at the end of this comment). No moderators were involved in the closing of your question, only users with sufficient privilege. – user642796 Jun 6 '13 at 11:38
• @A.Fischer : my bad then, I misused the word moderator, having in mind such users with sufficient privilege as are permitted to close - or is it, request closure ? Never mind... – NimbUs Jun 6 '13 at 13:57