@ArthurFischer Since you say that it is not that much work, I will ask what is preferred course of action when I see such a comment. a) flag; b) mention it in the office; c) let it be; d) any of the above.

(I mean preferred from the point of view of moderators.)

@MartinSleziak Either flagging or mentioning it here aren't terrible options. This seems to be more of a "Fischer Mods' Office" right now, so your audience may not be as large if you do use this room. If you see something that is breaking (the layout of) the site, I wouldn't just let it be, so (c) is out, and therefore (d), too.

Thanks for the answer @Arthur

Yes, you and Daniel Fischer are the mods with most messages in this room.

I don't recall whether I've seen other mods here.

Re: If you see something that is breaking (the layout of) the site, I wouldn't just let it be.

Until now I was somewhat hesitant to do this, since I thought it is not too easy. (I thought that it is needed to find the exact place with the invisible character appears.)

After your reply, I will probably flag or make a post here, when I see such thing.

@MartinSleziak I see that I should have also mentioned Jyrki Lahtonen there.

@MartinSleziak The invisible characters are added to the output, but not to the comment source itself (so when "rendering" the comment). Even if it were added to the source, one could copy that into some text editor, search and replace the invisible character(s) with nothing, and then add visible spaces in appropriate spots.

@AlexR If it is a contest problem, a cursory search couldn't find anything. Personally, I doubt that it is a contest problem (at least not from a "reputable" contest), since the first 100 terms could be literally anything. I would expect most (reputable) contests to ensure that there is a unique correct solution (or at least not infinitely many correct solutions), and not rely on "naturalness".

@SanathDevalapurkar I'll try to make sure that Pedro or Alexander see this. From my own look at the transcript, it appears that some comments were removed (and perhaps this is enough right now). If someone is constantly saying rude things to you, your best option, as FBR says, would be to ignore that user. If there are further concerns flagging specific chat messages and saying what's the problem might be a better route.

@SanathDevalapurkar Sanath, I read through some of the chat log around that time, as well as what you linked me just now, and though he is being weird I haven't seen anything that is actually defaming.

From what I can tell, he says that he knows who you are, and said your name. But this is the name on your user profile, so I am not sure that understand why this bothers you. If someone said they knew my name was Alexander, I would be rather unsurprised.

Has he engaged with you on any other occasions, or just that one?

@SanathDevalapurkar Sanath, this user has not said anything unfavorable as far as I can see. I was there when you engaged with him several times. In fact, I recall telling you not to pester him too much. You're both school companions, and it seems you know each other -- try to talk about this personally, perhaps?

When I say "pester", this is the context: I recall you pushing him to answer questions to you, to the point he'd get frustrated and uncomfortable. I recall telling him that you might have influenced him (in my opinion, badly) into trying to study certain things before he knew certain others. Is this bothering you, perhaps?

@ArthurFischer Note that copper.hat HAS found a natural solution and that some contests have "preliminary rounds" for a few weeks where problems can be solved from home with computer assistance. Also note that the same question was asked three times on the same day by different users, none with context. You'd at least have to admit there's something fishy about that.

@AlexR I don't doubt that there is a natural solution, but as that it a somewhat fuzzy concept I would expect most competitions to not rely on that to determine the correctness of an answer. (although 3,9,30,101,358,1443,1,1,1,1,1,1,1,1,1,... has a certain je ne sais quoi).

Even if it is fishy, without a publicly available exemplar there is little that can be done about this problem as it concerns our policy on on-going contests. I've done some searching in places that I suspect, but so far I haven't come up with anything.

@ArthurFischer I can assure you that copper.hat's solution is what appears to be the only "natural" solution and is natural in the sense that it doesn't involve any constants other than one single, small natural number.

Thanks for your time searching by the way :) I haven't found anything either so far, if nothing turns out over the upcoming week-end, I'll vote to re-open the question.

@ArthurFischer Revisiting the question: codechef.com/CDVA2015/problems/CDVA1501 is the source. This is an ongoing contest (no official one, but CodeChef is a programming contest site).

As a friendly reminder, I am still waiting to get a mod reply to the question below (at least the first part, perhaps the second is touchy)

@quid Rollback and/or flag. It's an edit that completely changes the question, so inappropriate. If it's just a user replicating something they have seen others do before, a rollback and a comment may suffice. If it's somebody doing it repeatedly, flag. I'm not quite sure how answers in comments should be handled.

Thanks @DanielFischer