This is one of the frequently occurring duplicates of questions like this.

Upvoted and answered PSQ.

duplicate I have voted to close this question as a duplicate. While old, it just attracted a fairly low quality answer. The question that I dupe-targeted has a much better answer.

Very low quality question

PSQ

PSQ2

PSQ3

PSQ4

@JoséCarlosSantos: Some of the D1 - D18 deletion candidates I posted at 11:36 are gone but quite a few remain (requiring 1 or 2 more votes). Thanks.

Also for deletion: D19, D20

... and D20 is quite remarkable

Astonishing

[ SmokeDetector | MS ] Bad keyword in link text in body (66): How does the contemporary field of logic/mathematics feel about using contradiction as a method of proving a conjecture? by tr3ndyBEAR on math.SE

@RRL Done.

@JoséCarlosSantos: Thanks again for going through all of that.

A few left now — perhaps others will take a shot at it.

@RRL All are gone.

delete 1, 2, 3, 4

delete 5, 6, 7, 8

delete 9, 10, 11, 12

delete 13, 14, 15, 16

Why does such a question has been removed by community bot ?

math.stackexchange.com/questions/3082672/…

I though community was removing only abandonned question, so I'm a bit surprised about this one.

@pilko As I understand it from meta.stackexchange.com/a/312594/196432, the Q&A (with positive votes on both question and answers) should not have been deleted. There might be other reasons (and I am purely speculating) that only moderators know about.

The answer linked by @MartinR seems to be about roomba. Questions deleted in this way are shown with the message "RemovedAbandonedClosed".

When I look at the timeline of the question I see the following: "deleted Community♦ User 637091 destroyed".

So it seems that this was made by some higher power (mods or SE employees) @pilko.

AFAICT this user did not made many post - older post would still be shown in SEDE, since the last update was made before the user was destroyed: data.stackexchange.com/math/query/942474/… data.stackexchange.com/math/query/942475/…

I'll copy here the most relevant part from the linked post:

> "Destroyed" users have all that, but have all of their posts deleted. It is intended for things like spammers, where we just want them to be gone. A user must have less than 500 reputation in order to be destroyed. Given that, it's up to the moderator to simply select "destroy" from the mod menu.

In any case, the question about $\int\frac{\sqrt{\cos2x}}{\sin x} dx $? seemed interesting to me. So maybe if somebody reposts the question in a better form, it might be useful - and perhaps this one can be merged into it, so that the answers are not lost.

Another option would be to undelete the question - but since it has basically no context other than "I have tried various substitutions", it might get closed and deleted anyway (PSQ/context). And since mods considered the user problematic enough to be destroyed, it's possible that undeleting the post would go against their intentions.

(It's not easy to say, since we do not know the exact reasons why the account was destroyed. But the linked post suggest that this is done only if there are some serious problems with the user.)

[ SmokeDetector | MS ] Blacklisted username (92): How many ways are there to place these books on the shelves? by Donald Trump on math.SE

@MartinSleziak A search with Approach0 shows that this integral has been treated before.

I should have searched... :-)

So we have the deleted post 3082672: Any help in solving $ \int\frac{\sqrt{\cos2x}}{\sin x} dx $?.

And the three older posts you found - 606251: Integrating $\int\frac{\sqrt{\cos 2x}}{\sin x}\,\text{d}x$., 876175: Evaluation of $\int\frac{\sqrt{\cos 2x}}{\sin x}\,dx$, 887082: Integral of $\frac{ \sqrt{\cos 2 x}}{\sin x}$.

So maybe some duplicate closures would be in order. And if the answers to the deleted one add something which is missing in the older duplicates, maybe it can be merged.

It seems quite a lot stuff to be checked (regarding choosing the best duplicate target and also possible merge) - I do apologize, but I won't have time for this right now...

close (Old) PSQ.

@Shaun It already has to reopen votes. :-(

@MartinSleziak thank you for your investigation. I just merged my answer to what appears to be the "main" post. In fact it was more interested by the how and what about community bot rather than the right to exists of this particular post.

@pilko Probably you mean "copied" rather than "merged".

Moderators can merge questions.

@JoséCarlosSantos I was one of those reopen votes. I do not think that there is any benefit to closing a question which is 3 years old. I edited the question a bit to improve it and to make it not a PSQ.

@pilko By "the main post" you mean that you would choose that one as the duplicate target? It is the question 876175: Evaluation of $\int\frac{\sqrt{\cos 2x}}{\sin x}\,dx$.

@user1729 improve If the question is being edited to a better form, perhaps adding link to the question showing that different order of three elements lead to the same order might by suitable addition: Let $G$ be a group. Show that $\forall a, b, c \in G$, the elements $abc, bca, cab$ have the same order..

I am a bit less sure whether to add also Example that in general $|abc|\neq |cba|$. (If we ignored the fact that it is proof-verification question, it would be a duplicate.)

Hi @AndrésE.Caicedo - it's quite rare to see you in chat :-)

I hope it's ok that I have edited the dead link in your answer a few days ago - I left a few comments in MO editors' lounge: chat.stackexchange.com/transcript/10243/2019/1/11 (If something more needs to be added regarding this, we can move there.)

@MartinSleziak That's a nice addition. Thanks. I saw your edit to the other post, on proof-verification/"$|abc|\neq |cba|$" and had wondered about closing the currently-closed one as a duplicate of this one. Perhaps it would make more sense now to close the proof-verification one as a duplicate, as it doesn't look like the proof-verification one will be useful to others, while the first question has at least 3 answers (of varying degrees of quality/detail).

I think I have only added a tag on that one.

To my surprise, I see that the question was reopened.

I am well aware that several users are against editing posts by other users to include context. OTOH in this case the OP is inactive for a long time. There have been many discussions about this on meta, perhaps quid's answer to this one (relatively recent - different topic but related) gives a reasonable summary: Historical lock for preserving old, low quality questions.

@MartinSleziak Yes, sorry, it was just a tag edit. I didn't mean to claim more :-) I've closed one as a duplicate of the other.

reopen This does have context.

( . . . although it is a duplicate.)

@Shaun duplicates It was reopened. Should it now be closed as duplicate? (Possible targets are 422318: if $A$ is Abelian group , $B$ is subgroup of $A$ , Is $B \times A/B \cong A$? or 321176: If $H$ is a normal subgroup of $G$, is $G/H \times H \cong G$?)

For deletion: D1, D2, D3, D4, D5, D6 , D7,D8

@MartinSleziak close Yeah, I guess so; I made a close vote now.

@Lord_Farin Most of these are still there.

close PSQ