A few weeks ago Algorithms from the Book. was deleted, apparently by the owner. This was the top ranked answer for the question (Euclidean algorithm), and as of now would still be the top ranked answer. The user's name is now "deleted" and I assume the account was either accessed by a vandal, or the person decided to remove their contributions to CSTheory.

I think the response is worth preserving, and other responses refer to it. So I am tempted to copy the text into a new answer, and mention that the answer was originally posted by a person who has removed their profile. Alternately, the answer could be undeleted. Is there a consensus on the best way to proceed?

In my opinion, the fact that the poster deleted his/her post (possibly at the same time as deleting his/her account) should be respected. Therefore, I oppose to copy-and-pasting or undeleting the deleted answer, even if the answer was very good.

If you think that the answer was good, there is nothing wrong with restating it in your own words as a new answer, probably giving credit to the deleted answer. Quoting part of it may also be appropriate depending on the situation. Even if you quote part of it, the new answer should be yours, for which you are responsible.

• Well, if I understood the terms correctly, anything posted on the site is governed by cc-wiki license, so I don't see any problem in copying the answer. Not naming the user would be enough. Oct 24 '10 at 22:25
• @Kaveh: My answer has nothing to do with legality. If you are claiming that “if it is legal, there is no problem,” then I cannot agree. Oct 24 '10 at 22:45
• @Tsuyoshi: No, I am not saying that, but I don't think there is any reason not to copy it, the user hasn't said that he/she has a problem with reposting it. If there was a note by the OP in the post that explained the reason it has been deleted and OP does not want it to be reposted that would be different. Oct 24 '10 at 22:53
• @Kaveh: My opinion does not change: we should respect the fact that the poster deleted his/her answer. For me, the mere fact that he/she deleted it is a valid reason to avoid copying even a sentence from it, and no additional comment by the poster stating “do not repost” is needed to discourage me from copying. That said, as I wrote in my answer, quoting part of it may be appropriate depending on the situation. Oct 24 '10 at 23:07
• I agree with Tsuyoshi. I would respect the original poster and not post a part of it (unless really necessary). Feel free to to suggest the same algorithm as your own answer to that question, acknowledging the anonymous poster, if you wish. Oct 24 '10 at 23:08
• @Kaveh: I, too, agree with Tsuyoshi on this. If a user deletes something they posted, then their wishes should be respected and the post should not be undeleted or reposted. Oct 24 '10 at 23:45
• I don't care one way or the other frankly. Who knows why someone deleted something. If you like the answer, definitely repost it under your own name and attribute if you feel so inclined. Oct 25 '10 at 7:37
• @Suresh: Just in case, I am not personally interested in reposting this particular answer at all. Honestly speaking, the question “What are algorithms from the Book” is not so interesting to me. I just argued that if András wants to, he should repost it in his own words instead of undeleting or copy-and-pasting it. Oct 25 '10 at 10:35
• @Tsuyoshi, @Suresh: I am not really interested in reposting it either (I agree with Tsuyoshi's assessment of the question). Yet undeleting (the low-effort solution) seemed to be the wrong response. It seems a pity to leave the question with holes in the answers; this is a hazard to consider in future. Oct 26 '10 at 11:54

I wouldn't post this if I didn't think that this is going to create a bad example for future decisions. We are drawing lines about what is appropriate too strictly. We are being too conservative, the default position should be trusting decisions made by other users. If there is a disagreement, if the OP comes back and says I want this removed for some reasons, then we can discuss it, but as long as there is not a conflict, we should be very liberal about what users can do.

What are we going to do if a user copies a deleted answer and posts it? Are we going to down vote it? Are we going to delete it? What if a number of users undelete a post. The system permits other users to undelete posts, even if it is deleted by the OP. Are we going to punish the users for undeleting it? Are we going to delete it again?

I also don't see any reason legally or ethically for not copying an answer. What is the ethical principle that is being violated?

IMHO, copying answers is completely compatible with the philosophy of the site. Let me quote a part of FAQ:

Other people can edit my stuff?!

Like Wikipedia, this site is collaboratively edited, and all edits are tracked. If you are not comfortable with the idea of your questions and answers being edited by other trusted users, this may not be the site for you.

I think this is clear about the philosophy of SE. If you are not happy about copying answers, I respect your view. But if you are saying that it is inappropriate or unethical and/or if you are trying to draw lines too strictly about how other users or moderators should act, and about what is appropriate and what is not, sorry, but I don't agree.

Edit 10/26/2010

I agree with Tsuyoshi that there is not a need to agree on everything, i.e. I agree with Tsuyoshi to disagree.

My main point here is on how conservative we should be on what trusted users/moderators can do. My view, as I wrote above, is that we should trust decisions made by others and be very liberal, we don't need to discuss every decision made by others, unless there is a conflict/disagreement.

Let me also make it clear that there is a difference between being nice to others and what is ethical. An action can be considered "not being nice to others", but still don't violate any ethical principles. Being nice is boarder than being ethical (in this context).

Now, let me return to the particular case of this question. My sentence about the ethical principle being violated is in the context of our discussion, i.e. the appropriate use of this site. The argument, if I understood it correctly, is that we should respect the decision made by OP about deleting their post, and I guess this is based on the view that OP own what they have posted. I am not sure I agree with this. Again if I understood the philosophy of the site correctly, it is very similar to Wikipedia, and it is a collaborative effort. If you have posted something, others can modify, edit, or even copy-and-post it.

Some discussion on why it is not clear to me if a post is owned by OP, specially a CW post:

I. When someone posts an answer/questions, it means that other users are probably going to avoid posting similar content,

II. People vote for the answer,

III. Other answers may refer to it.

Removing a post can also be considered as not respecting the questioner, other user answering the question, and the votes given to the answer.

Now, if it is CW, i.e. community wiki, it is more involved.

IV. CW answers are owned by community, they are edited by other users, and removing a post can cause even more problems in this case.

Assume that we have a CW question about what is the most famous problem in TCS, and someone posts "$$P$$ vs $$NP$$", and of course receive lots of votes, after a few months the OP goes back and removes the answer. Assume that no one notices this. Think how it would look like if someone from outside or a new user reads the question and does not see an "$$P$$ vs $$NP$$" answer?! And even if another users posts it again, how many times do other uses have to vote for the same answer? Should we expect them to vote once every time someone removes it and someone else reposts an answer which is essentially the same?

I suggest you read this post: What can cause a post to be deleted, and what does that actually mean?

In particular, this part:

When can't I delete my own post?

You can't delete your question if it has more than two answers, if an answer has a score >= 2, or it has been closed less than 48 hours ago.

There are restrictions on when an answer can be removed by OP.

In summery,

I. it is not clear to me that OP owns what they post, specially CW posts,

II. deleting a good highly-voted post by OP (without stating any reasons) can also be considered disrespect towards other users, and may cause problems.

Just to make it clear, I agree that we should be nice to others, and if the OP complains about undeleting their post (and states some reasons for it) I would support the OP, but IMO, the default position should be that "posts can be undeleted by others, even if OP have removed it", specially if they are good and highly-voted.

• “I also don't see any reason legally or ethically for not copying an answer. What is the ethical principle that is being violated?” In my answer, I wrote an ethical reason not to copy from a deleted answer. I thought that you understood it and disagreed. But if you do not even understand it, I do not know how to explain it to you anymore. Oct 25 '10 at 10:47
• @Tsuyoshi: My take on this question is that we are debating the ethics of this site. Possibly this is the primary purpose of beta. Kaveh has a valid point by quoting from the FAQ that "our" ethics (well, those of our SE overlords) permit edits, of which answer resurrection is just one example. Whether we agree with this is each of our own prerogatives.
– RJK
Oct 25 '10 at 11:27
• @RJK: I agree (assuming that you meant Meta instead of beta, but this is a very minor point). Just in case, I am not asking Kaveh to agree with me. I am just asking him/her not to neglect the fact that I gave an ethical reason to avoid copying. Except for this, I am happy with this discussion because we have at least clarified the difference of opinions. Oct 25 '10 at 11:58
• Btw, if there is a strong consensus in the community on adopting some rule like "others should not undelete a post deleted by OP", then I think we can have it as a part of our own policy, i.e. we can have differences with the general philosophy of SO/SE. (SO/SE overloads say that the communities run the sites, not them; so I don't think it would be difficult to get their agreement if required.) Oct 26 '10 at 8:31