Do I really have to cite an arXiv paper?

Thanks - I remember reading about Perelman before but I didn’t realise the proof was unpublished.

I am astounded that people would question citing an arxiv paper. If you get an idea from somewhere else, you cite it. This doesn't even have to do with the archive. I have on multiple occasions read papers where the author wrote a proof and then cited "private communications" with another mathematician as the source. In a business where ideas are ideas, you should always cite the source. Anything else is extremely dishonest.

edit: To be clear, I am personally entirely okay with not citing papers containing ideas you were unaware of during your own formulation (though I think if you become aware of it, you should probably point out that it was previously independently discovered by someone else). Your paper may still have merit even if it's idea isn't "new" (especially if the first paper is shit as is often the case).

edit2: I personally don't see much wrong with Yoav Goldberg's blog post linked in this blog post. It's refreshing to hear his honest opinions out loud. As a graduate student I always lost a little sanity each time I read a paper with "great ideas", but terrible follow-through (i.e. explanation and proof of those ideas). I personally think that clarity of exposition is at least as (if not more) important than the novelty of an idea. However, you should still cite the sources of your ideas. Feel free to point out the source's flaws, but cite them nonetheless.

(Hopefully no more edits...)

In the academy it would be legitimate grounds for an academic misconduct case.

It's a bit tougher when a paper hasn't been peer reviewed, although not too different from a good paper published in a low quality or unknown conference. I think you should cite any idea you pick from a paper when the said paper has some the following qualities:

- novelty

- technical correctness

- clarity

- good experimental evaluation

Novelty is the most important: if without the citation your paper looks like the original idea, this is plagiarism.

If the paper has big shortcomings that your paper adresses, it is fair to give yourself the credit you deserve of course, but it doesn't harm to cite the other paper, in fact it gives a way to give some sort of peer review: In [1], Foo and al. attempted to explore but the experiments were inconclusive/the technique sucked compare to state of the art/they didn't explain how they did it... In this paper we did this and that and it gives us awesome results (Said in a nicer way)

>“Do I really have to cite arXiv papers?”, they whine. “Come on, they’re not even published!,” they exclaim.

Is this really a thing?

I understood that today you even city web pages (with a time stamp) and even your dog.