I have a large knowledge of math books, due to spending an enormous amount of my free time in college in the math library and reading books that I downloaded.

I often will answer questions by people looking for book recommendations, but I wasn't sure if it was ok to mention that a certain book which is in print and sold in stores is easily available to download in one of the big math/physics books packages using BitTorrent.

What is the policy regarding this sort of thing?


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    $\begingroup$ I'd recommend just mentioning that it's on a torrent, and just let the interested user(s) search for it themselves. Google isn't that hard to use! $\endgroup$ Commented Nov 30, 2010 at 14:51
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    $\begingroup$ That's what I thought but I wasn't sure if even that was frowned upon. $\endgroup$ Commented Nov 30, 2010 at 14:54

4 Answers 4


I'd recommend against even mentioning that it is on a torrent. People with no moral qualms with this kind of thing will already be proficient enough to know where the look without you telling them, and will search whether you tell them or not. People with moral qualms will be uneasy at that additional bit of information.

I find it much, much more useful for an answerer to instead link to the GoogleBook page (or something similar) of the book in question: it saves you time from typing in the whole bibliographic information, and provide a way to possibly see previews of the text in question.


Posting overt torrent information can actually help the copyright owner more than the pirates, who can usually locate a download without any special hints.

Math books are small files and individual book torrents seem to be less common than collections of hundreds of books. An individual author or publisher may not have the time to search all the torrent sites one by one for specific books. However, a direct pointer, naming the book and the torrent site, on a site with high page-rank like MO or math.SE, would come up quickly in a web search. A publisher or owner of multiple works could use automated scripts (e.g., acting on RSS feed from math sites) to harvest such violations and refer them to the relevant enforcement entities. Posting torrent information accelerates the natural processes that would occur, slightly for the pirates but maybe radically for the owners of the works.


In the United States and other countries there is a legal concept called Fair Use under which the distribution of copyrighted materials is permitted. There is no reason to assume that a person downloading a book is not following these guidelines. This is the theory by which Google is able to provide free books although sometimes these are limited to excerpts due to agreements Google has made with publishers. Typically publishers do not own the actual copyrights but are authorized to enforce them, sometimes only implicitly. Copyright infringement is a criminal offense but most of the enforcement structure is of a civil nature which is often insensitive to fair use. I don't see a difference between a torrent and any other type of link: in either case if SE administrators receive a valid DMCA takedown notice from the copyright owner or some other legal mandate it will be removed; and it would be absurd to require that a person posting a link must first secure a distribution license.


I have a different opinion on this.

I understand that providing direct links to books can be problematic, as suggested in this answer.

What about comments like this. (The first one is similar to some comments I've seen here - but I've reworded it substantially, I hope the rewording was sufficient to make difficult to find the original comment and the identity of the poster of this comment. This comment is more-or-less in the spirit of J.M.'s comment above. The second one is basically the same as a comment I've posted a while ago and then deleted after I found this thread. I've changed this only to a book that is legally available online.)

  • This book might be downloadable in the electronic form from the usual places.
  • It seems that some copies could be found in the Internet, as Google search for "graph theory" diestel djvu or "graph theory" diestel torrent suggests. But there is no doubts that these copies are not legal. (Also you should be careful when using the sites like this, because of viruses and stuff.)

I am far from being legal expert, but I have hard time imagining that posting a link to results of Google search might be illegal. So I think the only problem is whether MSE community would object to something like this on moral grounds.

Of course, I will follow community consensus on this issue. (As the moment when I am posting my answer, Willie's answer has 19 upvotes so it seems to be the general opinion. I wanted to provide an alternative viewpoint.)

  • $\begingroup$ Perhaps I should add that if there should be a problem with the links that I posted, I am willing to repost the answer again (so that they are not visible even in the edit history, of course 10k+ users will still see this). The links are to a Google search for copies of a book that is legally available, but I can imagine that some people might have a problem with the kind of websites that came up as results in the search. $\endgroup$ Commented Aug 18, 2012 at 7:50

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