# Is it acceptable to ask what are the pre-requisites of a book?

Sometimes I find an advanced mathematics book that does not state the pre-requisites in the preface or introduction. Is it acceptable to ask about them here? Perhaps someone could take a look at the book on Google books or Amazon and suggest something.

• With a bit of searching (e.g., google for prerequisites book site:math.stackexchange.com) you can find several such questions which were asked on math.SE. Of course, the site evolves and the fact that such questions have been well-received in the past does not mean that the same is still true. – Martin Sleziak May 28 '15 at 4:59
• Yes, it is quite acceptable, especially since authors have been known to lie about prerequisites, claiming that once you can differentiate $\sin(x)$ you can read their elementary book on the applications of $(\infty,2)$-categories to heterotic chiral perturbation in quantum chromodynamics . – Georges Elencwajg Jun 1 '15 at 11:27

I would say Yes to whether it is acceptable, in the sense that I will not vote to close it as off-topic, for the following reasons:

• The question is arguably about mathematics and its education.
• The question is precise and limited in scope.
• While people may have some minor differences in opinion, questions of this type is largely answerable with a more-or-less correct answer.
• Questions of this type seeks "expert knowledge".
• Questions of this type could be useful for others (other people looking to read the same text).

On the other hand, I do not guarantee such a question would be well-received. For books that have extensive reviews on Amazon or google, or for books whose publishers conveniently included such information on their website (but not in the book), I may down-vote the question because the asker did not do the basic homework.

Lastly, to ask about prerequisites is to ask for a person to have read the book and to have remember the details and to contemplate what is needed as a background, both technically and pedagogically, for approaching that book. This is not an easy question to answer.

An easier question to answer would be:

I am reading so-and-so's book such and such. In Chapter 3 I ran into an unfamiliar concept X. Can someone point me to in which subject X comes up and is taught and perhaps recommend a good book on that subject if my goal is to learn the theory discussed in such and such?

In other words, you don't always have to learn mathematics forwards. As a popular legend goes Hobbes learned geometry by reading Euclid backwards. A big chunk of self-learning is adapting to handle situations like this (don't click "next", click on the image).

• I agree with the point about asking specific questions but disagree with downvoting because a book has extensive reviews on Amazon. I have in mind anything beyond highschool textbooks or calculus. There's a lot of reviews to shift through and I think the community here would offer a better opinion than on Amazon. – abnry Jun 3 '15 at 0:41
• In support of @nayrb : Look at amazon.com/… That is a good book, most of the reviews are by students who obvioulsy hated it and learn you nothing about the books, a lot about what some students (dis)like. – kjetil b halvorsen Jun 3 '15 at 14:04
• @kjetilbhalvorsen: what does student like and dislikes have to do with a question about pre-requisites? In other words: if none of the reviews says anything about prerequisites, of course I will not count it against the OP. But if a large number of the reviews are of the form: "I am a second year graduate student and have studied subjects A, B, and C; and still I find the book incomprehensible." Then I would say that there gives some lower bound on the prerequisites. – Willie Wong Jun 3 '15 at 15:40
• @nayrb: perhaps what is not clear is my choice of the word "extensive". I meant it in the sense of "exhaustive, substantial, and thorough." The word "reviews" is in plural because I trust the opinions of several more than I trust that of one. Whereas you are thinking "many (possibly superficial) reviews" I intended "several detailed reviews" which, of course, will include information concerning prerequisites and such. – Willie Wong Jun 3 '15 at 15:47