# What is a good basic reference on model categories?

I am looking for a general reference text on model categories, that contains all the basic results and definitions. I'm perfectly happy to be pointed towards a textbook, and I'm not looking for something with modern fancy theorems, just standard results. I know the definition of "model category", but not much else. I have some experience with one or two particular model categories, and I can prove any result I really need "by hand" for my particular examples, but much better would be to cite standard facts than to reprove special cases of them.

Here's the type of fact that I'd like to find in such a reference (if it is in fact true). By this I mean also that the reference should include all necessary definitions, since I'm not even sure how to make precise the following claim:

Suppose that $A$ is a cofibrant object, and $\hat B \to B$ is an acyclic fibration. For each $f: A \to B$, the space of lifts $\hat f : A \to \hat B$ covering $f$ is contractible.

The definition I know just guarantees that it is non-empty, but surely contractibility (if correctly defined) follows. Anyway, where can I find this and similar results? Something like "Model Categories for the working mathematician"?

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I really like the presentations in May's More Concise Algebraic Topology and Riehl's Notes on Categorical Homotopy Theory. The latter is freely available at math.harvard.edu/~eriehl/cathtpy.pdf –  Justin Hilburn May 28 '13 at 19:27
Thanks very much for the plug, but my coauthor's name, Kate Ponto, should be mentioned! (She was my student, and so was Emily Riehl). –  Peter May May 29 '13 at 3:05
I'm surprised that no one mentioned Quillen's original notes. They are amazingly well-written and a joy to read. The axioms may differ slightly from the modern ones but the proofs are the same. –  Adeel May 29 '13 at 9:27
Quillen's book is in fact mentioned in an answer below. –  Sean Tilson May 29 '13 at 17:51
If you want, you can also take a look at these notes: math.jussieu.fr/~vezzosi/seminar/notes.pdf, realized during a seminar organized this year by Gabriele Vezzosi. There might be mistakes, but they should also offer an overview of the theory (except for some more advanced results). (Beside that, if you find errors reading them, you can contact me freely) –  Mauro Porta Jun 14 '13 at 12:36

Hirschhorn's book, Model categories and their localizations, is a very thorough reference with many basic results explicitly stated and proved. The result you want is implied by axiom SM7 for simplicial model categories (see Proposition 9.6.1 in op. cit.), and for general model categories I suppose Corollary 16.5.4 is the closest analogue.

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For an introductory textbook I will recommend Homotopy theories and model categories by Dwyer and Spalinski. This 56-page paper is one chapter of the book "Handbook of algebraic topology" and gives a reader-friendly and comprehensive introduction to model category.

I think the book "Model Category" by Hovey, as tetrapharmakon and David has already recommended, is also very good and it contains some deeper results. However on the other hand it is a little bit more difficult to read (at least to me).

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I agree that Hirschhorn is very complete, but it can be hard to find things in it. That's why I'd recommend Model Categories by Hovey instead (it also seems a more canonical reference). It's written to maximize intuition for a (higher) category theorist, and focuses on developing a 2-category of model categories while simultaneously laying down all the basic theory in as concise a way as possible. Many people like this book because it strikes a good balance on the scale of readability vs. too-many-details. It manages to develop all the basic theory one would need and to contain all the major classical examples (including chain complexes and comodules over a Hopf algebroid, which don't seem to appear in Hirschhorn).

By the way, you should tell us what kind of application you have in mind. If you're interested in things like operads and algebras over an operad, then there are good arguments that what you really want are semi-model structures. In this case, the book Modules over Operads and Functors, by Benoit Fresse is very good.

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