
> 
> Why aren't there any "crowdsourced" projects for mathematical textbooks?
> 
> 
> 


Every year, many mathematicians put a lot of effort into crafting their own lecture notes or writing textbooks (or also research monographs). Why aren't there any open-source "crowdsourced" cooperative efforts towards book writing? The pros of this kind of collaboration are rather obvious.



Polymath-type projects for textbooks?
The [Homotopy Type Theory](https://homotopytypetheory.org/book/) book is massively collaborative and regularly updated (through version control). It's also the definitive textbook in its field, and I think Voevodsky himself contributed to it. In particular, it is mentioned that:



> 
> We have released the book under a permissive Creative Commons licence
>  which allows everyone to participate and improve it.
> 
> 
> 


I've found it to be particularly well-written and comprehensible.


