We have updated the online version of the book to accept comments on a paragraph basis. Click on the link after a paragraph to comment on it. The comment will appear once the administrators validate it.
The goal of the comments is not only to find errata, but to build collaboratively a better, more useful text for the whole community. New developments, issues that need clarification or expansion, and questions, both specific and open-ended, are very welcome.
The authors will do their best to review timely, and give useful feedback when appropriate.