I'm trying to understand the Homotopy Type Theory book. I find myself completely lost in Chapter 2, especially when it starts using higher groupoids.
What is the recommended background for this book? I once studied abstract algebra (and even remember a bit) same with topology, but not category theory. I skimmed a topology book recently to refresh my memory, but I'm realizing that the topology in the HoTT book is algebraic topology and I haven't studied that before.
My general question how can I fill the gaps in my background knowledge so that I can make sense of this book?
More specifically for Chapter 2, what is a good introduction to higher groupoids? Should I expect to learn about those by studying algebraic topology or category theory?
Your question was asked in October, so maybe you no longer need help... but for anyone who does, I highly recommend Bob Harper's video lectures on HoTT. (Which are from a graduate research seminar he taught at Carnegie Mellon. Lecture notes and hw problems are also available. The course was offered in the Computer Science department and there aren't really any pre-requistes aside from basic mathematical maturity. No need to study algebraic topology or category theory beforehand.) http://www.cs.cmu.edu/~rwh/courses/hott/