Slow progress again but, as I said before, any progress is better than none. So here are Chapters 1 to 9 of Beginning Category Theory. [As always you may need to force a reload to get the latest version.]
And no, there isn’t really a new chapter. I’ve split what was becoming a baggy chapter about kinds of arrows into two, and I hope to have made some of it a fair bit clearer and better organised. The chapters are
- Introduction [The categorial imperative!]
- One structured family of structures. [Revision about groups, and categories of groups introduced]
- Groups and sets [Why I don’t want to assume straight off the bat that structures are sets]
- Categories defined [General definition, and lots of standard examples]
- Diagrams [Reading commutative diagrams]
- Categories beget categories [Duals of categories, subcategories, products, slice categories, etc.]
- Kinds of arrows [Monos, epics, inverses]
- Isomorphisms [why they get defined as they do]
- Initial and terminal objects
Ch. 3 has been mildly revised again, and as I said Ch.7 has been significantly improved. Various minor typos have been corrected. And there have been quite a few small stylistic improvements (including, I’m embarrassed to say, deleting over 50 occurrences of the word “indeed” …).
2 thoughts on “Beginning Category Theory: Chs 1 to 9”
Possible typo: Top of page 47 you define objects of a slice category as arrows f: A -> I but the diagram shows the target as C
Thanks, a definite typo! Now corrected.