Beginning Category Theory: Chs 1 to 13 (etc.)

Here are the revised Chapters 1 to 13 of Beginning Category Theory — together in one PDF with the remaining unrevised chapters from the 2015/2018 Gentle Intro. [As always you may need to force a reload to get the latest version, dated April 18.]

So, the updated chapters are now these:

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 objectsPairs and products, pre-categorially [Motivational background]Categorial products introduced [Definitions, examples, and coproducts too]Binary products explored [A few more techie results]Products more generally [Ternary, more finite products, infinite products]

Since the last posting, Chapter 10 has had very minor tinkering. Chapter 11 is, however, improved and expanded (pulling a few more interesting things from what was the following chapter). That leaves a few somewhat fiddly results for the short Chapter 12  (some will be used later, and others give a bit of practice with characteristic styles of argument — but really at this point you can skip this!). And now results about finite products and infinite products more generally are separated out from that more boring stuff to become their own Chapter 13.

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