I’ve been distributing the book in two parts, corresponding to content that is normally covered in our two semester sequence at UMass Lowell (Chapters 1-10 in Part 1- Fundamentals; Chapters 11-16 in Part II- Algebraic Structures). Not many people buy these print versions, but I prefer the lighter books. I don’t use them all that frequently since I tend to use html in class, but still use them to record typos (finally getting less frequent!) and making notes for improvements.

One of the nice things about PreTeXt is that it’s quite easy to create custom versions. If anyone would like some subset of the book in any format, let me know and I’ll create it. The only glitch I foresee is that if a reference is made to a non-included part of the text, a broken link will appear. I think that can be handled minimal extra work.

### Significant Additions in Version 3.5

Section 2.4: new exercises 5 and 6 on lattice paths

Section 5.1: added exercise 8 motivating the definition of matrix multiplication

Section 11.4: added exercise 11 on inverting a linear function.

New section: 12.6 Linear Equations over the Integers Mod 2