Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Facinating concept, but errors in text and some murky statements

I actually took a short course in this subject from the author at one of the JSMs. I immediately thought of some research possibilities, but had too much other work to follow up on them.I started to read this book a few years ago, but got bogged down with some examples, that I didn't have time to work through. Now that I am retired, I decided to go through the book again. I find the subject most interesting, and am now on page 66. However, I have found several errors in examples and some murky descriptions, which may be due to imprecise notation. (I'm still trying to figure one out.)