Amazon calculates a product’s star ratings based on a machine learned model instead of a raw data average. The model takes into account factors including the age of a rating, whether the ratings are from verified purchasers, and factors that establish reviewer trustworthiness.
I purchased this book as it was required for a class. The book presents a lot of material and a lot of very practical considerations. At first glance, it seems like a very good resource because of all the topics it covers and integrates in the exercises.
That said, I've only read portions of five chapters and have found numerous rather conspicuous errors in both the text and the exercise sets. Some errors involve misrepresentation of k-map covers and demorgan's law; others in the exercise sets aren't so blatantly obvious. If i hadn't already covered this material in classes years ago, i'd certainly be confused. If you need to buy this book for a class, keep this hazard in mind if you ever get stumped.
A'B'+C'D' does not equal A'+B'+C'+D' (A+B+C+D)' does not equal A'+B'+C'+D' A+A'B does not equal A A xor B xor C does not equal AB+AC+BC these are just the ones i can recall from memory