Discrete Mathematics (6th Edition) (Jk Computer Science and Mathematics) (Hardcover)

There is no clear line of exposition in this book. Knowing what it should be about, it is repulsive to see how unstructured the content is, and how truly beautiful mathematics is made ugly beyond recognition. There exist far more insightful and shorter proofs than many of those given here.

Instead of developing a choice of key topics cleanly, transparently, and in detail, a large collection of loosely related facts are glued together in a supremely uninspired way. Some topics which are far too advanced for this level of exposition are mentioned over several pages, without any rigorous treatment, of course, while many important topics are left away that could have been included.

The elegance quotient of this book is zero. Students should learn how to present a proof. They should learn to pin down the key ideas, and to write a proof in the clearest and most transparent language as possible. Whoever takes this text as her/his stylistic guide will do her/himself great harm.

I am a research mathematician. It is my job to know precisely what good mathematics looks like, and also to know when something smells really bad. Believe me, this one smells beyond rotten.

There are beautiful treatises on the same material on the internet, and one may also look at a small book for roughly 10 $ by Balakrishnan, from Dover publishers (available on Amazon, "Introductory discr math"). It doesn't contain as much material, but is so much more worth the money. A diligently made choice of topics is presented in clear, concise words that are to the point.

There is also the book by Laszlo Lovasz, a master of the field. The clarity, inspiration and transparence of the exposition is absolutely exemplary. The paperback version costs around 35$ on Amazon.

If you read those texts, you will understand what Johnsonbaugh is trying to put into clumsy words, illiterate proofs, boring examples, and silly pictures.

What really hurts me is to see students, some of whom are not rich, paying 100 $ for this convoluted mess.

My main message to every student using Mr. Johnsonbaugh's oeuvre is: If you don't understand this mess, it may be because you have mathematical talent. Go and look for a better, cheaper text. Save your time, it's not worth trying to figure out what the author intends to say.

This is, without a doubt, the WORST textbook I have EVER encountered -- in any subject. It might qualify as the worst textbook OF ALL TIME. Yes, it's really that horrible. It's verbose. It's dull. Many of the examples are longer than necessary (and more than occasionally, misleading). Like many texts on this topic, it features Solutions to Selected Exercises in the back, but what's the point in displaying the final answer to an involved problem if you don't demonstrate how you arrived at it? If you're going to print an answer, PLEASE provide us with the COMPLETE answer.

I have searched (largely in vain) for another text or two to use as study aids. If you're thinking about Schaum's, hang onto your money (Note to Schaum's: Why publish a separate book of "Solved Problems" if you're merely recycling the same examples from the Outlines book?). Susanna S. Epp's textbook is much better in most places -- most notably the section on graphs.

Bottom line: if your school adopts Johnsonbaugh as the required text for your course, hang onto your money and rely on your lecture notes. This book is a waste of trees.