on 3 June 2003
If you are new to Smullyan and his puzzles this book is not a bad place to start from. You will find a great deal of logic problems regarding truth-tellers and liars, such as: "Person A says that at least one of A and B is a liar (never tells the truth). Is A a liar? And what about B?". This is the simplest type of puzzle; many are much more challenging.
If you already read some of Smullyan's books, be assured that this one has the same appeal. Some of the knight-knaves puzzles are similar to the ones in "What is the name of this book?" and "Alice in puzzle-land" but there are important variations such as day-knights and night-knights and there is also some challenging metapuzzle.
The second half of the book leaves the island of knights and knaves to enter an enchanted forest of talking birds. Though I found this part somewhat difficult to get in, once you work carefully your way through the first chapter you will find it fascinating. At the end you will have solved a lot of interesting problems and explored a subject called combinatory logic which has important applications in modern logic. As Smullyan puts it, "what could be better for a puzzle book?"
on 5 January 2008
I enjoyed this book immensely, and if you like Smullyan's style, then you will too. However, I found some parts of it more difficult than other books I own by the same author. Perhaps the novice reader should choose a different book?
on 9 July 2015
One of the most remarkable and fun books I've ever worked through. This book teaches combinatory logic by masking combinators as singing birds. You'll be hearing Turing birds sing and you'll be traveling to Godel's forest. Make sure to be prepared for your journey with a lot of paper and tea as this book will capture you once you start working through the problems. You'll be laughing along the way as you discover new birds and your mind will stretch a lot. If you've patience to work through all the chapters, you'll learn about Church encoding and Godel's incompleteness theorem in the end.
This book is so fun that I've placed it #7 in my Top 100 Programming, Computer and Science books list:
(If this link gets removed, google for >>catonmat top 100 programming computer science books<< to find my article.)