"The book has 63 chapters, each one ... representing an edited version of a post in GLL. ... this book will appeal to readers seeking an insider view on how creative mathematical ideas emerge. And it will also appeal to experts for its insightful ruminations on current scientific and cultural problems in theoretical computer science." (Marius Zimand, Mathematical Reviews, June, 2015) "This book is one of those inspiring books that almost every computer scientist should read. Moreover, it is also very well suited to a wider audience, including those curious about the field and newcomers. Its authors, Lipton and Regan, did a wonderful job introducing and analyzing important problems in complexity theory with an easy-to-read text. ... It is therefore an invaluable source of inspiration and study." (Carlos Linares Lopez, Computing Reviews, August, 2014)