Raymond Smullyan presents a bombshell puzzle so startling that it seems
incredible that there could be any solution at all! But there is indeed
a solution -- moreover, one that requires a chain of lesser puzzles to
be solved first. The reader is thus taken on a journey through a maze of
subsidiary problems that has all the earmarks of an entertaining
detective story.This book leads the unwary reader into deep logical
waters through seductively entertaining logic puzzles. One example is
Boolean algebra with such weird looking equations as 1+1=0 -- a subject
which today plays a vital role, not only in mathematical systems, but
also in computer science and artificial intelligence.