Permutation City is a science fiction novel by Greg Egan that explores various philosophical aspects of artificial life and simulations of intelligence. It won the John W. Campbell Award for the best science-fiction novel of the year in 1995 and was cited in a 2003 Scientific American article on multiverses.

Warning: Wikipedia contains spoilers.

Permutation City asks many of the same kinds of philosophical questions as The Matrix, Blade Runner and Ghost in the Shell -- does anything differentiate a perfect computer simulation of a person from a "real" one? -- but its textual nature allows it to push the ideas further. Egan gleefully deconstructs and undermines traditional notions of self, future, personality, and even physical reality.

A loose sequel, Diaspora was published in 1997.

Its ISBN number is ISBN 1-85798-218-5.