Mathematical theory of program correctness

by J. W. de Bakker

"The third novel in Terry Pratchett and Stephen Baxter's "Long Earth" series, which Io9 calls "a brilliant science fiction collaboration.""-- 2040-2045. In the years after the cataclysmic Yellowstone eruption there is massive economic dislocation as populations flee Datum Earth to myriad Long Earth worlds. Sally is contacted by her long-vanished father and inventor of the original Stepper device, Willis Linsay. He tells her he is planning a fantastic voyage across the Long Mars and wants her to accompany him. U. S. Navy Commander Maggie Kauffman has embarked on an incredible journey of her...

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