It used to be that a mathematical proof meant absolute certainty. But today's proofs often are so long and complex that it's practically impossible for anyone to read one, let alone verify it. Thomas ...

Cannonballs and tomatoes -- The puzzle of the dozen spheres -- Fire hydrants and soccer players -- Thue's two attempts and Fejes-Tóth's achievement -- Twelve's company, thirteen's a crowd -- Nets and ...