The SciencesMathematical Recreations May 1991The theory of rigidity, or how to brace yourself against unlikely accidentsBy A. K. Dewdney on May 1, 1991AdvertisementABOUT THE AUTHOR(S)Recent Articles by A. K. DewdneyDIY Fractals: Exploring the Mandelbrot Set on a Personal ComputerPhotovoresTuring Test