If it could save a person's life, would you find a way to make it faster? "If it could save a person's life, would you find a way to shave ten seconds off the boot time?" [Jobs] asked. Kenyon allowed that he probably could. Jobs went to a whiteboard and showed that if there were five million people using the Max, and it took ten seconds extra to turn it on every day, that added up to three hundred million or so hours per year that people would save, which was the equivalent of at least one hundred lifetimes saved per year. "Larry was suitably impressed, and a few weeks later he came back and it booted up twenty-eight seconds faster," Atkinson recalled. "Steve had a way of motivating by looking at the bigger picture." Walter Isaacson, Steve Jobs performancemotivation
Wang tiles Wang tiles (Hao Wang, 1961) are a class of formal systems. They are modelled visually by square tiles with a color on each side. A set of such tiles is selected, and copies of the tiles are arranged side by side with matching colors, without rotating or reflecting them. The basic question about a set of Wang tiles is whether it can tile the plane or not, i.e., whether an entire infinite plane can be filled this way. The next question is whether this can be done in a periodic pattern. In 1966, Wang's student Robert Berger solved the problem in the negative. He proved that no algorithm for the problem can exist, by showing how to translate any Turing machine into a set of Wang tiles that tiles the plane if and only if the Turing machine does not halt. The undecidability of the halting problem then implies the undecidability of Wang's tiling problem. Wikipedia en.wikipedia.org Truchet TilesThe Tiling Patterns of Sebastien Truchet and the Topology of Structural Hierarchy mathalgorithms