Do not explain too much It is seldom advisable to tell all. William Strunk Jr. & E.B. White, The Elements of Style secrets
To hide or dissemble Fact: The birth agonies of the New IRS led to one of the great and terrible PR discoveries in modern democracy, which is that if sensitive issues of governance can be made sufficiently dull and arcane, there will be no need for officials to hide or dissemble, because no one not directly involved will pay enough attention to cause trouble. David Foster Wallace, The Pale King secretsgovernment
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