The Right to Roam This walk across private land was not unusual. Thousands of distance walkers in Britain, regularly do the same thing , which is different from what people typically do in the United States. If you wanted to walk across America, you’d have to do it on a combination of public trails and roads and you certainly couldn’t cut across Madonna’s property. In the United Kingdom, the freedom to walk through private land is known as “the right to roam.” The movement to win this right was started in the 1930s by a rebellious group of young people who called themselves “ramblers” and spent their days working in the factories of Manchester, England. Katie Mingle, 99% Invisible 99percentinvisible.org walkingownershipland
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