The drift The Situationists were also practitioners of a special urban-analytic walking style, the dérive—the “drift”—which Debord described as “a technique of transient passage through varied ambiences. The dérive entails playful-constructive behavior and awareness of psychogeographical effects; which completely distinguishes it from the classical notions of the journey and the stroll.” “In a dérive,” Debord deadpans, “one or more persons during a certain period drop their usual motives for movement and action, their relations, their work and leisure activities, and let themselves be drawn by the attractions of the terrain and the encounters they find there." The dérive joins the free association of surrealism, the LSD of hippiedom, and cinematic montage as tactics for overcoming the fixity of received ideas of order and logic. By putting progress through the city into a state of constant indeterminacy, it represents a schooled “style” of being lost. Michael Sorkin, 20 Minutes in Manhattan PsychogeographyRaindrops leaving an erratic trail psychologymovement
The axis of movement Moving in the city means constantly changing the axis of movement. In general, lateral movement is confined to a single plane, what’s called grade, the ground level. Because circulation in multistory buildings is fundamentally one way—which is to say from the bottom up—the condition at the top is invariably different from that at the bottom. Rooftop circulation is the domain of Fantômas, of cat burglars and fleeing criminals, of lovers, and of those acrobatic enough to negotiate the gaps between buildings. Michael Sorkin, 20 Minutes in Manhattan A Burglar's Guide to the City movement
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