Reflections on Software Performance An Article by Nelson Elhage blog.nelhage.com Performance is a feature Performance changes how users use software Performance needs effort throughout a project’s lifecycle Architecture strongly impacts performance Performance isn’t just about hot spots Performant foundations simplify architecture …we underrate performance when designing and building software. We have become accustomed to casually giving up factors of two or ten or more with our choices of tools and libraries, without asking if the benefits are worth it. performancesoftware
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