Have a deep view into what people are curious about.

🔗 Writing systems

A lipogram (from Ancient Greek: λειπογράμματος, leipográmmatos, "leaving out a letter") is a kind of constrained writing or word game consisting of writing paragraphs or longer works in which a particular letter or group of letters is avoided. Extended Ancient Greek texts avoiding the letter sigma are the earliest examples of lipograms.

Writing a lipogram may be a trivial task when avoiding uncommon letters like Z, J, Q, or X, but it is much more challenging to avoid common letters like E, T, or A in the English language, as the author must omit many ordinary words. Grammatically meaningful and smooth-flowing lipograms can be difficult to compose. Identifying lipograms can also be problematic, as there is always the possibility that a given piece of writing in any language may be unintentionally lipogrammatic. For example, Poe's poem The Raven contains no Z, but there is no evidence that this was intentional.

A pangrammatic lipogram is a text that uses every letter of the alphabet except one. For example, "The quick brown fox jumped over the lazy dog" omits the letter S, which the usual pangram includes by using the word jumps.

🔗 Mathematics

The expression "casting out nines" may refer to any one of three arithmetical procedures:

• Adding the decimal digits of a positive whole number, while optionally ignoring any 9s or digits which sum to a multiple of 9. The result of this procedure is a number which is smaller than the original whenever the original has more than one digit, leaves the same remainder as the original after division by nine, and may be obtained from the original by subtracting a multiple of 9 from it. The name of the procedure derives from this latter property.
• Repeated application of this procedure to the results obtained from previous applications until a single-digit number is obtained. This single-digit number is called the "digital root" of the original. If a number is divisible by 9, its digital root is 9. Otherwise, its digital root is the remainder it leaves after being divided by 9.
• A sanity test in which the above-mentioned procedures are used to check for errors in arithmetical calculations. The test is carried out by applying the same sequence of arithmetical operations to the digital roots of the operands as are applied to the operands themselves. If no mistakes are made in the calculations, the digital roots of the two resultants should be the same. If they are different, therefore, one or more mistakes must have been made in the calculations.

🔗 Food and drink 🔗 Plants

Ensete ventricosum, commonly known as enset or ensete, Ethiopian banana, Abyssinian banana, and false banana, is an herbaceous species of flowering plant in the banana family Musaceae. The domesticated form of the plant is only cultivated in Ethiopia, where it provides the staple food for approximately 20 million people. The name Ensete ventricosum was first published in 1948 in the Kew Bulletin, 1947, p. 101. Its synonyms include Musa arnoldiana De Wild., Musa ventricosa Welw. and Musa ensete J.F.Gmel. In its wild form, it is native to the eastern edge of the Great African Plateau, extending northwards from South Africa through Mozambique, Zimbabwe, Malawi, Kenya, Uganda and Tanzania to Ethiopia, and west to the Congo, being found in high rainfall forests on mountains, and along forested ravines and streams.

🔗 Statistics

Extreme value theory or extreme value analysis (EVA) is a branch of statistics dealing with the extreme deviations from the median of probability distributions. It seeks to assess, from a given ordered sample of a given random variable, the probability of events that are more extreme than any previously observed. Extreme value analysis is widely used in many disciplines, such as structural engineering, finance, earth sciences, traffic prediction, and geological engineering. For example, EVA might be used in the field of hydrology to estimate the probability of an unusually large flooding event, such as the 100-year flood. Similarly, for the design of a breakwater, a coastal engineer would seek to estimate the 50-year wave and design the structure accordingly.

🔗 Technology 🔗 Computing 🔗 Computing/Early computers

The Water Integrator (Russian: Гидравлический интегратор) was an early analog computer built in the Soviet Union in 1936 by Vladimir Sergeevich Lukyanov. It functioned by careful manipulation of water through a room full of interconnected pipes and pumps. The water level in various chambers (with precision to fractions of a millimeter) represented stored numbers, and the rate of flow between them represented mathematical operations. This machine was capable of solving inhomogeneous differential equations.

The first versions of Lukyanov's integrators were rather experimental, made of tin and glass tubes, and each integrator could be used to solve only one problem. In the 1930s it was the only computer in the Soviet Union for solving partial differential equations.

In 1941, Lukyanov created a hydraulic integrator of modular design, which made it possible to assemble a machine for solving various problems. Two-dimensional and three-dimensional hydraulic integrators were designed.

In 1949–1955, an integrator in the form of standard unified units was developed at the NIISCHETMASH Institute. In 1955, the Ryazan plant of calculating and analytical machines began the serial production of integrators with the factory brand name “IGL” (russian: Интегратор Гидравлический Лукьянова - integrator of the Lukyanov hydraulic system). Integrators were widely distributed, delivered to Czechoslovakia, Poland, Bulgaria and China.

A water integrator was used in the design of the Karakum Canal in the 1940s, and the construction of the Baikal–Amur Mainline in the 1970s. Water analog computers were used in the Soviet Union until the 1980s for large-scale modelling. They were used in geology, mine construction, metallurgy, rocket production and other fields.

Currently, two hydraulic integrators are kept in the Polytechnic Museum in Moscow.

🔗 Computing 🔗 Computing/Software

dwm is a dynamic, minimalist tiling window manager for the X Window System that has influenced the development of several other X window managers, including xmonad and awesome. It is externally similar to wmii, but internally much simpler. dwm is written purely in C for performance and security in addition to simplicity, and lacks any configuration interface besides editing the source code. One of the project's guidelines is that the source code is intended to never exceed 2000 SLOC, and options meant to be user-configurable are all contained in a single header file.

🔗 Computing

Better Portable Graphics (BPG) is a file format for coding digital images, which was created by programmer Fabrice Bellard in 2014. He has proposed it as a replacement for the JPEG image format as the more compression-efficient alternative in terms of image quality or file size.

It is based on the intra-frame encoding of the High Efficiency Video Coding (HEVC) video compression standard. Tests on photographic images in July 2014 found that BPG produced smaller files for a given quality than JPEG, JPEG XR and WebP.

The format has been designed to be portable and work in low memory environments, and used in portable handheld and IoT devices, where those properties are particularly important. Current research works on designing and developing more energy-efficient BPG hardware which can then be integrated in portable devices such as digital cameras.

While there is no built-in native support for BPG in any mainstream browsers, websites can still deliver BPG images to all browsers by including a JavaScript library written by Bellard.

🔗 United States 🔗 Comedy 🔗 Politics 🔗 Politics/American politics 🔗 Journalism 🔗 Politics/Gun politics

"'No Way to Prevent This', Says Only Nation Where This Regularly Happens" is the title of a series of articles perennially published by the American news satire organization The Onion satirizing the frequency of mass shootings in the United States and the lack of action taken in the wake of such incidents.

Each article is about 200 words long, detailing the location of the shooting and the number of victims, but otherwise remaining essentially the same. A fictitious resident—usually of a state in which the shooting did not take place—is quoted as saying that the shooting was "a terrible tragedy", but "there's nothing anyone can do to stop them." The article ends by pointing out that the United States is the "only economically advanced nation in the world where roughly two mass shootings have occurred every month for the past eight years," and that Americans view themselves and the situation as "helpless".

🔗 Robotics

Q-learning is a model-free reinforcement learning algorithm to learn a policy telling an agent what action to take under what circumstances. It does not require a model (hence the connotation "model-free") of the environment, and it can handle problems with stochastic transitions and rewards, without requiring adaptations.

For any finite Markov decision process (FMDP), Q-learning finds an optimal policy in the sense maximizing the expected value of the total reward over any and all successive steps, starting from the current state. Q-learning can identify an optimal action-selection policy for any given FMDP, given infinite exploration time and a partly-random policy. "Q" names the function that returns the reward used to provide the reinforcement and can be said to stand for the "quality" of an action taken in a given state.

🔗 Chess

Los Alamos chess (or anti-clerical chess) is a chess variant played on a 6×6 board without bishops. This was the first chess-like game played by a computer program. This program was written at Los Alamos Scientific Laboratory by Paul Stein and Mark Wells for the MANIAC I computer in 1956. The reduction of the board size and the number of pieces from standard chess was due to the very limited capacity of computers at the time.

The program was very simple, containing only about 600 instructions. It was mostly a minimax tree search and could look four plies ahead. For scoring the board at the end of the four-ply lookahead, it estimates a score for material and a score for mobility, then adds them up. Pseudocode for the chess program is described in Figure 11.4 of Newell, 2019. In 1958, a revised version was written for MANIAC II for full 8×8 chess, though its pseudocode was never published. There is a record of a single game by it, circa November 1958 (Table 11.2 of Newell, 2019).