New Articles (Page 286)

To stay up to date you can also follow on Mastodon.

๐Ÿ”— Bernoulli discovered e by studying a question about compound interest

๐Ÿ”— Mathematics

The number e is a mathematical constant approximately equal to 2.71828 and is the base of the natural logarithm: the unique number whose natural logarithm is equal to one. It is the limit of (1 + 1/n)n as n approaches infinity, an expression that arises in the study of compound interest. It can also be calculated as the sum of the infinite series

e = โˆ‘ n = 0 โˆž 1 n ! = 1 1 + 1 1 + 1 1 โ‹… 2 + 1 1 โ‹… 2 โ‹… 3 + โ‹ฏ {\displaystyle e=\sum \limits _{n=0}^{\infty }{\frac {1}{n!}}={\frac {1}{1}}+{\frac {1}{1}}+{\frac {1}{1\cdot 2}}+{\frac {1}{1\cdot 2\cdot 3}}+\cdots }

The constant can be characterized in many different ways. For example, it can be defined as the unique positive number a such that the graph of the function y = ax has unit slope at x = 0. The function f(x) = ex is called the (natural) exponential function, and is the unique exponential function equal to its own derivative. The natural logarithm, or logarithm to base e, is the inverse function to the natural exponential function. The natural logarithm of a number k > 1 can be defined directly as the area under the curve y = 1/x between x = 1 and x = k, in which case e is the value of k for which this area equals one (see image). There are alternative characterizations.

e is sometimes called Euler's number after the Swiss mathematician Leonhard Euler (not to be confused with ฮณ, the Eulerโ€“Mascheroni constant, sometimes called simply Euler's constant), or as Napier's constant. However, Euler's choice of the symbol e is said to have been retained in his honor. The constant was discovered by the Swiss mathematician Jacob Bernoulli while studying compound interest.

The number e has eminent importance in mathematics, alongside 0, 1, ฯ€, and i. All five of these numbers play important and recurring roles across mathematics, and these five constants appear in one formulation of Euler's identity. Like the constant ฯ€, e is also irrational (i.e. it cannot be represented as ratio of integers) and transcendental (i.e. it is not a root of any non-zero polynomial with rational coefficients). The numerical value of e truncated to 50 decimal places is

Discussed on

๐Ÿ”— The deadliest school massacre in US history occurred in 1927

๐Ÿ”— Crime ๐Ÿ”— Terrorism ๐Ÿ”— Schools ๐Ÿ”— Michigan

The Bath School disaster, also known as the Bath School massacre, was a series of violent attacks perpetrated by Andrew Kehoe on Mayย 18, 1927, in Bath Township, Michigan. The attacks killed 38ย elementary schoolchildren and 6ย adults, and injured at least 58ย other people. Prior to his timed explosives going off at the Bath Consolidated School building, Kehoe had murdered his wife, Nellie Price Kehoe, and firebombed his farm. Arriving at the site of the school explosion, Kehoe died when he detonated explosives concealed in his truck.

Kehoe, the 55-year-old school board treasurer, was angered by increased taxes and his defeat in the April 5, 1926, election for township clerk. He was thought by locals to have planned his "murderous revenge" after that public defeat. Kehoe had a reputation for difficulty on the school board and in personal dealings. In addition, he was notified that his mortgage was going to be foreclosed upon in June 1926. For much of the next year until May 1927, Kehoe purchased explosives. He secretly hid them on his property and under the school.

On May 18, 1927, Kehoe then set off almost simultaneous explosions at his farmstead and at the Bath Consolidated School. His explosives destroyed the farm's buildings and ripped through the north wing of the Bath Consolidated School building. As rescuers began working at the school, Kehoe drove up to the schoolyard and detonated dynamite inside his shrapnel-filled truck. The truck explosion killed Kehoe and several others nearby. Bystanders were injured. During the rescue and recovery efforts, searchers discovered an additional 500ย pounds (230ย kg) of unexploded dynamite and pyrotol in the south wing of the school that was set to explode at the same time as the initial explosions in the north wing; Kehoe had apparently intended to destroy the entire school and kill everyone in it.

Discussed on

๐Ÿ”— Intellipedia (U.S. intelligence agencies' internal wiki)

๐Ÿ”— United States/U.S. Government ๐Ÿ”— United States

Intellipedia is an online system for collaborative data sharing used by the United States Intelligence Community (IC). It was established as a pilot project in late 2005 and formally announced in April 2006. Intellipedia consists of three wikis running on the separate JWICS (Intellipedia-TS), SIPRNet (Intellipedia-S), and DNI-U (Intellipedia-U) networks. The levels of classification allowed for information on the three wikis are Top Secret Sensitive Compartmented Information (TS SCI), Secret (S), and Sensitive But Unclassified (SBU or FOUO) information, respectively. Each of the wikis is used by individuals with appropriate clearances from the 16 agencies of the US intelligence community and other national-security related organizations, including Combatant Commands and other federal departments. The wikis are not open to the public.

Intellipedia is a project of the Office of the Director of National Intelligence (ODNI) Intelligence Community Enterprise Services (ICES) office headquartered in Fort Meade, Maryland. It includes information on the regions, people, and issues of interest to the communities using its host networks. Intellipedia uses MediaWiki, the same software used by the Wikipedia free-content encyclopedia project. To the contrary of mainstream Wikipedia, its intelligence analogue encourages editing that incorporates personal points of view regardless of rank as it was decided that, "much of the self-corrective knowledge in the Intelligence Community resides in personal points of view," and that, "not all good ideas originate at the top."

The Secret version connected to SIPRNet predominantly serves Department of Defense and the Department of State personnel, many of whom do not use the Top Secret JWICS network on a day-to-day basis. Users on unclassified networks can access Intellipedia from remote terminals outside their workspaces via a VPN, in addition to their normal workstations. Open Source Intelligence (OSINT) users share information on the unclassified Intelink-U wiki.

๐Ÿ”— Shakespeare (programming language)

๐Ÿ”— Shakespeare

The Shakespeare Programming Language (SPL) is an esoteric programming language designed by Jon ร…slund and Karl Hasselstrรถm. Like the Chef programming language, it is designed to make programs appear to be something other than programs; in this case, Shakespearean plays.

A character list in the beginning of the program declares a number of stacks, naturally with names like "Romeo" and "Juliet". These characters enter into dialogue with each other in which they manipulate each other's topmost values, push and pop each other, and do I/O. The characters can also ask each other questions which behave as conditional statements. On the whole, the programming model is very similar to assembly language but much more verbose.

Discussed on

๐Ÿ”— CipherSaber - A 'political' encryption cipher

๐Ÿ”— Computing ๐Ÿ”— Cryptography ๐Ÿ”— Cryptography/Computer science

CipherSaber is a simple symmetric encryption protocol based on the RC4 stream cipher. Its goals are both technical and political: it gives reasonably strong protection of message confidentiality, yet it's designed to be simple enough that even novice programmers can memorize the algorithm and implement it from scratch. According to the designer, a CipherSaber version in the QBASIC programming language takes just sixteen lines of code. Its political aspect is that because it's so simple, it can be reimplemented anywhere at any time, and so it provides a way for users to communicate privately even if government or other controls make distribution of normal cryptographic software completely impossible.

Discussed on

๐Ÿ”— Nomic

๐Ÿ”— Games

Nomic is a game created in 1982 by philosopher Peter Suber in which the rules of the game include mechanisms for the players to change those rules, usually beginning through a system of democratic voting.

Nomic is a game in which changing the rules is a move. In that respect it differs from almost every other game. The primary activity of Nomic is proposing changes in the rules, debating the wisdom of changing them in that way, voting on the changes, deciding what can and cannot be done afterwards, and doing it. Even this core of the game, of course, can be changed.

The initial ruleset was designed by Peter Suber, and first published in Douglas Hofstadter's column Metamagical Themas in Scientific American in June 1982. The column discussed Suber's then-upcoming book, The Paradox of Self-Amendment, which was published some years later. Nomic now refers to many games, all based on the initial ruleset.

The game is in some ways modeled on modern government systems. It demonstrates that in any system where rule changes are possible, a situation may arise in which the resulting laws are contradictory or insufficient to determine what is in fact legal. Because the game models (and exposes conceptual questions about) a legal system and the problems of legal interpretation, it is named after ฮฝฯŒฮผฮฟฯ‚ (nomos), Greek for "law".

While the victory condition in Suber's initial ruleset is the accumulation of 100 points by the roll of dice, he once said that "this rule is deliberately boring so that players will quickly amend it to please themselves". Players can change the rules to such a degree that points can become irrelevant in favor of a true currency, or make victory an unimportant concern. Any rule in the game, including the rules specifying the criteria for winning and even the rule that rules must be obeyed, can be changed. Any loophole in the ruleset, however, may allow the first player to discover it the chance to pull a "scam" and modify the rules to win the game. Complicating this process is the fact that Suber's initial ruleset allows for the appointment of judges to preside over issues of rule interpretation.

Discussed on

๐Ÿ”— Valid Email Addresses

๐Ÿ”— Technology ๐Ÿ”— Internet ๐Ÿ”— Computing ๐Ÿ”— Computing/Networking

An email address identifies an email box to which email messages are delivered. A wide variety of formats were used in early email systems, but only a single format is used today, following the specifications developed for Internet mail systems since the 1980s. This article uses the term email address to refer to the addr-spec defined in RFC 5322, not to the address that is commonly used; the difference is that an address may contain a display name, a comment, or both.

An email address such as John.Smith@example.com is made up of a local-part, an @ symbol, then a case-insensitive domain. Although the standard requires the local part to be case-sensitive, it also urges that receiving hosts deliver messages in a case-independent fashion, e.g., that the mail system at example.com treat John.Smith as equivalent to john.smith; some mail systems even treat them as equivalent to johnsmith. Mail systems often limit their users' choice of name to a subset of the technically valid characters, and in some cases also limit which addresses it is possible to send mail to.

With the introduction of internationalized domain names, efforts are progressing to permit non-ASCII characters in email addresses.

Discussed on

๐Ÿ”— Wife Acceptance Factor

๐Ÿ”— Psychology ๐Ÿ”— Gender Studies

Wife acceptance factor, wife approval factor, or wife appeal factor (WAF) is an assessment of design elements that either increase or diminish the likelihood a wife will approve the purchase of expensive consumer electronics products such as high-fidelity loudspeakers, home theater systems and personal computers. Stylish, compact forms and appealing colors are commonly considered to have a high WAF. The term is a tongue-in-cheek play on electronics jargon such as "form factor" and "power factor" and derives from the idea that men are predisposed to appreciate gadgetry and performance criteria whereas women must be wooed by visual and aesthetic factors.

Discussed on

๐Ÿ”— Ford Nucleon - a nuclear-powered concept car from 1958

๐Ÿ”— Automobiles

The Ford Nucleon is a concept car developed by Ford in 1957 designed as a future nuclear-powered car, one of a handful of such designs during the 1950s and '60s. The concept was only demonstrated as a scale model. The design did not include an internal-combustion engine; rather, the vehicle was to be powered by a small nuclear reactor in the rear of the vehicle, based on the assumption that this would one day be possible by reducing sizes. The car was to use a steam engine powered by uranium fission similar to those found in nuclear submarines.

The mock-up of the car can be viewed at the Henry Ford Museum in Dearborn, Michigan.

Discussed on

๐Ÿ”— Degrowth

๐Ÿ”— Economics ๐Ÿ”— Basic Income

Degrowth (French: dรฉcroissance) is a political, economic, and social movement based on ecological economics, anti-consumerist and anti-capitalist ideas. It is also considered an essential economic strategy responding to the limits-to-growth dilemma (see The Path to Degrowth in Overdeveloped Countries and post-growth). Degrowth thinkers and activists advocate for the downscaling of production and consumption โ€“ the contraction of economies โ€“ arguing that overconsumption lies at the root of long term environmental issues and social inequalities. Key to the concept of degrowth is that reducing consumption does not require individual martyring or a decrease in well-being. Rather, "degrowthers" aim to maximize happiness and well-being through non-consumptive meansโ€”sharing work, consuming less, while devoting more time to art, music, family, nature, culture and community.

Discussed on