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🔗 Computing

In markup languages and the digital humanities, overlap occurs when a document has two or more structures that interact in a non-hierarchical manner. A document with overlapping markup cannot be represented as a tree. This is also known as concurrent markup. Overlap happens, for instance, in poetry, where there may be a metrical structure of feet and lines; a linguistic structure of sentences and quotations; and a physical structure of volumes and pages and editorial annotations.

🔗 Computer science 🔗 Statistics

A Boltzmann machine (also called stochastic Hopfield network with hidden units) is a type of stochastic recurrent neural network. It is a Markov random field. It was translated from statistical physics for use in cognitive science. The Boltzmann machine is based on stochastic spin-glass model with an external field, i.e., a Sherrington–Kirkpatrick model that is a stochastic Ising Model and applied to machine learning.

Boltzmann machines can be seen as the stochastic, generative counterpart of Hopfield networks. They were one of the first neural networks capable of learning internal representations, and are able to represent and (given sufficient time) solve combinatoric problems.

They are theoretically intriguing because of the locality and Hebbian nature of their training algorithm (being trained by Hebb's rule), and because of their parallelism and the resemblance of their dynamics to simple physical processes. Boltzmann machines with unconstrained connectivity have not proven useful for practical problems in machine learning or inference, but if the connectivity is properly constrained, the learning can be made efficient enough to be useful for practical problems.

They are named after the Boltzmann distribution in statistical mechanics, which is used in their sampling function. That's why they are called "energy based models" (EBM). They were invented in 1985 by Geoffrey Hinton, then a Professor at Carnegie Mellon University, and Terry Sejnowski, then a Professor at Johns Hopkins University.

🔗 Biography 🔗 Writing systems 🔗 Indigenous peoples of North America 🔗 Oklahoma

Sequoyah (ᏍᏏᏉᏯ Ssiquoya, as he signed his name, or ᏎᏉᏯ Se-quo-ya, as is often spelled in Cherokee; named in English George Gist or George Guess) (c.1770–1843), was a Native American polymath of the Cherokee Nation. In 1821 he completed his independent creation of a Cherokee syllabary, making reading and writing in Cherokee possible. This was one of the very few times in recorded history that a member of a pre-literate people created an original, effective writing system (another example being Shong Lue Yang). After seeing its worth, the people of the Cherokee Nation rapidly began to use his syllabary and officially adopted it in 1825. Their literacy rate quickly surpassed that of surrounding European-American settlers.

🔗 Biography 🔗 Computing 🔗 London 🔗 Philosophy 🔗 Philosophy/Logic 🔗 Business 🔗 England 🔗 Biography/science and academia 🔗 Philosophy/Philosophers 🔗 Philately 🔗 Biography/Core biographies

Charles Babbage (; 26 December 1791 – 18 October 1871) was an English polymath. A mathematician, philosopher, inventor and mechanical engineer, Babbage originated the concept of a digital programmable computer.

Considered by some to be a father of the computer, Babbage is credited with inventing the first mechanical computer that eventually led to more complex electronic designs, though all the essential ideas of modern computers are to be found in Babbage's Analytical Engine. His varied work in other fields has led him to be described as "pre-eminent" among the many polymaths of his century.

Parts of Babbage's incomplete mechanisms are on display in the Science Museum in London. In 1991, a functioning difference engine was constructed from Babbage's original plans. Built to tolerances achievable in the 19th century, the success of the finished engine indicated that Babbage's machine would have worked.

🔗 Mathematics

Hilbert's paradox of the Grand Hotel (colloquial: Infinite Hotel Paradox or Hilbert's Hotel) is a thought experiment which illustrates a counterintuitive property of infinite sets. It is demonstrated that a fully occupied hotel with infinitely many rooms may still accommodate additional guests, even infinitely many of them, and this process may be repeated infinitely often. The idea was introduced by David Hilbert in a 1924 lecture "Über das Unendliche", reprinted in (Hilbert 2013, p.730), and was popularized through George Gamow's 1947 book One Two Three... Infinity.

🔗 United States/U.S. Government 🔗 United States 🔗 Mass surveillance 🔗 Espionage 🔗 Computing 🔗 Australia 🔗 New Zealand 🔗 United Kingdom 🔗 Computing/Computer Security 🔗 Computing/Networking

XKeyscore (XKEYSCORE or XKS) is a secret computer system used by the United States National Security Agency (NSA) for searching and analyzing global Internet data, which it collects in real time. The NSA has shared XKeyscore with other intelligence agencies, including the Australian Signals Directorate, Canada's Communications Security Establishment, New Zealand's Government Communications Security Bureau, Britain's Government Communications Headquarters, Japan's Defense Intelligence Headquarters, and Germany's Bundesnachrichtendienst.

In July 2013, Edward Snowden publicly revealed the program's purpose and use by the NSA in The Sydney Morning Herald and O Globo newspapers. The code name was already public knowledge because it was mentioned in earlier articles, and, like many other code names, it appears in job postings and online résumés of employees.

On July 3, 2014, German public broadcaster Norddeutscher Rundfunk, a member of ARD, published excerpts of XKeyscore's source code. A team of experts analyzed the source code.

🔗 United States 🔗 Biography 🔗 United States/Ohio 🔗 Backpacking

Emma Rowena (Caldwell) Gatewood, known as Grandma Gatewood, (October 25, 1887 – June 4, 1973), was an American ultra-light hiking pioneer. After a difficult life as a farm wife, mother of eleven children, and survivor of domestic violence, she became famous as the first solo female thru-hiker of the 2,168-mile (3,489 km) Appalachian Trail (A.T.) in 1955 at the age of 67. She subsequently became the first person (male or female) to hike the A.T. three times, after completing a second thru-hike two years later, followed by a section-hike in 1964. In the meantime, she hiked 2,000 miles (3,200 km) of the Oregon Trail in 1959. In her later years, she continued to travel and hike, and worked on a section of what would become the Buckeye Trail. The media coverage surrounding her feats was credited for generating interest in maintaining the A.T. and in hiking generally. Among many other honors, she was posthumously inducted into the Appalachian Trail Hall of Fame in 2012.

🔗 Russia 🔗 Mathematics 🔗 Russia/science and education in Russia 🔗 Switzerland 🔗 Anthroponymy

In mathematics and physics, many topics are named in honor of Swiss mathematician Leonhard Euler (1707–1783), who made many important discoveries and innovations. Many of these items named after Euler include their own unique function, equation, formula, identity, number (single or sequence), or other mathematical entity. Many of these entities have been given simple and ambiguous names such as Euler's function, Euler's equation, and Euler's formula.

Euler's work touched upon so many fields that he is often the earliest written reference on a given matter. In an effort to avoid naming everything after Euler, some discoveries and theorems are attributed to the first person to have proved them after Euler.

🔗 United States 🔗 Law 🔗 Politics 🔗 National Archives 🔗 Politics/American politics

The Alien and Sedition Acts were a set of four laws enacted in 1798 that applied restrictions to immigration and speech in the United States. The Naturalization Act increased the requirements to seek citizenship, the Alien Friends Act allowed the president to imprison and deport non-citizens, the Alien Enemies Act gave the president additional powers to detain non-citizens during times of war, and the Sedition Act criminalized false and malicious statements about the federal government. The Alien Friends Act and the Sedition Act expired after a set number of years, and the Naturalization Act was repealed in 1802. The Alien Enemies Act is still in effect.

The Alien and Sedition Acts were controversial. They were supported by the Federalist Party, and supporters argued that the bills strengthened national security during the Quasi-War, an undeclared naval war with France from 1798 to 1800. The acts were denounced by Democratic-Republicans as suppression of voters and violation of free speech under the First Amendment. While they were in effect, the Alien and Sedition Acts, and the Sedition Act in particular, were used to suppress publishers affiliated with the Democratic-Republicans, and several publishers were arrested for criticism of the Adams administration. The Democratic-Republicans took power in 1800, in part because of backlash to the Alien and Sedition Acts, and all but the Alien Enemies Act were eliminated by the next Congress. The Alien Enemies Act has been invoked several times since, particularly during World War II. The Alien and Sedition Acts are generally received negatively by modern historians, and the Supreme Court has since indicated that aspects of the laws would be found unconstitutional if challenged.

🔗 Geology 🔗 Michigan 🔗 Gemology and Jewelry/Gemstones 🔗 Gemology and Jewelry

A Petoskey stone is a rock and a fossil, often pebble-shaped, that is composed of a fossilized rugose coral, Hexagonaria percarinata. Such stones were formed as a result of glaciation, in which sheets of ice plucked stones from the bedrock, grinding off their rough edges and depositing them in the northwestern (and some in the northeastern) portion of Michigan's lower peninsula. In those same areas of Michigan, complete fossilized coral colony heads can be found in the source rocks for the Petoskey stones.

Petoskey stones are found in the Gravel Point Formation of the Traverse Group. They are fragments of a coral reef that was originally deposited during the Devonian period. When dry, the stone resembles ordinary limestone but when wet or polished using lapidary techniques, the distinctive mottled pattern of the six-sided coral fossils emerges. It is sometimes made into decorative objects. Other forms of fossilized coral are also found in the same location.

In 1965, it was named the state stone of Michigan.