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🔗 Mathematics

Pattern theory, formulated by Ulf Grenander, is a mathematical formalism to describe knowledge of the world as patterns. It differs from other approaches to artificial intelligence in that it does not begin by prescribing algorithms and machinery to recognize and classify patterns; rather, it prescribes a vocabulary to articulate and recast the pattern concepts in precise language. Broad in its mathematical coverage, Pattern Theory spans algebra and statistics, as well as local topological and global entropic properties.

In addition to the new algebraic vocabulary, its statistical approach is novel in its aim to:

• Identify the hidden variables of a data set using real world data rather than artificial stimuli, which was previously commonplace.
• Formulate prior distributions for hidden variables and models for the observed variables that form the vertices of a Gibbs-like graph.
• Study the randomness and variability of these graphs.
• Create the basic classes of stochastic models applied by listing the deformations of the patterns.
• Synthesize (sample) from the models, not just analyze signals with them.

The Brown University Pattern Theory Group was formed in 1972 by Ulf Grenander. Many mathematicians are currently working in this group, noteworthy among them being the Fields Medalist David Mumford. Mumford regards Grenander as his "guru" in Pattern Theory.

🔗 Help 🔗 Reliability

This is a non-exhaustive list of sources whose reliability and use on Wikipedia are frequently discussed. This list summarizes prior consensus and consolidates links to the most in-depth and recent discussions from the reliable sources noticeboard and elsewhere on Wikipedia.

Click here to check the list of sources.

Context matters tremendously, and some sources may or may not be suitable for certain uses depending on the situation. When in doubt, defer to the linked discussions for more detailed information on a particular source and its use. Consensus can change, and if more recent discussions considering new evidence or arguments reach a different consensus, this list should be updated to reflect those changes.

Reliability is an inquiry that takes place pursuant to the verifiability policy and the reliable sources guideline. Note that verifiability is only one of Wikipedia's core content policies, which also include neutral point of view and no original research. These policies work together to determine whether information from reliable sources should be included or excluded.

🔗 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.

🔗 United States 🔗 Mathematics

Garfield's proof of the Pythagorean theorem is an original proof of the Pythagorean theorem discovered by James A. Garfield (November 19, 1831 – September 19, 1881), the 20th president of the United States. The proof appeared in print in the New-England Journal of Education (Vol. 3, No.14, April 1, 1876). At the time of the publication of the proof Garfield was a congressman from Ohio. He assumed the office of President on March 4, 1881, and served in that position until his death on September 19, 1881, having succumbed to injuries sustained when he was shot in an assassination in July. Garfield is thus far the only President of the United States to have contributed anything original to mathematics. The proof is nontrivial and, according to the historian of mathematics William Dunham, "Garfield's is really a very clever proof." The proof appears as the 231st proof in The Pythagorean Proposition, a compendium of 370 different proofs of the Pythagorean theorem.

🔗 Cryptography 🔗 Cryptography/Computer science 🔗 Citizendium Porting

Kerckhoffs's principle (also called Kerckhoffs's desideratum, assumption, axiom, doctrine or law) of cryptography was stated by Netherlands born cryptographer Auguste Kerckhoffs in the 19th century: A cryptosystem should be secure even if everything about the system, except the key, is public knowledge.

Kerckhoffs's principle was reformulated (or possibly independently formulated) by American mathematician Claude Shannon as "the enemy knows the system", i.e., "one ought to design systems under the assumption that the enemy will immediately gain full familiarity with them". In that form, it is called Shannon's maxim. This concept is widely embraced by cryptographers, in contrast to "security through obscurity", which is not.

🔗 Languages 🔗 Argentina 🔗 Wales

Patagonian Welsh (Welsh: Cymraeg y Wladfa) is a variety of the Welsh language spoken in the Patagonia region's Y Wladfa, Welsh settlements located in Chubut Province, Argentina. Though Patagonian Welsh is distinct from the several dialects used in Wales itself, the dialects have a high degree of mutual intelligibility, and speakers from Wales and Patagonia are able to communicate readily. Numerous toponyms throughout the Chubut Valley are of Welsh origin.

Teachers are sent from Wales to teach the language and to train local tutors in the Welsh language. There is some prestige in knowing the language, even among those not of Welsh descent. Welsh education and projects are mainly funded by the Welsh Government, British Council, Cardiff University and the Welsh–Argentine Association. In 2005, there were 62 Welsh classes in the area and Welsh was taught as a subject in two primary schools and two colleges in the region of Gaiman. There is also a bilingual Welsh–Spanish language school called Ysgol yr Hendre situated in Trelew, and a college located in Esquel. In 2016, there were three bilingual Welsh–Spanish primary schools in Patagonia.

In 2024–25, the number of registered learners—encompassing students in schools and adult programs—reached 1106, a significant increase from 623 in 2020.

The formal Eisteddfod poetry competitions have been revived, and are now bilingual in Welsh and Spanish.

🔗 Disability 🔗 Deaf

Tadoma is a method of communication used by deafblind individuals, in which the deafblind person places their little finger on the speaker's lips and their fingers along the jawline. The middle three fingers often fall along the speaker's cheeks with the little finger picking up the vibrations of the speaker's throat. It is sometimes referred to as tactile lipreading, as the deafblind person feels the movement of the lips, as well as vibrations of the vocal cords, puffing of the cheeks and the warm air produced by nasal sounds such as 'N' and 'M'. There are variations in the hand positioning, and it is a method sometimes used by people to support their remaining hearing.

In some cases, especially if the speaker knows sign language, the deaf-blind person may use the Tadoma method with one hand, to feel the speaker's face, and, at the same time, the deaf-blind person may use their other hand to feel the speaker sign the same words. In this way, the two methods reinforce each other, giving the deaf-blind person a better chance of understanding what the speaker is trying to communicate.

In addition, the Tadoma method can provide the deaf-blind person with a closer connection with speech than they might otherwise have had. This can, in turn, help them to retain speech skills that they developed before going deaf, and in special cases, to learn how to speak brand new words.

It is a difficult method to learn and use, and is rarely used nowadays. However, a small number of deafblind people successfully use Tadoma in everyday communication.

🔗 Computing 🔗 Computer science 🔗 Computing/Software

This is a list of notable lexer generators and parser generators for various language classes.

🔗 Technology 🔗 Spaceflight 🔗 Solar System/Mars 🔗 Solar System

Terraforming of Mars is a procedure that would comprise of planetary engineering project or concurrent projects, with the goal of transforming the planet from one hostile to terrestrial life to one that can sustainably host humans and other lifeforms free of protection or mediation. The process would presumably involve the rehabilitation of the planet's extant climate, atmosphere, and surface through a variety of resource-intensive initiatives, and the installation of a novel ecological system or systems.

Justifications for choosing Mars over other potential terraforming targets include the presence of water and a geological history that suggests it once harbored a dense atmosphere similar to Earth’s. Hazards and difficulties include low gravity, low light levels relative to Earth’s, and the lack of a magnetic field.

Objections to the project include questions about its feasibility, general ethical concerns about terraforming, and the considerable cost that such an undertaking would involve. Reasons for terraforming the planet include allaying concerns about resource use and depletion on Earth and arguments that the altering and subsequent or concurrent settlement of other planets decreases the odds of humanity's extinction.

Disagreement exists about whether current technology could render the planet habitable.

🔗 United States 🔗 Finance & Investment

The Onion Futures Act is a United States law banning the trading of futures contracts on onions as well as "motion picture box office receipts".

In 1955, two onion traders, Sam Siegel and Vincent Kosuga, cornered the onion futures market on the Chicago Mercantile Exchange. The resulting regulatory actions led to the passing of the act on August 28, 1958. As of January 2020, it remains in effect.