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🔗 Databases 🔗 Databases/Computer science

Codd's twelve rules are a set of thirteen rules (numbered zero to twelve) proposed by Edgar F. Codd, a pioneer of the relational model for databases, designed to define what is required from a database management system in order for it to be considered relational, i.e., a relational database management system (RDBMS). They are sometimes jokingly referred to as "Codd's Twelve Commandments".

🔗 Mathematics

In number theory, the Pólya conjecture stated that "most" (i.e., 50% or more) of the natural numbers less than any given number have an odd number of prime factors. The conjecture was posited by the Hungarian mathematician George Pólya in 1919, and proved false in 1958 by C. Brian Haselgrove.

The size of the smallest counterexample is often used to show how a conjecture can be true for many cases, and still be false, providing an illustration for the strong law of small numbers.

🔗 Astronomy 🔗 Geology 🔗 Geology/Meteorites 🔗 Solar System

The Perseids are a prolific meteor shower associated with the comet Swift–Tuttle. The meteors are called the Perseids because the point from which they appear to hail (called the radiant) lies in the constellation Perseus.

🔗 Philately 🔗 Czech Republic

The Prague pneumatic post (Czech: Pražská potrubní pošta) is the world's last preserved municipal pneumatic post system. It is an underground system of metal tubes under the wider centre of Prague, totaling about 55 kilometres (34 mi) in length. The system started service in 1889 and remained in use by the government, banks and the media until it was rendered inoperative by the August 2002 European floods.

Sold on by former owner Telefónica O2 Czech Republic after some limited attempts to make repairs, the system now belongs to businessman Zdeněk Dražil, who has announced plans to repair and reopen it as a working tourist attraction. As of 2012, however, it remains closed.

🔗 Finance & Investment 🔗 Economics 🔗 Sociology 🔗 Sociology/social movements 🔗 Basic Income 🔗 Social Work 🔗 International development

Basic income, also called universal basic income (UBI), citizen's income, citizen's basic income in the United Kingdom, basic income guarantee in the United States and Canada, or basic living stipend or guaranteed annual income or universal demogrant, is a governmental public program for a periodic payment delivered to all on an individual basis without means test or work requirement. The incomes would be:

• Unconditional: A basic income would vary with age, but with no other conditions. Everyone of the same age would receive the same basic income, whatever their gender, employment status, family structure, contribution to society, housing costs, or anything else.
• Automatic: Someone's basic income would be automatically paid weekly or monthly into a bank account or similar.
• Non-withdrawable: Basic incomes would not be means-tested. Whether someone's earnings increase, decrease, or stay the same, their basic income will not change.
• Individual: Basic incomes would be paid on an individual basis and not on the basis of a couple or household.
• As a right: Every legal resident would receive a basic income, subject to a minimum period of legal residency and continuing residency for most of the year.

Basic income can be implemented nationally, regionally or locally. An unconditional income that is sufficient to meet a person's basic needs (at or above the poverty line) is sometimes called a full basic income while if it is less than that amount, it is sometimes called partial. A welfare system with some characteristics similar to those of a basic income is a negative income tax in which the government stipend is gradually reduced with higher labour income. Some welfare systems are sometimes regarded as steps on the way to a basic income, but because they have conditionalities attached they are not basic incomes. If they raise household incomes to specified minima they are called guaranteed minimum income systems. For example, Bolsa Família in Brazil is restricted to poor families and the children are obligated to attend school.

Several political discussions are related to the basic income debate. Examples include the debates regarding robotization, artificial intelligence (AI), and the future of work. A key issue in these debates is whether robotisation and AI will significantly reduce the number of available jobs. Basic income often comes up as a proposal in these discussions.

PechaKucha (Japanese: ぺちゃくちゃ, IPA: [petɕa kɯ̥tɕa], chit-chat) is a storytelling format where a presenter shows 20 slides for 20 seconds of commentary each (6 minutes and 40 seconds total). At a PechaKucha Night, individuals gather at a venue to share personal presentations about their work. The PechaKucha format can be used, for example, in business presentations to clients or staff, as well as in education settings.

Inspired by their desire to "talk less, show more," Astrid Klein and Mark Dytham of Tokyo's Klein-Dytham Architecture (KDa) created PechaKucha in February 2003. It was a way to attract people to SuperDeluxe, their experimental event space in Roppongi, and to enable young designers to meet, show their work, and exchange ideas in 6 minutes 40 seconds.

In 2004, cities in Europe began hosting PK Nights and days, followed over the years by hundreds of others. As of April 2019, PKNs had been held in more than 1,142 cities worldwide. More than 3 million people have attended a PK Night.

PechaKucha is a registered trademark of PechaKucha, Inc.

In January 2018, PK's Astrid Klein, Mark Dytham, and Sean Smyth established PK, Inc. to create software to expand the PK platform.

🔗 Physics

The Large Electron–Positron Collider (LEP) was one of the largest particle accelerators ever constructed.

It was built at CERN, a multi-national centre for research in nuclear and particle physics near Geneva, Switzerland. LEP collided electrons with positrons at energies that reached 209 GeV. It was a circular collider with a circumference of 27 kilometres built in a tunnel roughly 100 m (300 ft) underground and passing through Switzerland and France. LEP was used from 1989 until 2000. Around 2001 it was dismantled to make way for the Large Hadron Collider, which re-used the LEP tunnel. To date, LEP is the most powerful accelerator of leptons ever built.

🔗 Game theory

Game theory studies strategic interaction between individuals in situations called games. Classes of these games have been given names. This is a list of the most commonly studied games

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🔗 Games

Quantum tic-tac-toe is a "quantum generalization" of tic-tac-toe in which the players' moves are "superpositions" of plays in the classical game. The game was invented by Allan Goff of Novatia Labs, who describes it as "a way of introducing quantum physics without mathematics", and offering "a conceptual foundation for understanding the meaning of quantum mechanics".