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🔗 Cryptography 🔗 Cryptography/Computer science

In cryptography, a zero-knowledge proof or zero-knowledge protocol is a method by which one party (the prover) can prove to another party (the verifier) that they know a value x, without conveying any information apart from the fact that they know the value x. The essence of zero-knowledge proofs is that it is trivial to prove that one possesses knowledge of certain information by simply revealing it; the challenge is to prove such possession without revealing the information itself or any additional information.

If proving a statement requires that the prover possesses some secret information, then the verifier will not be able to prove the statement to anyone else without possessing the secret information. The statement being proved must include the assertion that the prover has such knowledge, but not the knowledge itself. Otherwise, the statement would not be proved in zero-knowledge because it provides the verifier with additional information about the statement by the end of the protocol. A zero-knowledge proof of knowledge is a special case when the statement consists only of the fact that the prover possesses the secret information.

Interactive zero-knowledge proofs require interaction between the individual (or computer system) proving their knowledge and the individual validating the proof.

A protocol implementing zero-knowledge proofs of knowledge must necessarily require interactive input from the verifier. This interactive input is usually in the form of one or more challenges such that the responses from the prover will convince the verifier if and only if the statement is true, i.e., if the prover does possess the claimed knowledge. If this were not the case, the verifier could record the execution of the protocol and replay it to convince someone else that they possess the secret information. The new party's acceptance is either justified since the replayer does possess the information (which implies that the protocol leaked information, and thus, is not proved in zero-knowledge), or the acceptance is spurious, i.e., was accepted from someone who does not actually possess the information.

Some forms of non-interactive zero-knowledge proofs exist, but the validity of the proof relies on computational assumptions (typically the assumptions of an ideal cryptographic hash function).

🔗 Psychology

Boredom boreout syndrome is a psychological disorder that causes physical illness, mainly caused by mental underload at the workplace due to lack of either adequate quantitative or qualitative workload. One reason for bore-out could be that the initial job description does not match the actual work.

This theory was first expounded in 2007 in Diagnose Boreout, a book by Peter Werder and Philippe Rothlin, two Swiss business consultants.

🔗 Computer science 🔗 Mathematics 🔗 Systems

An L-system or Lindenmayer system is a parallel rewriting system and a type of formal grammar. An L-system consists of an alphabet of symbols that can be used to make strings, a collection of production rules that expand each symbol into some larger string of symbols, an initial "axiom" string from which to begin construction, and a mechanism for translating the generated strings into geometric structures. L-systems were introduced and developed in 1968 by Aristid Lindenmayer, a Hungarian theoretical biologist and botanist at the University of Utrecht. Lindenmayer used L-systems to describe the behaviour of plant cells and to model the growth processes of plant development. L-systems have also been used to model the morphology of a variety of organisms and can be used to generate self-similar fractals.

🔗 Physics 🔗 Lists 🔗 Statistics 🔗 Astronomy 🔗 Time 🔗 Futures studies 🔗 Geology 🔗 Extinction 🔗 Solar System 🔗 Astronomy/Solar System

While the future can never be predicted with absolute certainty, present understanding in various scientific fields allows for the prediction of some far-future events, if only in the broadest outline. These fields include astrophysics, which has revealed how planets and stars form, interact, and die; particle physics, which has revealed how matter behaves at the smallest scales; evolutionary biology, which predicts how life will evolve over time; and plate tectonics, which shows how continents shift over millennia.

All projections of the future of Earth, the Solar System, and the universe must account for the second law of thermodynamics, which states that entropy, or a loss of the energy available to do work, must rise over time. Stars will eventually exhaust their supply of hydrogen fuel and burn out. Close encounters between astronomical objects gravitationally fling planets from their star systems, and star systems from galaxies.

Physicists expect that matter itself will eventually come under the influence of radioactive decay, as even the most stable materials break apart into subatomic particles. Current data suggest that the universe has a flat geometry (or very close to flat), and thus will not collapse in on itself after a finite time, and the infinite future allows for the occurrence of a number of massively improbable events, such as the formation of Boltzmann brains.

The timelines displayed here cover events from the beginning of the 11th millennium to the furthest reaches of future time. A number of alternative future events are listed to account for questions still unresolved, such as whether humans will become extinct, whether protons decay, and whether the Earth survives when the Sun expands to become a red giant.

🔗 United States 🔗 Video games 🔗 Computing 🔗 Film 🔗 Military history 🔗 Military history/North American military history 🔗 Military history/United States military history 🔗 Film/American cinema 🔗 United States/Film - American cinema 🔗 Science Fiction 🔗 Computer Security 🔗 Computer Security/Computing 🔗 Military history/Cold War 🔗 Cold War 🔗 United States/Washington - Seattle 🔗 United States/Washington 🔗 Film/War films 🔗 Military history/War films

WarGames is a 1983 American science fiction techno-thriller film written by Lawrence Lasker and Walter F. Parkes and directed by John Badham. The film, which stars Matthew Broderick, Dabney Coleman, John Wood, and Ally Sheedy, follows David Lightman (Broderick), a young hacker who unwittingly accesses a United States military supercomputer programmed to simulate, predict and execute nuclear war against the Soviet Union.

WarGames was a critical and commercial success, grossing $125 million worldwide against a $12 million budget. The film was nominated for three Academy Awards.

🔗 Visual arts 🔗 Morocco

Zellige (Arabic: [zˈliʑ]; Arabic: الزليج‎; also zelige or zellij or zileej) is mosaic tilework made from individually chiseled geometric tiles set into a plaster base. This form of Islamic art is one of the main characteristics of Moroccan architecture. It consists of geometrically patterned mosaics, used to ornament walls, ceilings, fountains, floors, pools and tables. The Moroccan traditional patterns and styles are found inside famous buildings such as Al-Qarawiyyin Mosque in Fez, the Alhambra in Granada, Spain, the Great Mosque of Cordoba, the Ben Youssef Madrasa in Marrakech, and the Hassan II mosque in Casablanca, which adds a new color palette with traditional designs.

🔗 Books 🔗 Psychology 🔗 Japan

The Mariko Aoki phenomenon (青木まりこ現象, Aoki Mariko genshō) is a Japanese expression referring to an urge to defecate that is suddenly felt after entering bookstores. The phenomenon's name derives from the name of the woman who mentioned the phenomenon in a magazine article in 1985. According to Japanese social psychologist Shozo Shibuya, the specific causes that trigger a defecation urge in bookstores are not yet clearly understood (as of 2014). There are also some who are skeptical about whether such a peculiar phenomenon really exists at all, and it is sometimes discussed as one type of urban myth.

The series of processes through which being in a bookstore leads to an awareness of a defecation urge is something that cannot be explained from a medical perspective as a single pathological concept, at least at present. According to a number of discussions on the topic, even if it can be sufficiently found that this phenomenon actually exists, it is a concept that would be difficult to be deemed a specific pathological entity (such as a "Mariko Aoki disease", for example). On the other hand, it is also a fact that a considerable number of the intellectuals (particularly clinicians) who discuss this phenomenon have adopted existing medical terminology such as from diagnostics and pathology. Borrowing from this approach, this article also uses expressions from existing medical terminology for convenience.

🔗 Computing 🔗 Law 🔗 Computing/Software 🔗 Computing/Free and open-source software

Beerware is a somewhat tongue-in-cheek term for software released under a very relaxed license (beerware licensed software). It provides the end user with the right to use a particular program (or do anything else with the source code).

🔗 United States 🔗 International relations 🔗 Soviet Union 🔗 Agriculture 🔗 Trade 🔗 Soviet Union/economy of Russia

The great grain robbery was the July 1972 purchase of 10 million tons of grain (mainly wheat and corn) from the United States by the Soviet Union at subsidized prices, which caused global grain prices to soar. Crop shortfalls in 1971 and 1972 forced the Soviet Union to look abroad for grain, hoping to prevent famine or crisis. Soviet negotiators worked out a deal to buy grain on credit, but quickly exceeded their credit limit. The American negotiators did not realize that both the Soviets and the world grain market had suffered shortfalls, and thus chose to subsidize the purchase. The strategy backfired and intensified the crisis with global food prices rose at least 30%, and grain stockpiles were decimated.

Mental poker is the common name for a set of cryptographic problems that concerns playing a fair game over distance without the need for a trusted third party. The term is also applied to the theories surrounding these problems and their possible solutions. The name comes from the card game poker which is one of the games to which this kind of problem applies. Similar problems described as two party games are Blum's flipping a coin over a distance, Yao's Millionaires' Problem, and Rabin's oblivious transfer.

The problem can be described thus: "How can one allow only authorized actors to have access to certain information while not using a trusted arbiter?" (Eliminating the trusted third-party avoids the problem of trying to determine whether the third party can be trusted or not, and may also reduce the resources required.)

In poker, this could translate to: "How can we make sure no player is stacking the deck or peeking at other players' cards when we are shuffling the deck ourselves?". In a physical card game, this would be relatively simple if the players were sitting face to face and observing each other, at least if the possibility of conventional cheating can be ruled out. However, if the players are not sitting at the same location but instead are at widely separate locations and pass the entire deck between them (using the postal mail, for instance), this suddenly becomes very difficult. And for electronic card games, such as online poker, where the mechanics of the game are hidden from the user, this is impossible unless the method used is such that it cannot allow any party to cheat by manipulating or inappropriately observing the electronic "deck".

Several protocols for doing this have been suggested, the first by Adi Shamir, Ron Rivest and Len Adleman (the creators of the RSA-encryption protocol). This protocol was the first example of two parties conducting secure computation rather than secure message transmission, employing cryptography; later on due to leaking partial information in the original protocol, this led to the definition of semantic security by Shafi Goldwasser and Silvio Micali. The concept of multi-player mental poker was introduced in Moti Yung's 1984 book Cryptoprotocols. The area has later evolved into what is known as secure multi-party computation protocols (for two parties, and multi parties as well).