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In computer science, an algorithm is called non-blocking if failure or suspension of any thread cannot cause failure or suspension of another thread; for some operations, these algorithms provide a useful alternative to traditional blocking implementations. A non-blocking algorithm is lock-free if there is guaranteed system-wide progress, and wait-free if there is also guaranteed per-thread progress.

The word "non-blocking" was traditionally used to describe telecommunications networks that could route a connection through a set of relays "without having to re-arrange existing calls", see Clos network. Also, if the telephone exchange "is not defective, it can always make the connection", see nonblocking minimal spanning switch.

Wikiracing is a game using the online encyclopedia Wikipedia which focuses on traversing links from one page to another. It has many different variations and names, including The Wikipedia Game, Wikipedia Maze, Wikispeedia, Wikiwars, Wikipedia Ball, and Litner Ball. External websites have been created to facilitate the game.

The Seattle Times has recommended it as a good educational pastime for children and the Larchmont Gazette has said, "While I don't know any teenagers who would curl up with an encyclopedia for a good read, I hear that a lot are reading it in the process of playing the Wikipedia Game".

The Amazing Wiki Race has been an event at the TechOlympics and the Yale Freshman Olympics.

The average number of links separating any Wikipedia page from the United Kingdom page is 3.67. Other common houserules such as not using the United States page increase the difficulty of the game.

As of July 2019, a website and game known as The Wiki Game has been created, allowing players to Wikirace against each other in a server, for more points and recognition on the server. The game reached more recognition as Internet stars such as Game Grumps played it on their channels. There is a version on the App Store as well, in which players can do a variety of Wikirace styles from their phone.

An eigenface () is the name given to a set of eigenvectors when used in the computer vision problem of human face recognition. The approach of using eigenfaces for recognition was developed by Sirovich and Kirby (1987) and used by Matthew Turk and Alex Pentland in face classification. The eigenvectors are derived from the covariance matrix of the probability distribution over the high-dimensional vector space of face images. The eigenfaces themselves form a basis set of all images used to construct the covariance matrix. This produces dimension reduction by allowing the smaller set of basis images to represent the original training images. Classification can be achieved by comparing how faces are represented by the basis set.

Internet 0 is a low-speed physical layer designed to route 'IP over anything.' It was developed at MIT's Center for Bits and Atoms by Neil Gershenfeld, Raffi Krikorian, and Danny Cohen. When it was invented, a number of other proposals were being labelled as "internet 2." The name was chosen to emphasize that this was designed to be a slow, but very inexpensive internetworking system, and forestall "high-performance" comparison questions such as "how fast is it?"

Effectively, it would enable a platform for pervasive computing -- everything in a building could be on the same network to share data gathering and actuation. A light switch could turn on a light bulb by sending a packet to it, they can be linked together by the user.

In re Bilski, 545 F.3d 943, 88 U.S.P.Q.2d 1385 (Fed. Cir. 2008), was an en banc decision of the United States Court of Appeals for the Federal Circuit (CAFC) on the patenting of method claims, particularly business methods. The Federal Circuit court affirmed the rejection of the patent claims involving a method of hedging risks in commodities trading. The court also reiterated the machine-or-transformation test as the (meaning sole) applicable test for patent-eligible subject matter, and stated that the test in State Street Bank v. Signature Financial Group should no longer be relied upon.

The Supreme Court of the United States issued an opinion on appeal (as Bilski v. Kappos) that affirmed the judgment of the CAFC, but revised many aspects of the CAFC's decision. In its decision, handed down on June 28, 2010, the Supreme Court rejected the machine-or-transformation test as the sole test of process patent eligibility based on an interpretation of the language of § 101. The majority, however, had high praise for the Federal Circuit opinions, advising that "[s]tudents of patent law would be well advised to study these scholarly opinions."

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).

The Seven Bridges of Königsberg is a historically notable problem in mathematics. Its negative resolution by Leonhard Euler in 1736 laid the foundations of graph theory and prefigured the idea of topology.

The city of Königsberg in Prussia (now Kaliningrad, Russia) was set on both sides of the Pregel River, and included two large islands—Kneiphof and Lomse—which were connected to each other, or to the two mainland portions of the city, by seven bridges. The problem was to devise a walk through the city that would cross each of those bridges once and only once.

By way of specifying the logical task unambiguously, solutions involving either

1. reaching an island or mainland bank other than via one of the bridges, or
2. accessing any bridge without crossing to its other end

are explicitly unacceptable.

Euler proved that the problem has no solution. The difficulty he faced was the development of a suitable technique of analysis, and of subsequent tests that established this assertion with mathematical rigor.

The winter solstice, hiemal solstice or hibernal solstice, also known as midwinter, occurs when one of the Earth's poles has its maximum tilt away from the Sun. It happens twice yearly, once in each hemisphere (Northern and Southern). For that hemisphere, the winter solstice is the day with the shortest period of daylight and longest night of the year, when the Sun is at its lowest daily maximum elevation in the sky. At the pole, there is continuous darkness or twilight around the winter solstice. Its opposite is the summer solstice.

The winter solstice occurs during the hemisphere's winter. In the Northern Hemisphere, this is the December solstice (usually 21 or 22 December) and in the Southern Hemisphere, this is the June solstice (usually 20 or 21 June). Although the winter solstice itself lasts only a moment, the term sometimes refers to the day on which it occurs. Other names are "midwinter", the "extreme of winter" (Dongzhi), or the "shortest day". Traditionally, in many temperate regions, the winter solstice is seen as the middle of winter, but today in some countries and calendars, it is seen as the beginning of winter. In meteorology, winter is reckoned as beginning about three weeks before the winter solstice.

Since prehistory, the winter solstice has been seen as a significant time of year in many cultures, and has been marked by festivals and rituals. It marked the symbolic death and rebirth of the Sun. The seasonal significance of the winter solstice is in the reversal of the gradual lengthening of nights and shortening of days.

" '—All You Zombies—' " is a science fiction short story by American writer Robert A. Heinlein. It was written in one day, July 11, 1958, and first published in the March 1959 issue of Fantasy and Science Fiction magazine after being rejected by Playboy.

The story involves a number of paradoxes caused by time travel. In 1980, it was nominated for the Balrog Award for short fiction.

"'—All You Zombies—'" further develops themes explored by the author in a previous work: "By His Bootstraps", published some 18 years earlier. Some of the same elements also appear later in The Cat Who Walks Through Walls (1985), including the Circle of Ouroboros and the Temporal Corps.

The unusual title of the story, which includes both the quotation marks and dashes shown above, is a quotation from a sentence near the end of the story; the quotation is taken from the middle of the sentence, hence the dashes indicating edited text before and after the title.

The Tetrapharmakos (τετραφάρμακος) "four-part remedy" is a summary of the first four of the Κύριαι Δόξαι (Kuriai Doxai, the forty Epicurean Principal Doctrines given by Diogenes Laërtius in his Life of Epicurus) in Epicureanism, a recipe for leading the happiest possible life. They are recommendations to avoid anxiety or existential dread.

The "tetrapharmakos" was originally a compound of four drugs (wax, tallow, pitch and resin); the word has been used metaphorically by Roman-era Epicureans. to refer to the four remedies for healing the soul.