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🔗 Aviation 🔗 Aviation/aircraft 🔗 Aviation/rotorcraft

The cyclogyro, or cyclocopter, is an aircraft configuration that uses a horizontal-axis cyclorotor as a rotor wing to provide lift and sometimes also propulsion and control. In principle, the cyclogyro is capable of vertical take off and landing and hovering performance like a helicopter, while potentially benefiting from some of the advantages of a fixed-wing aircraft.

The cyclogyro is distinct from the Flettner airplane which uses a cylindrical wing rotor to harness the Magnus effect.

🔗 Mathematics 🔗 Economics 🔗 Politics 🔗 Game theory

In game theory, the Nash equilibrium, named after the mathematician John Forbes Nash Jr., is a proposed solution of a non-cooperative game involving two or more players in which each player is assumed to know the equilibrium strategies of the other players, and no player has anything to gain by changing only their own strategy.

In terms of game theory, if each player has chosen a strategy, and no player can benefit by changing strategies while the other players keep theirs unchanged, then the current set of strategy choices and their corresponding payoffs constitutes a Nash equilibrium.

Stated simply, Alice and Bob are in Nash equilibrium if Alice is making the best decision she can, taking into account Bob's decision while his decision remains unchanged, and Bob is making the best decision he can, taking into account Alice's decision while her decision remains unchanged. Likewise, a group of players are in Nash equilibrium if each one is making the best decision possible, taking into account the decisions of the others in the game as long as the other parties' decisions remain unchanged.

Nash showed that there is a Nash equilibrium for every finite game: see further the article on strategy.

🔗 Philosophy 🔗 Philosophy/Logic 🔗 Business 🔗 Marketing & Advertising 🔗 Linguistics 🔗 Philosophy/Philosophy of language 🔗 Linguistics/Philosophy of language 🔗 Etymology

Bullshit (also bullcrap) is a common English expletive which may be shortened to the euphemism bull or the initialism B.S. In British English, "bollocks" is a comparable expletive. It is mostly a slang term and a profanity which means "nonsense", especially as a rebuke in response to communication or actions viewed as deceptive, misleading, disingenuous, unfair or false. As with many expletives, the term can be used as an interjection, or as many other parts of speech, and can carry a wide variety of meanings. A person who communicates nonsense on a given subject may be referred to as a "bullshit artist".

In philosophy and psychology of cognition the term "bullshit" is sometimes used to specifically refer to statements produced without particular concern of truth, to distinguish from a deliberate, manipulative lie intended to subvert the truth.

While the word is generally used in a deprecatory sense, it may imply a measure of respect for language skills or frivolity, among various other benign usages. In philosophy, Harry Frankfurt, among others, analyzed the concept of bullshit as related to, but distinct from, lying.

As an exclamation, "Bullshit!" conveys a measure of dissatisfaction with something or someone, but this usage need not be a comment on the truth of the matter.

🔗 Biography 🔗 Latter Day Saint movement

Mark William Hofmann (born December 7, 1954) is an American counterfeiter, forger, and convicted murderer. Widely regarded as one of the most accomplished forgers in history, Hofmann is especially noted for his creation of documents related to the history of the Latter Day Saint movement. When his schemes began to unravel, he constructed bombs to murder two people in Salt Lake City, Utah.

🔗 Plants 🔗 Ireland

The Hungry Tree is a tree in the grounds of the King's Inns in Dublin, Republic of Ireland. An otherwise unremarkable specimen of the London plane, it has become known for having partially consumed a nearby park bench. It has become a tourist attraction and is frequently photographed. The Hungry Tree was the subject of a campaign by Green Party politician Ciarán Cuffe to ensure its preservation.

🔗 Computing 🔗 Computing/Software

dvdisaster is a computer program aimed to enhance data survivability on optical discs by creating error detection and correction data, which is used for data recovery. dvdisaster works exclusively at the image level. This program can be used either to generate Error-Correcting Code (ECC) data from an existing media or to augment an ISO image with ECC data prior to being written onto a medium. dvdisaster is free software available under the GNU General Public License.

🔗 Germany 🔗 Socialism 🔗 Germany/GDR

The East German coffee crisis refers to shortages of coffee in the late 1970s in East Germany caused by a poor harvest and unstable commodity prices, severely limiting the government's ability to buy coffee on the world markets. As a consequence, the East German government increased its engagement in Africa and Asia, exporting weapons and equipment to coffee-producing nations.

🔗 Systems 🔗 Systems/Chaos theory

In mathematics, the lakes of Wada (和田の湖, Wada no mizuumi) are three disjoint connected open sets of the plane or open unit square with the counterintuitive property that they all have the same boundary. In other words, for any point selected on the boundary of one of the lakes, the other two lakes' boundaries also contain that point.

More than two sets with the same boundary are said to have the Wada property; examples include Wada basins in dynamical systems. This property is rare in real-world systems.

The lakes of Wada were introduced by Kunizō Yoneyama (1917, page 60), who credited the discovery to Takeo Wada. His construction is similar to the construction by Brouwer (1910) of an indecomposable continuum, and in fact it is possible for the common boundary of the three sets to be an indecomposable continuum.

🔗 Computing 🔗 Electronics 🔗 Electrical engineering

An asynchronous circuit, or self-timed circuit, is a sequential digital logic circuit which is not governed by a clock circuit or global clock signal. Instead it often uses signals that indicate completion of instructions and operations, specified by simple data transfer protocols. This type of circuit is contrasted with synchronous circuits, in which changes to the signal values in the circuit are triggered by repetitive pulses called a clock signal. Most digital devices today use synchronous circuits. However asynchronous circuits have the potential to be faster, and may also have advantages in lower power consumption, lower electromagnetic interference, and better modularity in large systems. Asynchronous circuits are an active area of research in digital logic design.

🔗 Computer science

Pearson hashing is a hash function designed for fast execution on processors with 8-bit registers. Given an input consisting of any number of bytes, it produces as output a single byte that is strongly dependent on every byte of the input. Its implementation requires only a few instructions, plus a 256-byte lookup table containing a permutation of the values 0 through 255.

This hash function is a CBC-MAC that uses an 8-bit substitution cipher implemented via the substitution table. An 8-bit cipher has negligible cryptographic security, so the Pearson hash function is not cryptographically strong, but it is useful for implementing hash tables or as a data integrity check code, for which purposes it offers these benefits:

• It is extremely simple.
• It executes quickly on resource-limited processors.
• There is no simple class of inputs for which collisions (identical outputs) are especially likely.
• Given a small, privileged set of inputs (e.g., reserved words for a compiler), the permutation table can be adjusted so that those inputs yield distinct hash values, producing what is called a perfect hash function.
• Two input strings differing by exactly one character never collide. E.g., applying the algorithm on the strings ABC and AEC will never produce the same value.

One of its drawbacks when compared with other hashing algorithms designed for 8-bit processors is the suggested 256 byte lookup table, which can be prohibitively large for a small microcontroller with a program memory size on the order of hundreds of bytes. A workaround to this is to use a simple permutation function instead of a table stored in program memory. However, using a too simple function, such as T[i] = 255-i, partly defeats the usability as a hash function as anagrams will result in the same hash value; using a too complex function, on the other hand, will affect speed negatively. Using a function rather than a table also allows extending the block size. Such functions naturally have to be bijective, like their table variants.

The algorithm can be described by the following pseudocode, which computes the hash of message C using the permutation table T:

algorithm pearson hashing is
    h := 0

    for each c in C loop
        h := T[ h xor c ]
    end loop

    return h

The hash variable (h) may be initialized differently, e.g. to the length of the data (C) modulo 256; this particular choice is used in the Python implementation example below.