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Epimenides paradox

The Epimenides paradox reveals a problem with self-reference in logic. It is named after the Cretan philosopher Epimenides of Knossos (alive circa 600 BC) who is credited with the original statement. A typical description of the problem is given in the book Gödel, Escher, Bach, by Douglas Hofstadter:

"Epimenides was a Cretan who made the immortal statement: 'All Cretans are liars.'"

A paradox of self-reference arises when one considers whether it is possible for Epimenides to have spoken the truth.

Mythology of lying Cretans
According to Ptolemaeus Chennus, Thetis and Medea had once argued in Thessaly over which was the most beautiful; they appointed the Cretan Idomeneus as the judge, who gave the victory to Thetis. In her anger, Medea called all Cretans liars, and cursed them to never say the truth.

Logical paradox
Thomas Fowler (1869) states the paradox as follows: "Epimenides the Cretan says, 'that all the Cretans are liars,' but Epimenides is himself a Cretan; therefore he is himself a liar. But if he is a liar, what he says is untrue, and consequently, the Cretans are veracious; but Epimenides is a Cretan, and therefore what he says is true; saying the Cretans are liars, Epimenides is himself a liar, and what he says is untrue. Thus we may go on alternately proving that Epimenides and the Cretans are truthful and untruthful."

If we assume the statement is false and that Epimenides is lying about all Cretans being liars, then there must exist at least one Cretan who is honest. This does not lead to a contradiction since it is not required that this Cretan be Epimenides. This means that Epimenides can say the false statement that all Cretans are liars while knowing at least one honest Cretan and lying about this particular Cretan. Hence, from the assumption that the statement is false, it does not follow that the statement is true. So we can avoid a paradox as seeing the statement "all Cretans are liars" as a false statement, which is made by a lying Cretan, Epimenides. The mistake made by Thomas Fowler (and many other people) above is to think that the negation of "all Cretans are liars" is "all Cretans are honest" (a paradox) when in fact the negation is "there exists a Cretan who is honest", or "not all Cretans are liars". The Epimenides paradox can be slightly modified as to not allow the kind of solution described above, as it was in the first paradox of Eubulides but instead leading to a non-avoidable self-contradiction. Paradoxical versions of the Epimenides problem are closely related to a class of more difficult logical problems, including the liar paradox, Socratic paradox and the Burali-Forti paradox, all of which have self-reference in common with Epimenides. The Epimenides paradox is usually classified as a variation on the liar paradox, and sometimes the two are not distinguished. The study of self-reference led to important developments in logic and mathematics in the twentieth century.

In other words, it is not a paradox once one realizes "All Cretans are liars" being untrue only means "Not all Cretans are liars" instead of the assumption that "All Cretans are honest".

Perhaps better put, for "All Cretans are liars" to be a true statement, it does not mean that all Cretans must lie all the time. In fact, Cretans could tell the truth quite often, but still all be liars in the sense that liars are people prone to deception for dishonest gain. Considering that "All Cretans are liars" has been seen as a paradox only since the 19th century, this seems to resolve the alleged paradox. If 'all Cretans are continuous liars' is actually true, then asking a Cretan if they are honest would always elicit the dishonest answer 'yes'. So arguably the original proposition is not so much paradoxical as invalid.

A contextual reading of the contradiction may also provide an answer to the paradox. The original phrase, "The Cretans, always liars, evil beasts, idle bellies!" asserts not an intrinsic paradox, but rather an opinion of the Cretans from Epimenides. A stereotyping of his people not intended to be an absolute statement about the people as a whole. Rather it is a claim made about their position regarding their religious beliefs and socio-cultural attitudes. Within the context of his poem the phrase is specific to a certain belief, a context that Callimachus repeats in his poem regarding Zeus. Further, a more poignant answer to the paradox is simply that to be a liar is to state falsehoods, nothing in the statement asserts everything said is false, but rather they're "always" lying. This is not an absolute statement of fact and thus we cannot conclude there's a true contradiction made by Epimenides with this statement.

Origin of the phrase
Epimenides was a 6th-century BC philosopher and religious prophet who, against the general sentiment of Crete, proposed that Zeus was immortal, as in the following poem:

Denying the immortality of Zeus, then, was the lie of the Cretans.

The phrase "Cretans, always liars" was quoted by the poet Callimachus in his Hymn to Zeus, with the same theological intent as Epimenides:

Emergence as a logical contradiction
The logical inconsistency of a Cretan asserting all Cretans are always liars may not have occurred to Epimenides, nor to Callimachus, who both used the phrase to emphasize their point, without irony, perhaps meaning that all Cretans lie routinely, but not exclusively.

In the 1st century AD, the quote is mentioned by the author of the Epistle to Titus as having been spoken truly by "one of their own prophets."

Clement of Alexandria, in the late 2nd century AD, fails to indicate that the concept of logical paradox is an issue:

During the early 4th century, Saint Augustine restates the closely related liar paradox in Against the Academicians (III.13.29), but without mentioning Epimenides.

In the Middle Ages, many forms of the liar paradox were studied under the heading of insolubilia, but these were not explicitly associated with Epimenides.

Finally, in 1740, the second volume of Pierre Bayle's Dictionnaire Historique et Critique explicitly connects Epimenides with the paradox, though Bayle labels the paradox a "sophisme".

References by other authors
All of the works of Epimenides are now lost, and known only through quotations by other authors. The quotation from the Cretica of Epimenides is given by R.N. Longenecker, "Acts of the Apostles", in volume 9 of The Expositor's Bible Commentary, Frank E. Gaebelein, editor (Grand Rapids, Michigan: Zondervan Corporation, 1976–1984), page 476. Longenecker in turn cites M.D. Gibson, Horae Semiticae X (Cambridge: Cambridge University Press, 1913), page 40, "in Syriac". Longenecker states the following in a footnote:

"The Syr. version of the quatrain comes to us from the Syr. church father Isho'dad of Merv (probably based on the work of Theodore of Mopsuestia), which J.R. Harris translated back into Gr. in Exp ["The Expositor"] 7 (1907), p 336."

An oblique reference to Epimenides in the context of logic appears in "The Logical Calculus" by W. E. Johnson, Mind (New Series), volume 1, number 2 (April, 1892), pages 235–250. Johnson writes in a footnote,

"Compare, for example, such occasions for fallacy as are supplied by "Epimenides is a liar" or "That surface is red," which may be resolved into "All or some statements of Epimenides are false," "All or some of the surface is red.""

The Epimenides paradox appears explicitly in "Mathematical Logic as Based on the Theory of Types", by Bertrand Russell, in the American Journal of Mathematics, volume 30, number 3 (July, 1908), pages 222–262, which opens with the following:

"The oldest contradiction of the kind in question is the Epimenides. Epimenides the Cretan said that all Cretans were liars, and all other statements made by Cretans were certainly lies. Was this a lie?"

In that article, Russell uses the Epimenides paradox as the point of departure for discussions of other problems, including the Burali-Forti paradox and the paradox now called Russell's paradox. Since Russell, the Epimenides paradox has been referenced repeatedly in logic. Typical of these references is Gödel, Escher, Bach by Douglas Hofstadter, which accords the paradox a prominent place in a discussion of self-reference.

It is also believed that the "Cretan tales" told by Odysseus in The Odyssey by Homer are a reference to this paradox.

In The Second Sex (1949) Simone de Beauvoir writes "I think certain women are still best suited to elucidate the situation of women. It is a sophism to claim that Epimenides should be enclosed within the concept of Cretan and all Cretans within the concept of liar: it is not a mysterious essence that dictates good or bad faith to men and women".

title: Epimenides paradox


text:
Engine

4StrokeEngine Ortho 3D Small.gif gasoline-fueled internal combustion cycle with electrical ignition source: 1. Induction (Fuel enters)

2. Compression

3. Ignition (Fuel is burnt)

4. Emission (Exhaust out)]]

An engine or motor is a machine designed to convert one or more forms of energy into mechanical energy.

Available energy sources include potential energy (e.g. energy of the Earth's gravitational field as exploited in hydroelectric power generation), heat energy (e.g. geothermal), chemical energy, electric potential and nuclear energy (from nuclear fission or nuclear fusion). Many of these processes generate heat as an intermediate energy form, so heat engines have special importance. Some natural processes, such as atmospheric convection cells convert environmental heat into motion (e.g. in the form of rising air currents). Mechanical energy is of particular importance in transportation, but also plays a role in many industrial processes such as cutting, grinding, crushing, and mixing.

Mechanical heat engines convert heat into work via various thermodynamic processes. The internal combustion engine is perhaps the most common example of a mechanical heat engine, in which heat from the combustion of a fuel causes rapid pressurisation of the gaseous combustion products in the combustion chamber, causing them to expand and drive a piston, which turns a crankshaft. Unlike internal combustion engines, a reaction engine (such as a jet engine) produces thrust by expelling reaction mass, in accordance with Newton's third law of motion.

Apart from heat engines, electric motors convert electrical energy into mechanical motion, pneumatic motors use compressed air, and clockwork motors in wind-up toys use elastic energy. In biological systems, molecular motors, like myosins in muscles, use chemical energy to create forces and ultimately motion (a chemical engine, but not a heat engine).

Chemical heat engines which employ air (ambient atmospheric gas) as a part of the fuel reaction are regarded as airbreathing engines. Chemical heat engines designed to operate outside of Earth's atmosphere (e.g. rockets, deeply submerged submarines) need to carry an additional fuel component called the oxidizer (although there exist super-oxidizers suitable for use in rockets, such as fluorine, a more powerful oxidant than oxygen itself); or the application needs to obtain heat by non-chemical means, such as by means of nuclear reactions.

Emission/Byproducts
All chemically fueled heat engines emit exhaust gases. The cleanest engines emit water only. Strict zero-emissions generally means zero emissions other than water and water vapour. Only heat engines which combust pure hydrogen (fuel) and pure oxygen (oxidizer) achieve zero-emission by a strict definition (in practice, one type of rocket engine). If hydrogen is burnt in combination with air (all airbreathing engines), a side reaction occurs between atmospheric oxygen and atmospheric nitrogen resulting in small emissions of. If a hydrocarbon (such as alcohol or gasoline) is burnt as fuel,, a greenhouse gas, is emitted. Hydrogen and oxygen from air can be reacted into water by a fuel cell without side production of, but this is an electrochemical engine not a heat engine.

Terminology
The word engine derives from Old French, from the Latin ingenium–the root of the word. Pre-industrial weapons of war, such as catapults, trebuchets and battering rams, were called siege engines, and knowledge of how to construct them was often treated as a military secret. The word gin, as in cotton gin, is short for engine. Most mechanical devices invented during the industrial revolution were described as engines—the steam engine being a notable example. However, the original steam engines, such as those by Thomas Savery, were not mechanical engines but pumps. In this manner, a fire engine in its original form was merely a water pump, with the engine being transported to the fire by horses.

In modern usage, the term engine typically describes devices, like steam engines and internal combustion engines, that burn or otherwise consume fuel to perform mechanical work by exerting a torque or linear force (usually in the form of thrust). Devices converting heat energy into motion are commonly referred to simply as engines. Examples of engines which exert a torque include the familiar automobile gasoline and diesel engines, as well as turboshafts. Examples of engines which produce thrust include turbofans and rockets.

When the internal combustion engine was invented, the term motor was initially used to distinguish it from the steam engine—which was in wide use at the time, powering locomotives and other vehicles such as steam rollers. The term motor derives from the Latin verb which means 'to set in motion', or 'maintain motion'. Thus a motor is a device that imparts motion.

Motor and engine are interchangeable in standard English. In some engineering jargons, the two words have different meanings, in which engine is a device that burns or otherwise consumes fuel, changing its chemical composition, and a motor is a device driven by electricity, air, or hydraulic pressure, which does not change the chemical composition of its energy source. However, rocketry uses the term rocket motor, even though they consume fuel.

A heat engine may also serve as a prime mover—a component that transforms the flow or changes in pressure of a fluid into mechanical energy. An automobile powered by an internal combustion engine may make use of various motors and pumps, but ultimately all such devices derive their power from the engine. Another way of looking at it is that a motor receives power from an external source, and then converts it into mechanical energy, while an engine creates power from pressure (derived directly from the explosive force of combustion or other chemical reaction, or secondarily from the action of some such force on other substances such as air, water, or steam).

Antiquity
Simple machines, such as the club and oar (examples of the lever), are prehistoric. More complex engines using human power, animal power, water power, wind power and even steam power date back to antiquity. Human power was focused by the use of simple engines, such as the capstan, windlass or treadmill, and with ropes, pulleys, and block and tackle arrangements; this power was transmitted usually with the forces multiplied and the speed reduced. These were used in cranes and aboard ships in Ancient Greece, as well as in mines, water pumps and siege engines in Ancient Rome. The writers of those times, including Vitruvius, Frontinus and Pliny the Elder, treat these engines as commonplace, so their invention may be more ancient. By the 1st century AD, cattle and horses were used in mills, driving machines similar to those powered by humans in earlier times.

According to Strabo, a water-powered mill was built in Kaberia of the kingdom of Mithridates during the 1st century BC. Use of water wheels in mills spread throughout the Roman Empire over the next few centuries. Some were quite complex, with aqueducts, dams, and sluices to maintain and channel the water, along with systems of gears, or toothed-wheels made of wood and metal to regulate the speed of rotation. More sophisticated small devices, such as the Antikythera Mechanism used complex trains of gears and dials to act as calendars or predict astronomical events. In a poem by Ausonius in the 4th century AD, he mentions a stone-cutting saw powered by water. Hero of Alexandria is credited with many such wind and steam powered machines in the 1st century AD, including the Aeolipile and the vending machine, often these machines were associated with worship, such as animated altars and automated temple doors.

Medieval
Medieval Muslim engineers employed gears in mills and water-raising machines, and used dams as a source of water power to provide additional power to watermills and water-raising machines. In the medieval Islamic world, such advances made it possible to mechanize many industrial tasks previously carried out by manual labour.

In 1206, al-Jazari employed a crank-conrod system for two of his water-raising machines. A rudimentary steam turbine device was described by Taqi al-Din in 1551 and by Giovanni Branca in 1629.

In the 13th century, the solid rocket motor was invented in China. Driven by gunpowder, this simplest form of internal combustion engine was unable to deliver sustained power, but was useful for propelling weaponry at high speeds towards enemies in battle and for fireworks. After invention, this innovation spread throughout Europe.

Industrial Revolution
The Watt steam engine was the first type of steam engine to make use of steam at a pressure just above atmospheric to drive the piston helped by a partial vacuum. Improving on the design of the 1712 Newcomen steam engine, the Watt steam engine, developed sporadically from 1763 to 1775, was a great step in the development of the steam engine. Offering a dramatic increase in fuel efficiency, James Watt's design became synonymous with steam engines, due in no small part to his business partner, Matthew Boulton. It enabled rapid development of efficient semi-automated factories on a previously unimaginable scale in places where waterpower was not available. Later development led to steam locomotives and great expansion of railway transportation.

As for internal combustion piston engines, these were tested in France in 1807 by de Rivaz and independently, by the Niépce brothers. They were theoretically advanced by Carnot in 1824. In 1853–57 Eugenio Barsanti and Felice Matteucci invented and patented an engine using the free-piston principle that was possibly the first 4-cycle engine.

The invention of an internal combustion engine which was later commercially successful was made during 1860 by Etienne Lenoir.

In 1877, the Otto cycle was capable of giving a far higher power-to-weight ratio than steam engines and worked much better for many transportation applications such as cars and aircraft.

Automobiles
The first commercially successful automobile, created by Karl Benz, added to the interest in light and powerful engines. The lightweight gasoline internal combustion engine, operating on a four-stroke Otto cycle, has been the most successful for light automobiles, while the thermally more-efficient Diesel engine is used for trucks and buses. However, in recent years, turbocharged Diesel engines have become increasingly popular in automobiles, especially outside of the United States, even for quite small cars.

Horizontally-opposed pistons
In 1896, Karl Benz was granted a patent for his design of the first engine with horizontally opposed pistons. His design created an engine in which the corresponding pistons move in horizontal cylinders and reach top dead center simultaneously, thus automatically balancing each other with respect to their individual momentum. Engines of this design are often referred to as “flat” or “boxer” engines due to their shape and low profile. They were used in the Volkswagen Beetle, the Citroën 2CV, some Porsche and Subaru cars, many BMW and Honda motorcycles. Opposed four- and six-cylinder engines continue to be used as a power source in small, propeller-driven aircraft.

Advancement
The continued use of internal combustion engines in automobiles is partly due to the improvement of engine control systems, such as on-board computers providing engine management processes, and electronically controlled fuel injection. Forced air induction by turbocharging and supercharging have increased the power output of smaller displacement engines that are lighter in weight and more fuel-efficient at normal cruise power.. Similar changes have been applied to smaller Diesel engines, giving them almost the same performance characteristics as gasoline engines. This is especially evident with the popularity of smaller diesel engine-propelled cars in Europe. Diesel engines produce lower hydrocarbon and emissions, but greater particulate and  pollution, than gasoline engines. Diesel engines are also 40% more fuel efficient than comparable gasoline engines.

Increasing power
In the first half of the 20th century, a trend of increasing engine power occurred, particularly in the U.S models. Design changes incorporated all known methods of increasing engine capacity, including increasing the pressure in the cylinders to improve efficiency, increasing the size of the engine, and increasing the rate at which the engine produces work. The higher forces and pressures created by these changes created engine vibration and size problems that led to stiffer, more compact engines with V and opposed cylinder layouts replacing longer straight-line arrangements.

Combustion efficiency
Optimal combustion efficiency in passenger vehicles is reached with a coolant temperature of around 230 F.

Engine configuration
Earlier automobile engine development produced a much larger range of engines than is in common use today. Engines have ranged from 1- to 16-cylinder designs with corresponding differences in overall size, weight, engine displacement, and cylinder bores. Four cylinders and power ratings from 19 to 120 hp (14 to 90 kW) were followed in a majority of the models. Several three-cylinder, two-stroke-cycle models were built while most engines had straight or in-line cylinders. There were several V-type models and horizontally opposed two- and four-cylinder makes too. Overhead camshafts were frequently employed. The smaller engines were commonly air-cooled and located at the rear of the vehicle; compression ratios were relatively low. The 1970s and 1980s saw an increased interest in improved fuel economy, which caused a return to smaller V-6 and four-cylinder layouts, with as many as five valves per cylinder to improve efficiency. The Bugatti Veyron 16.4 operates with a W16 engine, meaning that two V8 cylinder layouts are positioned next to each other to create the W shape sharing the same crankshaft.

The largest internal combustion engine ever built is the Wärtsilä-Sulzer RTA96-C, a 14-cylinder, 2-stroke turbocharged diesel engine that was designed to power the Emma Mærsk, the largest container ship in the world when launched in 2006. This engine has a mass of 2,300 tonnes, and when running at 102 rpm (1.7 Hz) produces over 80 MW, and can use up to 250 tonnes of fuel per day.

Types
An engine can be put into a category according to two criteria: the form of energy it accepts in order to create motion, and the type of motion it outputs.

Combustion engine
Combustion engines are heat engines driven by the heat of a combustion process.

Internal combustion engine
The internal combustion engine is an engine in which the combustion of a fuel (generally, fossil fuel) occurs with an oxidizer (usually air) in a combustion chamber. In an internal combustion engine the expansion of the high temperature and high pressure gases, which are produced by the combustion, directly applies force to components of the engine, such as the pistons or turbine blades or a nozzle, and by moving it over a distance, generates mechanical work.

External combustion engine
An external combustion engine (EC engine) is a heat engine where an internal working fluid is heated by combustion of an external source, through the engine wall or a heat exchanger. The fluid then, by expanding and acting on the mechanism of the engine produces motion and usable work. The fluid is then cooled, compressed and reused (closed cycle), or (less commonly) dumped, and cool fluid pulled in (open cycle air engine).

"Combustion" refers to burning fuel with an oxidizer, to supply the heat. Engines of similar (or even identical) configuration and operation may use a supply of heat from other sources such as nuclear, solar, geothermal or exothermic reactions not involving combustion; but are not then strictly classed as external combustion engines, but as external thermal engines.

The working fluid can be a gas as in a Stirling engine, or steam as in a steam engine or an organic liquid such as n-pentane in an Organic Rankine cycle. The fluid can be of any composition; gas is by far the most common, although even single-phase liquid is sometimes used. In the case of the steam engine, the fluid changes phases between liquid and gas.

Air-breathing combustion engines
Air-breathing combustion engines are combustion engines that use the oxygen in atmospheric air to oxidise ('burn') the fuel, rather than carrying an oxidiser, as in a rocket. Theoretically, this should result in a better specific impulse than for rocket engines.

A continuous stream of air flows through the air-breathing engine. This air is compressed, mixed with fuel, ignited and expelled as the exhaust gas. In reaction engines, the majority of the combustion energy (heat) exits the engine as exhaust gas, which provides thrust directly.

Typical air-breathing engines include:
 * Examples
 * Reciprocating engine
 * Steam engine
 * Gas turbine
 * Airbreathing jet engine
 * Turbo-propeller engine
 * Pulse detonation engine
 * Pulse jet
 * Ramjet
 * Scramjet
 * Liquid air cycle engine/Reaction Engines SABRE.

Environmental effects
The operation of engines typically has a negative impact upon air quality and ambient sound levels. There has been a growing emphasis on the pollution producing features of automotive power systems. This has created new interest in alternate power sources and internal-combustion engine refinements. Though a few limited-production battery-powered electric vehicles have appeared, they have not proved competitive owing to costs and operating characteristics. In the 21st century the diesel engine has been increasing in popularity with automobile owners. However, the gasoline engine and the Diesel engine, with their new emission-control devices to improve emission performance, have not yet been significantly challenged. A number of manufacturers have introduced hybrid engines, mainly involving a small gasoline engine coupled with an electric motor and with a large battery bank, these are starting to become a popular option because of their environment awareness.

Air quality
Exhaust gas from a spark ignition engine consists of the following: nitrogen 70 to 75% (by volume), water vapor 10 to 12%, carbon dioxide 10 to 13.5%, hydrogen 0.5 to 2%, oxygen 0.2 to 2%, carbon monoxide: 0.1 to 6%, unburnt hydrocarbons and partial oxidation products (e.g. aldehydes) 0.5 to 1%, nitrogen monoxide 0.01 to 0.4%, nitrous oxide <100 ppm, sulfur dioxide 15 to 60 ppm, traces of other compounds such as fuel additives and lubricants, also halogen and metallic compounds, and other particles. Carbon monoxide is highly toxic, and can cause carbon monoxide poisoning, so it is important to avoid any build-up of the gas in a confined space. Catalytic converters can reduce toxic emissions, but not eliminate them. Also, resulting greenhouse gas emissions, chiefly carbon dioxide, from the widespread use of engines in the modern industrialized world is contributing to the global greenhouse effect – a primary concern regarding global warming.

Non-combusting heat engines
Some engines convert heat from noncombustive processes into mechanical work, for example a nuclear power plant uses the heat from the nuclear reaction to produce steam and drive a steam engine, or a gas turbine in a rocket engine may be driven by decomposing hydrogen peroxide. Apart from the different energy source, the engine is often engineered much the same as an internal or external combustion engine.

Another group of noncombustive engines includes thermoacoustic heat engines (sometimes called "TA engines") which are thermoacoustic devices that use high-amplitude sound waves to pump heat from one place to another, or conversely use a heat difference to induce high-amplitude sound waves. In general, thermoacoustic engines can be divided into standing wave and travelling wave devices.

Stirling engines can be another form of non-combustive heat engine. They use the Stirling thermodynamic cycle to convert heat into work. An example is the alpha type Stirling engine, whereby gas flows, via a recuperator, between a hot cylinder and a cold cylinder, which are attached to reciprocating pistons 90° out of phase. The gas receives heat at the hot cylinder and expands, driving the piston that turns the crankshaft. After expanding and flowing through the recuperator, the gas rejects heat at the cold cylinder and the ensuing pressure drop leads to its compression by the other (displacement) piston, which forces it back to the hot cylinder.

Non-thermal chemically powered motor
Non-thermal motors usually are powered by a chemical reaction, but are not heat engines. Examples include:
 * Molecular motor – motors found in living things
 * Synthetic molecular motor.

Electric motor
An electric motor uses electrical energy to produce mechanical energy, usually through the interaction of magnetic fields and current-carrying conductors. The reverse process, producing electrical energy from mechanical energy, is accomplished by a generator or dynamo. Traction motors used on vehicles often perform both tasks. Electric motors can be run as generators and vice versa, although this is not always practical. Electric motors are ubiquitous, being found in applications as diverse as industrial fans, blowers and pumps, machine tools, household appliances, power tools, and disk drives. They may be powered by direct current (for example a battery powered portable device or motor vehicle), or by alternating current from a central electrical distribution grid. The smallest motors may be found in electric wristwatches. Medium-size motors of highly standardized dimensions and characteristics provide convenient mechanical power for industrial uses. The very largest electric motors are used for propulsion of large ships, and for such purposes as pipeline compressors, with ratings in the thousands of kilowatts. Electric motors may be classified by the source of electric power, by their internal construction, and by their application. The physical principle of production of mechanical force by the interactions of an electric current and a magnetic field was known as early as 1821. Electric motors of increasing efficiency were constructed throughout the 19th century, but commercial exploitation of electric motors on a large scale required efficient electrical generators and electrical distribution networks.

To reduce the electric energy consumption from motors and their associated carbon footprints, various regulatory authorities in many countries have introduced and implemented legislation to encourage the manufacture and use of higher efficiency electric motors. A well-designed motor can convert over 90% of its input energy into useful power for decades. When the efficiency of a motor is raised by even a few percentage points, the savings, in kilowatt hours (and therefore in cost), are enormous. The electrical energy efficiency of a typical industrial induction motor can be improved by: 1) reducing the electrical losses in the stator windings (e.g., by increasing the cross-sectional area of the conductor, improving the winding technique, and using materials with higher electrical conductivities, such as copper), 2) reducing the electrical losses in the rotor coil or casting (e.g., by using materials with higher electrical conductivities, such as copper), 3) reducing magnetic losses by using better quality magnetic steel, 4) improving the aerodynamics of motors to reduce mechanical windage losses, 5) improving bearings to reduce friction losses, and 6) minimizing manufacturing tolerances. For further discussion on this subject, see Premium efficiency).

By convention, electric engine refers to a railroad electric locomotive, rather than an electric motor.

Physically powered motor
Some motors are powered by potential or kinetic energy, for example some funiculars, gravity plane and ropeway conveyors have used the energy from moving water or rocks, and some clocks have a weight that falls under gravity. Other forms of potential energy include compressed gases (such as pneumatic motors), springs (clockwork motors) and elastic bands.

Historic military siege engines included large catapults, trebuchets, and (to some extent) battering rams were powered by potential energy.

Pneumatic motor
A pneumatic motor is a machine that converts potential energy in the form of compressed air into mechanical work. Pneumatic motors generally convert the compressed air to mechanical work through either linear or rotary motion. Linear motion can come from either a diaphragm or piston actuator, while rotary motion is supplied by either a vane type air motor or piston air motor. Pneumatic motors have found widespread success in the hand-held tool industry and continual attempts are being made to expand their use to the transportation industry. However, pneumatic motors must overcome efficiency deficiencies before being seen as a viable option in the transportation industry.

Hydraulic motor
A hydraulic motor derives its power from a pressurized liquid. This type of engine is used to move heavy loads and drive machinery.

Hybrid
Some motor units can have multiple sources of energy. For example, a plug-in hybrid electric vehicle's electric motor could source electricity from either a battery or from fossil fuels inputs via an internal combustion engine and a generator.

Performance
The following are used in the assessment of the performance of an engine.

Speed
Speed refers to crankshaft rotation in piston engines and the speed of compressor/turbine rotors and electric motor rotors. It is measured in revolutions per minute (rpm).

Thrust
Thrust is the force exerted on an airplane as a consequence of its propeller or jet engine accelerating the air passing through it. It is also the force exerted on a ship as a consequence of its propeller accelerating the water passing through it.

Torque
Torque is a turning moment on a shaft and is calculated by multiplying the force causing the moment by its distance from the shaft.

Power
Power is the measure of how fast work is done.

Efficiency
Efficiency is a proportion of useful energy output compared to total input.

Sound levels
Vehicle noise is predominantly from the engine at low vehicle speeds and from tires and the air flowing past the vehicle at higher speeds. Electric motors are quieter than internal combustion engines. Thrust-producing engines, such as turbofans, turbojets and rockets emit the greatest amount of noise due to the way their thrust-producing, high-velocity exhaust streams interact with the surrounding stationary air. Noise reduction technology includes intake and exhaust system mufflers (silencers) on gasoline and diesel engines and noise attenuation liners in turbofan inlets.

Engines by use
Particularly notable kinds of engines include:

 * Aircraft engine
 * Automobile engine
 * Model engine
 * Motorcycle engine
 * Marine propulsion engines such as Outboard motor
 * Non-road engine is the term used to define engines that are not used by vehicles on roadways.
 * Railway locomotive engine
 * Spacecraft propulsion engines such as Rocket engine
 * Traction engine

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Engine


text:
Talk:Esperanto

Slavic middle plane
Claude Piron's 1981 paper "Esperanto: european or asiatic language?" is cited to support the statement that Esperanto's grammar has more in common with Asian languages than with European ones. The paper's section titled "The Middle Plane" highlights several language features that are traditionally considered individually, but together can be construed as an additional linguistic structure that might be worth mentioning in this Wikipedia article.

This information could be added to the "Linguistic properties" section, in the "Classification" subsection, or in a new subsection called "Syntactic and semantic middle layer" or "Slavic influence".

Specifically, the paper's section "The Middle Plane" covers these aspects of the language: Dotyoyo (talk) 20:29, 17 April 2024 (UTC)
 * (1) Word order and style
 * (2) Syntax
 * (a) sequence of tenses
 * (b) obligatory reflexive
 * (c) distinction between modifying and predicative complements
 * (d) use of adverbial form with infinitival or clausal subject
 * (e) infinitive as prepositionless complement of noun
 * (f) asymmetry or constraints placed on the use of prepositions followed by infinitives
 * (3) Various non-Western aspects (distinctions of nuance)
 * (4) Obligatory distinction between transitivity and intransitivity
 * (5) Turns of phrase
 * (6) Semantic associations of roots, independent of source language
 * (7) Forms taken by loanwords
 * (8) The writing system (abbreviations, and lack of coarticulation effects)

 * The problem with Piron is that he is a language activist, and so his ideas should be checked against other secondary or tertiary sources. We can include this with an attribution to Piron, but we shouldn't give his ideas undue weight or prominence. Esperanto was designed to be an intermediary language, with a synthesis of different elements from its source languages, which makes attributing certain features to specific (groups of) source languages difficult, especially when these languages are in a continuum or a Sprachbund. It is for example often unclear whether a given feature is supposed to be classified as "Slavic-influenced" or more generally "Central European-influenced". TucanHolmes  (talk) 09:26, 18 April 2024 (UTC)

 * Thanks. I've added a sentence regarding Claude Piron's work to the end of the classification section. Dotyoyo (talk) 01:56, 28 April 2024 (UTC)
 * There's a reason this was removed from the article years ago. It only works if by "Asiatic" you mean "Russian". There's obviously a Slavic core, e.g. in semantics and phonology, that many people have commented on. But people wouldn't read 'Asiatic' to mean 'Russian', and if it's not that, what's "Asiatic grammar"? Topic-comment rather than subject-verb syntax? Verbs as adjectives? Verbs as adpositions? Nouns as adjectives? Nouns as adpositions? Noun classifiers? Actor-pivot morphology? Infixes? Aspect rather than tense? Lack of pronouns as a part of speech?
 * Non-Western, sure (i.e. Slavic). But "Asiatic" here is undefined and therefore meaningless. It doesn't add anything, only gives the false impression that it's saying something.
 * For "European", there is a vaguely defined Standard Average European that has some utility. But there's nothing comparable for Asia. — kwami (talk) 03:04, 28 April 2024 (UTC)

 * If we are mentioning Piron, we should be clear that he is an Esperanto activist, rather than an academic authority. His writings from his website should be treated as both self-published and heavily partisan.  That means that, if we're making exceptional claims (like, that Esperanto grammar is more Asian than European), then we need an exceptional source and Piron is not an exceptional source.  That applies even if we attribute him, because the mere fact of mentioning the claim gives it a credibility it doesn't obviously merit. Kahastok talk 11:07, 28 April 2024 (UTC)
 * WP:RS doesn't support this. There are several obvious problems with it. One is the claim that Z didn't know any "Asiatic" languages. Yet Hebrew and Aramaic are Asian languages. (Off-topic: I didn't know Z had studied Aramaic. I've never seen that before.) Another is the alleged "syntactic simplicity" that Eo shares with Chinese -- French and German are a lot simpler than Chinese is, at least to someone from a European background, and I doubt that Eo is 'syntactically simple' from a Chinese background either.
 * The Slavic connection is much more straightforward (and easily defined), and Piron's paper seems to have done a much better job with that. That's also something that a number of other people have noticed.
 * Claims that Eo is not "Indo-European" are usually made by people who have little to no idea what non-IE languages are actually like, and are never AFAICT accompanied by any data apart from a few (often inaccurate) generalizations. — kwami (talk) 20:46, 28 April 2024 (UTC)
 * Claude Piron knew both Esperanto and Chinese; he did professional interpretation for UNO then the WHO from English, Chinese, Spanish and Russian into French. Does this make him biased? Are PhDs who disparage Esperanto without ever having tried to learn it, or at least find out how it works, more "objective"? IMHO his arguments, as laid out in his free.fr user site (kept up unchanged by his friends since he died), make sense, and if one wants to refute them it should be with equally solid arguments from people who seriously knew Esperanto, not with a disparaging "Oh, he's an Esperanto activist, he doesn't count". For a serious opinion about, let's say, German, would you not require a reference from someone who seriously studied German? Then why should the opinions of those who seriously studied Esperanto be rejected as "Esperanto activists" when looking for a serious opinion about Esperanto?
 * This said, I believe that Claude Piron's opinions merit a mention, and that they should be attributed to him, not necessarily taken as "the truth from on high". I tried to do that in the article text. After reading Piron's article, I find his opinions interesting, to say the least. — Tonymec (talk) 21:59, 28 April 2024 (UTC)
 * Point about needed to know a language before opining on it. We shouldn't cite people who don't know the topic. Per WP:RS, they aren't acceptable as sources.
 * I would be curious as to how Piron determined that Chinese is syntactically simpler than French. Is it that in French you need to choose between être and avoir to govern a participle, or that in Chinese a word may function as either a verb or a preposition? The one isn't followed by European languages in general, whereas the other is nothing like Eo.
 * By "Asiatic", does he mean just Chinese? Or is Esperanto closer to Arabic, Sanskrit, Tagalog and Korean than it is to French? Does he have significant knowledge of "Asiatic" languages, so that he has some idea of what he's talking about? — kwami (talk) 22:37, 28 April 2024 (UTC)
 * Well, IIUC by reading the article, by "Asiatic" he meant "Chinese-like" i.e. not only Mandarin, but what one might call "Sinitic" languages. He draws a parallel between the way Chinese and Esperanto build derived words from constant "building blocks" as opposed to European languages where you have to learn the whole set of relations again for each basic root: for instance, the family ox, bull, cow, calf, beef, veal, etc. corresponds in Esperanto to bovo, virbovo, bovino, bovido, bovaĵo, bovidaĵo, etc., and the same set of prefixes and suffixes are used again with the radix ĉeval- to make the equivalents of horse, stallion, mare, foal, filly, and words nonexistent in English for "horse meat" and "foal meat" if they were needed. Similarly for every "family" of animals, where in English (or French or…) one has to learn the whole set again but in Esperanto (or, IIUC, Chinese) a single set of affixes works with all word roots, making the learning effort linear rather than quadratic in relation to the amount of concepts learned. Similarly for samlandano compatriot, samklasano classmate, samfamiliano relation (i.e. person of the same family) etc. where Esperanto and Chinese simply plop different roots between a common prefix and suffix to mean "member of the same <something>", while European languages need ad hoc variants in every case. — Tonymec (talk) 23:22, 28 April 2024 (UTC)
 * It's not syntax, then, but word-formation, and not Asiatic, but Chinese. (Sinitic is Chinese.) That makes much more sense, and I think is defensible. — kwami (talk) 23:31, 28 April 2024 (UTC)
 * The word Sinitic was unfortunate; I imagine Tonymec was thinking of e.g. Vietnamese, which is unrelated but (as I misunderstand) similarly isolating. —Tamfang (talk) 23:24, 29 April 2024 (UTC)
 * Also, don't delete tags from an article. They're there for a reason, and need to be resolved. — kwami (talk) 23:33, 28 April 2024 (UTC)
 * I thought I was giving the needed "clarification". — Tonymec (talk) 23:50, 28 April 2024 (UTC)
 * Deleting a citation-needed tag without providing a citation is not clarifying anything. — kwami (talk) 01:36, 29 April 2024 (UTC)
 * P.S. A single word root can be used in Esperanto as a preposition, a verb, an adjective, a noun, etc., with the single requirement that the result have a meaning. The difference with Chinese is that Esperanto nouns, verbs, adjectives, but not prepositions, need a specific "grammatical ending" to make their nature clear. For instance, the preposition per "by, through, by way of" has been reused as the verb per·i "to transmit, to be a go-between", then its present participle per·ant·o "go-between" reused in kotiz·per·ant·o "one who collects membership fees (for some association)", abon·per·ant·o "one who collects subscriptions (to some magazine)" etc. (where I use the middle dot · to separate the "invariable elements" used in word-building, the way Zamenhof did with dots, apostrophes, or the like, in the various different-language editions of his book The International Language). — Tonymec (talk) 23:50, 28 April 2024 (UTC)
 * A root is not a word. Peri is a derivation of per. It's a different word. In Mandarin, the single word yán can mean 'to follow', but is also equivalent to a preposition 'along'. It's ambiguous whether you're saying 'following the river' or 'along the river'. Esperanto is most emphatically not like that. — kwami (talk) 01:35, 29 April 2024 (UTC)

Zagreb

 * The Zagreb method is an Esperanto teaching method that was developed in Zagreb, Yugoslavia (present-day capital city of Croatia),

I believe Zagreb was the capital of Croatia then too, and would prefer
 * ... developed in Zagreb, capital of Croatia (then part of Yugoslavia),

or, even better, omit any direct mention of Croatia or Yugoslavia, whose relevance is not obvious. That's what links are for. —Tamfang (talk) 18:52, 8 May 2024 (UTC)

KTP

 * Historically, much music has been written in the language such as Kaj Tiel Plu.

Kaj Tiel Plu ('and so forth', literally 'and thus more') appears to be the name of a performing group, not a work. Either way, the sentence could be clearer. —Tamfang (talk) 00:43, 19 May 2024 (UTC)

 * By the way, there exists eo:Kategorio:Esperantaj muzikaj grupoj. —Tamfang (talk) 00:45, 19 May 2024 (UTC)

Islam

 * When did Ayatollah Khomeini recommend Esperanto as a international language?
 * When was the Esperanto Koran published?
 * Is Esperanto still used in Iran, especially in Qom?

MountVic127 (talk) 04:25, 28 May 2024 (UTC)

title: Talk:Esperanto


text:
Economic and monetary union

An economic and monetary union (EMU) is a type of trade bloc that features a combination of a common market, customs union, and monetary union. Established via a trade pact, an EMU constitutes the sixth of seven stages in the process of economic integration. An EMU agreement usually combines a customs union with a common market. A typical EMU establishes free trade and a common external tariff throughout its jurisdiction. It is also designed to protect freedom in the movement of goods, services, and people. This arrangement is distinct from a monetary union (e.g., the Latin Monetary Union), which does not usually involve a common market. As with the economic and monetary union established among the 27 member states of the European Union (EU), an EMU may affect different parts of its jurisdiction in different ways. Some areas are subject to separate customs regulations from other areas subject to the EMU. These various arrangements may be established in a formal agreement, or they may exist on a de facto basis. For example, not all EU member states use the Euro established by its currency union, and not all EU member states are part of the Schengen Area. Some EU members participate in both unions, and some in neither.

Territories of the United States, Australian External Territories and New Zealand territories each share a currency and, for the most part, the market of their respective mainland states. However, they are generally not part of the same customs territories.

History
Several countries initially attempted to form an EMU at the Hague Summit in 1969. Afterward, a "draft plan" was announced. During this time, the main member presiding over this decision was Pierre Werner, Prime Minister of Luxembourg. The decision to form the Economic and Monetary Union of the European Union (EMU) was accepted in December 1991, which later became part of the Maastricht Treaty (the Treaty on European Union).

Processes in the European EMU
The EMU involves four main activities.

The first responsibility is to be in charge of implementing effective monetary policy for the euro area with price stability. There is a group of economists whose only role is studying how to improve the monetary policy while maintaining price stability. They conduct research, and their results are presented to the leaders of the EMU. Thereafter, the role of the leaders is to find a suitable way to implement the economists' work into their country's policies. Maintaining price stability is a long-term goal for all states in the EU, due to the effects it might have on the Euro as a currency.

Secondly, the EMU must coordinate economic and fiscal policies in EU countries. They must find an equilibrium between the implementation of monetary and fiscal policies. They will advise countries to have greater coordination, even if that means having countries tightly coupled with looser monetary and tighter fiscal policy. Not coordinating the monetary market could result in risking an unpredictable situation. The EMU also deliberates on a mixed policy option, which has been shown to be beneficial in some empirical studies.

Thirdly, the EMU ensures that the single market runs smoothly. The member countries respect the decisions made by the EMU and ensure that their actions will be in favor of a stable market.

Finally, regulations of the EMU aid in supervising and monitoring financial institutions. There is an imperative need for all members of the EMU to act in unison. Therefore, the EMU has to have institutions supervising all the member states to protect the main aim of the EMU.

Roles of national governments
The economic roles of nations within the EMU are to:
 * control fiscal policy that concerns government budgets
 * control tax policies that determine how income is raised
 * control structural policies that determine pension systems, labor, and capital-market regulations

List of economic and monetary unions

 * Economic and Monetary Union of the European Union (EMU) (1999/2002) with the Euro for the Eurozone members
 * de facto the sovereign states in the OECS Eastern Caribbean Currency Union with the East Caribbean dollar in the CSME (2006)
 * de facto Switzerland–Liechtenstein

Previous EMUs

 * Monetary union of the Belgium–Luxembourg Economic Union (1922–2002), superseded by the European EMU.

title: Economic and monetary union


text:
European Environment Agency

The European Environment Agency (EEA) is the agency of the European Union (EU) which provides independent information on the environment.

Definition
The European Environment Agency (EEA) is the agency of the European Union (EU) which provides independent information on the environment. Its goal is to help those involved in developing, implementing and evaluating environmental policy, and to inform the general public.

Organization
The EEA was established by the European Economic Community (EEC) Regulation 1210/1990 (amended by EEC Regulation 933/1999 and EC Regulation 401/2009) and became operational in 1994, headquartered in Copenhagen, Denmark.

The agency is governed by a management board composed of representatives of the governments of its 32 member states, a European Commission representative and two scientists appointed by the European Parliament, assisted by its Scientific Committee.

The current Executive Director of the agency is Leena Ylä-Mononen, who has been appointed for a five-year term, starting on 1 June 2023. Ms Ylä-Mononen is the successor of professor Hans Bruyninckx.

Member countries
The member states of the European Union are members; however other states may become members of it by means of agreements concluded between them and the EU.

It was the first EU body to open its membership to the 13 candidate countries (pre-2004 enlargement).

The EEA has 32 member countries and six cooperating countries. The members are the 27 European Union member states together with Iceland, Liechtenstein, Norway, Switzerland and Turkey.

Since Brexit in 2020, the UK is not a member of the EU anymore and therefore not a member state of the EEA.

The six Western Balkan countries are cooperating countries: Albania, Bosnia and Herzegovina, Montenegro, North Macedonia, Serbia as well as Kosovo under the UN Security Council Resolution 1244/99. These cooperation activities are integrated into Eionet and are supported by the EU under the "Instrument for Pre-Accession Assistance".

The EEA is an active member of the EPA Network.

Reports, data and knowledge
The European Environment Agency (EEA) produces assessments based on quality-assured data on a wide range of issues from biodiversity, air quality, transport to climate change. These assessments are closely linked to the European Union's environment policies and legislation and help monitor progress in some areas and indicate areas where additional efforts are needed.

As required in its founding regulation, the EEA publishes its flagship report the State and Outlook of Europe's environment (SOER), which is an integrated assessment, analysing trends, progress to targets as well as outlook for the mid- to long-term. The agency publishes annually a report on Europe's most polluted provinces for air quality, detailing fine particulate matter PM 2.5.

The EEA shares this information, including the datasets used in its assessments, through its main website and a number of thematic information platforms such as Biodiversity Information System for Europe (BISE), Water Information System for Europe (WISE) and ClimateADAPT. The Climate-ADAPT knowledge platform presents information and data on expected climatic changes, the vulnerability of regions and sectors, adaptation case studies, and adaptation options, adaptation planning tools, and EU policy.

European Nature Information System
The European Nature Information System (EUNIS) provides access to the publicly available data in the EUNIS database for species, habitat types and protected sites across Europe. It is part of the European Biodiversity data centre (BDC), and is maintained by the EEA.

The database contains data
 * on species, habitat types and designated sites from the framework of Natura 2000,
 * from material compiled by the European Topic Centre on Biological Diversity
 * mentioned in relevant international conventions and in the IUCN Red Lists,
 * collected in the framework of the EEA's reporting activities.

European environment information and observation network
The European Environment Information and Observation Network (Eionet) is a collaboration network between EEA member countries and non-member, cooperating nations. Cooperation is facilitated through different national environmental agencies, ministries, or offices. Eionet encourages the sharing of data and highlights specific topics for discussion and cooperation among participating countries.

Eionet currently includes covers seven European Topic Centres (ETCs):
 * ETC on Biodiversity and Ecosystems (ETC BE)
 * ETC on Climate Change Adaptation and LULUCF (ETC CA)
 * ETC on Climate Change Mitigation (ETC CM)
 * ETC on Data Integration and Digitalisation (ETC DI)
 * ETC on Human Health and the Environment (ETC HE)
 * ETC on Circular Economy and Resource Use (ETC CE)
 * ETC on Sustainability Transitions (ETC ST)

The European Environment Agency (EEA) implements the "Shared Environmental Information System" principles and best practices via projects such as the "ENI SEIS II EAST PROJECT" & the "ENI SEIS II SOUTH PROJECT" to support environmental protection within the six eastern partnership countries (ENP) & to contribute to the reduction in marine pollution in the Mediterranean through the shared availability and access to relevant environmental information.

Budget management and discharge
As for every EU body and institution, the EEA's budget is subject to a discharge process, consisting of external examination of its budget execution and financial management, to ensure sound financial management of its budget. Since its establishment, the EEA has been granted discharge for its budget without exception. The EEA provides full access to its administrative and budgetary documents in its public documents register.

The discharge process for the 2010 budget required additional clarifications. In February 2012, the European Parliament's Committee on Budgetary Control published a draft report, identifying areas of concern in the use of funds and its influence for the 2010 budget such as a 26% budget increase from 2009 to 2010 to €50 600 000. and questioned that maximum competition and value-for-money principles were honored in hiring, also possible fictitious employees.

The EEA's Executive Director refuted allegations of irregularities in a public hearing. On 27 March 2012 Members of the European Parliament (MEPs) voted on the report and commended the cooperation between the Agency and NGOs working in the environmental area. On 23 October 2012, the European Parliament voted and granted the discharge to the European Environment Agency for its 2010 budget.

International cooperation
In addition to its 32 members and six Balkan cooperating countries, the EEA also cooperates and fosters partnerships with its neighbours and other countries and regions, mostly in the context of the European Neighbourhood Policy: Additionally the EEA cooperates with multiple international organizations and the corresponding agencies of the following countries:
 * Eastern Partnership member states: Belarus, Ukraine, Moldova, Armenia, Azerbaijan, Georgia
 * Union for the Mediterranean member states: Algeria, Egypt, Israel, Jordan, Lebanon, Libya, Morocco, Palestinian Authority, Syria, Tunisia
 * Other ENPI states: Russia
 * Central Asian states: Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, Uzbekistan
 * United States (Environmental Protection Agency)
 * Canada (Environment Canada)

Official languages
The 26 official languages used by the EEA are: Bulgarian, Czech, Croatian, Danish, German, Greek, English, Spanish, Estonian, Finnish, French, Hungarian, Icelandic, Italian, Lithuanian, Latvian, Malti, Dutch, Norwegian, Polish, Portuguese, Romanian, Slovak, Slovene, Swedish and Turkish.

title: European Environment Agency


text:
EV

Ev or EV may refer to:

Businesses

 * Electro-Voice, a United States manufacturer of amplifiers, microphones, other audio equipment and speakers
 * Expressjet Airlines (IATA designator)
 * Atlantic Southeast Airlines (IATA designator)
 * EV Direct, exclusive distributor of BYD in Australia

In economics

 * Embedded value, the present value of future profits for a life insurance company
 * Enterprise value, an economic measure reflecting the market value of a whole business
 * Equivalent variation, a measure of how much more money a consumer would pay before a price increase to avert the price increase

People

 * Ev (given name)

Science, technology, and mathematics

 * Electric vehicle, a vehicle using an electric motor instead of an internal combustion engine
 * Electric car, a type of electric vehicle
 * Electronvolt (eV), in physics, a unit of energy
 * Estradiol valerate, an estrogen medication
 * Evolution-Data Optimized, a telecommunications standard for the wireless transmission of data through radio signals
 * Expected value, the mean of a random variable's probability distribution
 * Exposure value, a combination of shutter speed and aperture in photography
 * Extended Validation Certificate, a type of X.509 Certificate used in securing computer communications
 * Extracellular vesicle, a membrane-bound vesicle
 * Stereo-4, also known as EV (Electro-Voice), a quadraphonic sound system developed in 1970
 * Exploration vessel (E/V), a type of marine vessel

Other uses

 * Land of Ev, a fictional country in the Oz books of L. Frank Baum and his successors
 * Eesti Vabariik, Estonian for Republic of Estonia
 * eingetragener Verein ('registered association'; e.V.), a legal status for a registered voluntary association in Germany and Austria
 * Enterprise Village, an educational program co-managed by the Stavros Institute in Pinellas County, Florida
 * Era vulgaris, pseudo-Latin for the Common Era
 * EuroVelo, a network of long-distance cycling routes in Europe

title: EV


text:
Erlang (programming language)

Erlang is a general-purpose, concurrent, functional high-level programming language, and a garbage-collected runtime system. The term Erlang is used interchangeably with Erlang/OTP, or Open Telecom Platform (OTP), which consists of the Erlang runtime system, several ready-to-use components (OTP) mainly written in Erlang, and a set of design principles for Erlang programs.

The Erlang runtime system is designed for systems with these traits:

 * Distributed
 * Fault-tolerant
 * Soft real-time
 * Highly available, non-stop applications
 * Hot swapping, where code can be changed without stopping a system.

The Erlang programming language has immutable data, pattern matching, and functional programming. The sequential subset of the Erlang language supports eager evaluation, single assignment, and dynamic typing.

A normal Erlang application is built out of hundreds of small Erlang processes.

It was originally proprietary software within Ericsson, developed by Joe Armstrong, Robert Virding, and Mike Williams in 1986, but was released as free and open-source software in 1998. Erlang/OTP is supported and maintained by the Open Telecom Platform (OTP) product unit at Ericsson.

History
The name Erlang, attributed to Bjarne Däcker, has been presumed by those working on the telephony switches (for whom the language was designed) to be a reference to Danish mathematician and engineer Agner Krarup Erlang and a syllabic abbreviation of "Ericsson Language". Erlang was designed with the aim of improving the development of telephony applications. The initial version of Erlang was implemented in Prolog and was influenced by the programming language PLEX used in earlier Ericsson exchanges. By 1988 Erlang had proven that it was suitable for prototyping telephone exchanges, but the Prolog interpreter was far too slow. One group within Ericsson estimated that it would need to be 40 times faster to be suitable for production use. In 1992, work began on the BEAM virtual machine (VM) which compiles Erlang to C using a mix of natively compiled code and threaded code to strike a balance between performance and disk space. According to co-inventor Joe Armstrong, the language went from lab product to real applications following the collapse of the next-generation AXE telephone exchange named AXE-N in 1995. As a result, Erlang was chosen for the next Asynchronous Transfer Mode (ATM) exchange AXD.

In February 1998, Ericsson Radio Systems banned the in-house use of Erlang for new products, citing a preference for non-proprietary languages. The ban caused Armstrong and others to make plans to leave Ericsson. In March 1998 Ericsson announced the AXD301 switch, containing over a million lines of Erlang and reported to achieve a high availability of nine "9"s. In December 1998, the implementation of Erlang was open-sourced and most of the Erlang team resigned to form a new company Bluetail AB. Ericsson eventually relaxed the ban and re-hired Armstrong in 2004.

In 2006, native symmetric multiprocessing support was added to the runtime system and VM.

Processes
Erlang applications are built of very lightweight Erlang processes in the Erlang runtime system. Erlang processes can be seen as "living" objects (object-oriented programming), with data encapsulation and message passing, but capable of changing behavior during runtime. The Erlang runtime system provides strict process isolation between Erlang processes (this includes data and garbage collection, separated individually by each Erlang process) and transparent communication between processes (see Location transparency) on different Erlang nodes (on different hosts).

Joe Armstrong, co-inventor of Erlang, summarized the principles of processes in his PhD thesis:

 * Everything is a process.
 * Processes are strongly isolated.
 * Process creation and destruction is a lightweight operation.
 * Message passing is the only way for processes to interact.
 * Processes have unique names.
 * If you know the name of a process you can send it a message.
 * Processes share no resources.
 * Error handling is non-local.
 * Processes do what they are supposed to do or fail.

Joe Armstrong remarked in an interview with Rackspace in 2013: "If Java is 'write once, run anywhere', then Erlang is 'write once, run forever'."

Usage
In 2014, Ericsson reported Erlang was being used in its support nodes, and in GPRS, 3G and LTE mobile networks worldwide and also by Nortel and T-Mobile.

Erlang is used in RabbitMQ. As Tim Bray, director of Web Technologies at Sun Microsystems, expressed in his keynote at O'Reilly Open Source Convention (OSCON) in July 2008: "If somebody came to me and wanted to pay me a lot of money to build a large scale message handling system that really had to be up all the time, could never afford to go down for years at a time, I would unhesitatingly choose Erlang to build it in."

Erlang is the programming language used to code WhatsApp.

It is also the language of choice for Ejabberd – an XMPP messaging server.

Elixir is a programming language that compiles into BEAM byte code (via Erlang Abstract Format).

Since being released as open source, Erlang has been spreading beyond telecoms, establishing itself in other vertical markets such as FinTech, gaming, healthcare, automotive, internet of things and blockchain. Apart from WhatsApp, there are other companies listed as Erlang's success stories: Vocalink (a MasterCard company), Goldman Sachs, Nintendo, AdRoll, Grindr, BT Mobile, Samsung, OpenX, and SITA.

Factorial
A factorial algorithm implemented in Erlang:

Fibonacci sequence
A tail recursive algorithm that produces the Fibonacci sequence:

Omitting the comments gives a much shorter program.

Quicksort
Quicksort in Erlang, using list comprehension:

The above example recursively invokes the function  until nothing remains to be sorted. The expression  is a list comprehension, meaning "Construct a list of elements   such that   is a member of , and   is less than  ." is the list concatenation operator.

A comparison function can be used for more complicated structures for the sake of readability.

The following code would sort lists according to length:

A  is taken from the first parameter given to   and the rest of   is named. Note that the expression

is no different in form from

(in the previous example) except for the use of a comparison function in the last part, saying "Construct a list of elements  such that   is a member of , and   is true", with   being defined earlier as

The anonymous function is named  in the parameter list of the second definition of   so that it can be referenced by that name within that function. It is not named in the first definition of, which deals with the base case of an empty list and thus has no need of this function, let alone a name for it.

Data types
Erlang has eight primitive data types:

 * Integers: Integers are written as sequences of decimal digits, for example, 12, 12375 and -23427 are integers. Integer arithmetic is exact and only limited by available memory on the machine. (This is called arbitrary-precision arithmetic.)
 * Atoms: Atoms are used within a program to denote distinguished values. They are written as strings of consecutive alphanumeric characters, the first character being lowercase. Atoms can contain any character if they are enclosed within single quotes and an escape convention exists which allows any character to be used within an atom. Atoms are never garbage collected and should be used with caution, especially if using dynamic atom generation.
 * Floats: Floating point numbers use the IEEE 754 64-bit representation.
 * References: References are globally unique symbols whose only property is that they can be compared for equality. They are created by evaluating the Erlang primitive.
 * Binaries: A binary is a sequence of bytes. Binaries provide a space-efficient way of storing binary data. Erlang primitives exist for composing and decomposing binaries and for efficient input/output of binaries.
 * Pids: Pid is short for process identifier – a Pid is created by the Erlang primitive  Pids are references to Erlang processes.
 * Ports: Ports are used to communicate with the external world. Ports are created with the built-in function . Messages can be sent to and received from ports, but these messages must obey the so-called "port protocol."
 * Funs: Funs are function closures. Funs are created by expressions of the form:.

And three compound data types:

 * Tuples: Tuples are containers for a fixed number of Erlang data types. The syntax  denotes a tuple whose arguments are   The arguments can be primitive data types or compound data types. Any element of a tuple can be accessed in constant time.
 * Lists: Lists are containers for a variable number of Erlang data types. The syntax  denotes a list whose first element is , and whose remaining elements are the list  . The syntax   denotes an empty list. The syntax   is short for  . The first element of a list can be accessed in constant time. The first element of a list is called the head of the list. The remainder of a list when its head has been removed is called the tail of the list.
 * Maps: Maps contain a variable number of key-value associations. The syntax is.

Two forms of syntactic sugar are provided:

 * Strings: Strings are written as doubly quoted lists of characters. This is syntactic sugar for a list of the integer Unicode code points for the characters in the string. Thus, for example, the string "cat" is shorthand for.
 * Records: Records provide a convenient way for associating a tag with each of the elements in a tuple. This allows one to refer to an element of a tuple by name and not by position. A pre-compiler takes the record definition and replaces it with the appropriate tuple reference.

Erlang has no method to define classes, although there are external libraries available.

"Let it crash" coding style
Erlang is designed with a mechanism that makes it easy for external processes to monitor for crashes (or hardware failures), rather than an in-process mechanism like exception handling used in many other programming languages. Crashes are reported like other messages, which is the only way processes can communicate with each other, and subprocesses can be spawned cheaply (see below). The "let it crash" philosophy prefers that a process be completely restarted rather than trying to recover from a serious failure. Though it still requires handling of errors, this philosophy results in less code devoted to defensive programming where error-handling code is highly contextual and specific.

Supervisor trees
A typical Erlang application is written in the form of a supervisor tree. This architecture is based on a hierarchy of processes in which the top level process is known as a "supervisor". The supervisor then spawns multiple child processes that act either as workers or more, lower level supervisors. Such hierarchies can exist to arbitrary depths and have proven to provide a highly scalable and fault-tolerant environment within which application functionality can be implemented.

Within a supervisor tree, all supervisor processes are responsible for managing the lifecycle of their child processes, and this includes handling situations in which those child processes crash. Any process can become a supervisor by first spawning a child process, then calling  on that process. If the monitored process then crashes, the supervisor will receive a message containing a tuple whose first member is the atom. The supervisor is responsible firstly for listening for such messages and secondly, for taking the appropriate action to correct the error condition.

Concurrency and distribution orientation
Erlang's main strength is support for concurrency. It has a small but powerful set of primitives to create processes and communicate among them. Erlang is conceptually similar to the language occam, though it recasts the ideas of communicating sequential processes (CSP) in a functional framework and uses asynchronous message passing. Processes are the primary means to structure an Erlang application. They are neither operating system processes nor threads, but lightweight processes that are scheduled by BEAM. Like operating system processes (but unlike operating system threads), they share no state with each other. The estimated minimal overhead for each is 300 words. Thus, many processes can be created without degrading performance. In 2005, a benchmark with 20 million processes was successfully performed with 64-bit Erlang on a machine with 16 GB random-access memory (RAM; total 800 bytes/process). Erlang has supported symmetric multiprocessing since release R11B of May 2006.

While threads need external library support in most languages, Erlang provides language-level features to create and manage processes with the goal of simplifying concurrent programming. Though all concurrency is explicit in Erlang, processes communicate using message passing instead of shared variables, which removes the need for explicit locks (a locking scheme is still used internally by the VM).

Inter-process communication works via a shared-nothing asynchronous message passing system: every process has a "mailbox", a queue of messages that have been sent by other processes and not yet consumed. A process uses the  primitive to retrieve messages that match desired patterns. A message-handling routine tests messages in turn against each pattern, until one of them matches. When the message is consumed and removed from the mailbox the process resumes execution. A message may comprise any Erlang structure, including primitives (integers, floats, characters, atoms), tuples, lists, and functions.

The code example below shows the built-in support for distributed processes:

As the example shows, processes may be created on remote nodes, and communication with them is transparent in the sense that communication with remote processes works exactly as communication with local processes.

Concurrency supports the primary method of error-handling in Erlang. When a process crashes, it neatly exits and sends a message to the controlling process which can then take action, such as starting a new process that takes over the old process's task.

Implementation
The official reference implementation of Erlang uses BEAM. BEAM is included in the official distribution of Erlang, called Erlang/OTP. BEAM executes bytecode which is converted to threaded code at load time. It also includes a native code compiler on most platforms, developed by the High Performance Erlang Project (HiPE) at Uppsala University. Since October 2001 the HiPE system is fully integrated in Ericsson's Open Source Erlang/OTP system. It also supports interpreting, directly from source code via abstract syntax tree, via script as of R11B-5 release of Erlang.

Hot code loading and modules
Erlang supports language-level Dynamic Software Updating. To implement this, code is loaded and managed as "module" units; the module is a compilation unit. The system can keep two versions of a module in memory at the same time, and processes can concurrently run code from each. The versions are referred to as the "new" and the "old" version. A process will not move into the new version until it makes an external call to its module.

An example of the mechanism of hot code loading:

For the second version, we add the possibility to reset the count to zero.

Only when receiving a message consisting of the atom  will the loop execute an external call to codeswitch/1 (  is a preprocessor macro for the current module). If there is a new version of the counter module in memory, then its codeswitch/1 function will be called. The practice of having a specific entry-point into a new version allows the programmer to transform state to what is needed in the newer version. In the example, the state is kept as an integer.

In practice, systems are built up using design principles from the Open Telecom Platform, which leads to more code upgradable designs. Successful hot code loading is exacting. Code must be written with care to make use of Erlang's facilities.

Distribution
In 1998, Ericsson released Erlang as free and open-source software to ensure its independence from a single vendor and to increase awareness of the language. Erlang, together with libraries and the real-time distributed database Mnesia, forms the OTP collection of libraries. Ericsson and a few other companies support Erlang commercially.

Since the open source release, Erlang has been used by several firms worldwide, including Nortel and T-Mobile. Although Erlang was designed to fill a niche and has remained an obscure language for most of its existence, its popularity is growing due to demand for concurrent services. Erlang has found some use in fielding massively multiplayer online role-playing game (MMORPG) servers.

title: Erlang (programming language)


text:
Euphoria (programming language)

Euphoria is a programming language created by Robert Craig of Rapid Deployment Software in Toronto, Ontario, Canada. Initially developed (though not publicly released) on the Atari ST, the first commercial release was for MS-DOS as proprietary software. In 2006, with the release of version 3, Euphoria became open-source software. The openEuphoria Group continues to administer and develop the project. In December 2010, the openEuphoria Group released version 4 of openEuphoria along with a new identity and mascot for the project. OpenEuphoria is currently available for Windows, Linux, macOS and three flavors of *BSD.

Euphoria is a general-purpose high-level imperative-procedural interpreted language. A translator generates C source code and the GNU compiler collection (GCC) and Open Watcom compilers are supported. Alternatively, Euphoria programs may be bound with the interpreter to create stand-alone executables. A number of graphical user interface (GUI) libraries are supported including Win32lib and wrappers for wxWidgets, GTK+ and IUP. Euphoria has a simple built-in database and wrappers for a variety of other databases.

Overview
The Euphoria language is a general purpose procedural language that focuses on simplicity, legibility, rapid development and performance via several means.
 * Simplicity – It uses just four built-in data types (see below) and implements automatic garbage collection.
 * Legibility – The syntax favors simple English keywords over the use of punctuation to delineate constructs.
 * Rapid development – An interpreter encourages prototyping and incremental development.
 * Performance – An efficient reference-counting garbage collector correctly handles cyclic references.

History
Developed as a personal project to invent a programming language from scratch, Euphoria was created by Robert Craig on an Atari Mega-ST. Many design ideas for the language came from Craig's Master's thesis in computer science at the University of Toronto. Craig's thesis was heavily influenced by the work of John Backus on functional programming (FP) languages.

Craig ported his original Atari implementation to the 16-bit DOS platform and Euphoria was first released, version 1.0, in July 1993 under a proprietary licence. The original Atari implementation is described by Craig as "primitive" and has not been publicly released. Euphoria continued to be developed and released by Craig via his company Rapid Deployment Software (RDS) and website rapideuphoria.com. In October 2006 RDS released version 3 of Euphoria and announced that henceforth Euphoria would be freely distributed under an open-source software licence.

RDS continued to develop Euphoria, culminating with the release of version 3.1.1 in August, 2007. Subsequently, RDS ceased unilateral development of Euphoria and the openEuphoria Group took over ongoing development. The openEuphoria Group released version 4 in December, 2010 along with a new logo and mascot for the openEuphoria project.

Version 3.1.1 remains an important milestone release, being the last version of Euphoria which supports the DOS platform.

Euphoria is an acronym for End-User Programming with Hierarchical Objects for Robust Interpreted Applications although there is some suspicion that this is a backronym.

The Euphoria interpreter was originally written in C. With the release of version 2.5 in November 2004 the Euphoria interpreter was split into two parts: a front-end parser, and a back-end interpreter. The front-end is now written in Euphoria (and used with the Euphoria-to-C translator and the Binder). The main back-end and run time library are written in C.

Features
Euphoria was conceived and developed with the following design goals and features:

 * Ease of learning and with consistent high-level constructs (more so than, for example, the BASIC language)
 * Implementation of flat-form 32-bit memory to avoid complex memory management and size-addressing limits
 * Debugging support and run-time error-handling
 * Subscript and type checking
 * Loose and strict variable typing
 * Programming via objects as types (user-defined or otherwise)
 * Interpreted, with automatic memory management and garbage collection
 * Heterogeneous collection types (sequences)
 * DOS graphics library (Euphoria language versions up to and including 3.1.1)
 * Debugger
 * Integrated database system
 * Low-level memory handling
 * Straightforward wrapping of (or access to) C libraries

Execution modes

 * Interpreter
 * C translator (E2C) for standalone executables or dynamic linking
 * Bytecode compiler and interpreter (shrouder )
 * The Binder binds the Euphoria source code to the interpreter to create an executable.
 * A read–eval–print loop (REPL) version is on the openEuphoria roadmap.

Use
Euphoria is designed to readily facilitate handling of dynamic sets of data of varying types and is particularly useful for string and image processing. Euphoria has been used in artificial intelligence experiments, the study of mathematics, for teaching programming, and to implement fonts involving thousands of characters. A large part of the Euphoria interpreter is written in Euphoria.

Data types
Euphoria has two basic data types:
 * Atom – A number, implemented as a 31-bit signed integer or a 64-bit IEEE floating-point. Euphoria dynamically changes between integer and floating point representation according to the current value.
 * Sequence – A vector (array) with zero or more elements. Each element may be an atom or another sequence. The number of elements in a sequence is not fixed (i.e., the size of the vector/array does not have to be declared). The program may add or remove elements as needed during run-time. Memory allocation-deallocation is automatically handled by reference counting. Individual elements are referenced using an index value enclosed in square brackets. The first element in a sequence has an index of one [1]. Elements inside embedded sequences are referenced by additional bracked index values, thus X[3][2] refers to the second element contained in the sequence that is the third element of X. Each element of a sequence is an object type (see below).

Euphoria has two additional data types predefined:
 * Integer – An atom, restricted to 31-bit signed integer values in the range $-1,073,741,824$ to $1,073,741,823$ ($-2^{30}$ to $2^{30}-1$). Integer data types are more efficient than the atom data types, but cannot contain the same range of values. Characters are stored as integers, e.g., coding ASCII-'A' is exactly the same as coding 65.
 * Object – A generic datatype which may contain any of the above (i.e., atom, sequence or integer) and which may be changed to another type during run-time.

There is no character string data type. Strings are represented by a sequence of integer values. However, because literal strings are so commonly used in programming, Euphoria interprets double-quote enclosed characters as a sequence of integers. Thus "ABC" is seen as if the coder had written: {'A', 'B', 'C'} which is the same as: {65, 66, 67}

Hello, World!
puts(1, "Hello, World!\n")

Examples
Program comments start with a double hyphen  and go through the end of line.

The following code looks for an old item in a group of items. If found, it removes it by concatenating all the elements before it with all the elements after it. Note that the first element in a sequence has the index one [1] and that $ refers to the length (i.e., total number of elements) of the sequence.

global function delete_item( object old, sequence group ) integer pos -- Code begins -- pos = find ( old, group ) if pos > 0 then group = group[1 .. pos-1] & group[pos+1 .. $]    end if     return group end function

The following modification to the above example replaces an old item with a new item. As the variables old and new have been defined as objects, they could be atoms or sequences. Type checking is not needed as the function will work with any sequence of data of any type and needs no external libraries.

global function replace_item( object old, object new, sequence group ) integer pos -- Code begins -- pos = find ( old, group ) if pos > 0 then group[pos] = new end if    return group end function

Furthermore, no pointers are involved and subscripts are automatically checked. Thus the function cannot access memory out-of-bounds. There is no need to allocate or deallocate memory explicitly and no chance of a memory leak.

The line

group = group[1 .. pos-1] & group[pos+1 .. $]

shows some of the sequence handling facilities. A sequence may contain a set of any types, and this can be sliced (to take a subset of the data in a sequence) and concatenated in expressions with no need for special functions.

Parameter passing
Arguments to routines are always passed by value; there is no pass-by-reference facility. However, parameters are allowed to be modified locally (i.e., within the callee) which is implemented very efficiently as sequences have automatic copy-on-write semantics. In other words, when you pass a sequence to a routine, initially only a reference to it is passed, but at the point the routine modifies this sequence parameter the sequence is copied and the routine updates only a copy of the original.

Comparable languages

 * Lua
 * Phix
 * Python
 * REBOL
 * Nim
 * Ruby

title: Euphoria (programming language)