The paradox.

A casino offers a game of chance for a single player in which a fair coin is tossed at each stage. The initial stake begins at 2 dollars and is doubled every time heads appears. The first time tails appears, the game ends and the player wins whatever is in the pot. Thus the player wins 2 dollars if tails appears on the first toss, 4 dollars if heads appears on the first toss and tails on the second, 8 dollars if heads appears on the first two tosses and tails on the third, and so on. Mathematically, the player wins 2 dollars, where "k" equals number of tosses (k must be a whole number and greater than zero). What would be a fair price to pay the casino for entering the game?  To answer this, one needs to consider what would be the average payout: with probability, the player wins 2 dollars; with probability the player wins 4 dollars; with probability the player wins 8 dollars, and so on. The expected value is thus  Assuming the game can continue as long as the coin toss results in heads and in particular that the casino has unlimited resources, this sum grows without bound and so the expected win for repeated play is an infinite amount of money. Considering nothing but the expected value of the net change in one's monetary wealth, one should therefore play the game at any price if offered the opportunity. Yet, in published descriptions of the game, many people expressed disbelief in the result. Martin Robert quotes Ian Hacking as saying "few of us would pay even $25 to enter such a game" and says most commentators would agree. The paradox is the discrepancy between what people seem willing to pay to enter the game and the infinite expected value.  In an empirical test of the problem, Georges-Louis Leclerc, Comte de Buffon found that in 2048 games, a total 10,057 dollars were paid, i.e. an average of less than 5 dollars per game.

Solutions.

Several approaches have been proposed for solving the paradox.

Expected utility theory.

The classical resolution of the paradox involved the explicit introduction of a utility function, an expected utility hypothesis, and the presumption of diminishing marginal utility of money.  In Daniel Bernoulli's own words: The determination of the value of an item must not be based on the price, but rather on the utility it yields.... There is no doubt that a gain of one thousand ducats is more significant to the pauper than to a rich man though both gain the same amount.  A common utility model, suggested by Bernoulli himself, is the logarithmic function "U"("w") = ln("w") (known as "log utility"). It is a function of the gambler's total wealth "w", and the concept of diminishing marginal utility of money is built into it. The expected utility hypothesis posits that a utility function exists the sign of whose expected net change from accepting the gamble is a good criterion for real people's behavior. For each possible event, the change in utility will be weighted by the probability of that event occurring. Let "c" be the cost charged to enter the game. The expected incremental utility of the lottery now converges to a finite value:  This formula gives an implicit relationship between the gambler's wealth and how much he should be willing to pay to play (specifically, any "c" that gives a positive change in expected utility). For example, with natural log utility, a millionaire ($1,000,000) should be willing to pay up to $20.88, a person with $1,000 should pay up to $10.95, a person with $2 should borrow $1.35 and pay up to $3.35.  Before Daniel Bernoulli published, in 1728, a mathematician from Geneva, Gabriel Cramer, had already found parts of this idea (also motivated by the St. Petersburg Paradox) in stating that the mathematicians estimate money in proportion to its quantity, and men of good sense in proportion to the usage that they may make of it.  He demonstrated in a letter to Nicolas Bernoulli that a square root function describing the diminishing marginal benefit of gains can resolve the problem. However, unlike Daniel Bernoulli, he did not consider the total wealth of a person, but only the gain by the lottery.  This solution by Cramer and Bernoulli, however, is not completely satisfying, since the lottery can easily be changed in a way such that the paradox reappears. To this aim, we just need to change the game so that it gives even more rapidly increasing payoffs. For any unbounded utility function, one can find a lottery that allows for a variant of the St. Petersburg paradox, as was first pointed out by Menger.  Recently, expected utility theory has been extended to arrive at more behavioral decision models. In some of these new theories, as in cumulative prospect theory, the St. Petersburg paradox again appears in certain cases, even when the utility function is concave, but not if it is bounded.

Probability weighting.

Nicolas Bernoulli himself proposed an alternative idea for solving the paradox. He conjectured that people will neglect unlikely events. Since in the St. Petersburg lottery only unlikely events yield the high prizes that lead to an infinite expected value, this could resolve the paradox. The idea of probability weighting resurfaced much later in the work on prospect theory by Daniel Kahneman and Amos Tversky.  Cumulative prospect theory is one popular generalization of expected utility theory that can predict many behavioral regularities. However, the overweighting of small probability events introduced in cumulative prospect theory may restore the St. Petersburg paradox. Cumulative prospect theory avoids the St. Petersburg paradox only when the power coefficient of the utility function is lower than the power coefficient of the probability weighting function. Intuitively, the utility function must not simply be concave, but it must be concave relative to the probability weighting function to avoid the St. Petersburg paradox. One can argue that the formulas for the prospect theory are obtained in the region of less than $400. This is not applicable for infinitely increasing sums in the St. Petersburg paradox.

Rejection of mathematical expectation.

Various authors, including Jean le Rond d'Alembert and John Maynard Keynes, have rejected maximization of expectation (even of utility) as a proper rule of conduct. Keynes, in particular, insisted that the "relative risk" of an alternative could be sufficiently high to reject it even if its expectation were enormous.

Finite St. Petersburg lotteries.

The classical St. Petersburg lottery assumes that the casino has infinite resources. This assumption is unrealistic, particularly in connection with the paradox, which involves the reactions of ordinary people to the lottery. Of course, the resources of an actual casino (or any other potential backer of the lottery) are finite. More importantly, the expected value of the lottery only grows logarithmically with the resources of the casino. As a result, the expected value of the lottery, even when played against a casino with the largest resources realistically conceivable, is quite modest. If the total resources (or total maximum jackpot) of the casino are "W" dollars, then "L" = floor(log("W")) is the maximum number of times the casino can play before it no longer fully covers the next bet. The expected value "E" of the lottery then becomes:  The following table shows the expected value "E" of the game with various potential bankers and their bankroll "W" (with the assumption that if you win more than the bankroll you will be paid what the bank has):  A rational person might not find the lottery worth even the modest amounts in the above table, suggesting that the naive decision model of the expected return causes essentially the same problems as for the infinite lottery. Even so, the possible discrepancy between theory and reality is far less dramatic.  The premise of infinite resources produces a variety of paradoxes in economics. In the martingale betting system, a gambler betting on a tossed coin doubles his bet after every loss, so that an eventual win would cover all losses; this system fails with any finite bankroll. The gambler's ruin concept shows a persistent gambler will go broke, even if the game provides a positive expected value, and no betting system can avoid this inevitability.

Recent discussions.

Although this paradox is three centuries old, new arguments are still being introduced.

Feller.

A mathematically correct solution involving sampling was offered by William Feller. In order to understand Feller's answer correctly, sufficient knowledge about probability theory and statistics is necessary, but it can be understood intuitively "to perform this game with a large number of people and calculate the expected value from the sample extraction". In this method, when the games of infinite number of times are possible, the expected value will be infinity, and in the case of finite, the expected value will be a much smaller value.

Samuelson.

Samuelson resolves the paradox by arguing that, even if an entity had infinite resources, the game would never be offered. If the lottery represents an infinite expected gain to the player, then it also represents an infinite expected loss to the host. No one could be observed paying to play the game because it would never be offered. As Paul Samuelson describes the argument: "Paul will never be willing to give as much as Peter will demand for such a contract; and hence the indicated activity will take place at the equilibrium level of zero intensity."

Further discussions.

Marginal utility and philosophical view.

The St. Petersburg paradox and the theory of marginal utility have been highly disputed in the past. For a discussion from the point of view of a philosopher, see.

Heuristic parameters and risks.

Recently some authors suggested using heuristic parameters (e.g. assessing the possible gains without neglecting the risks of the Saint Petersburg lottery) because of the highly stochastic context of this game. The expected output should therefore be assessed in the limited period where we can likely make our choices and, besides the non-ergodic features, considering some inappropriate consequences we could attribute to the expected value.

The St. Petersburg paradox or St. Petersburg lottery is a paradox related to probability and decision theory in economics. It is based on a particular (theoretical) lottery game that leads to a random variable with infinite expected value (i.e., infinite expected payoff) but nevertheless seems to be worth only a very small amount to the participants. The St. Petersburg paradox is a situation where a naive decision criterion which takes only the expected value into account predicts a course of action that presumably no actual person would be willing to take. Several resolutions are possible.

Petrohradský paradox přednesl roku 1738 Daniel Bernoulli před Petrohradskou akademií věd (předchůdce dnešní Ruské akademie věd). Jde o klasické pojednání o pravděpodobnosti, v němž rozebral následující paradox. Představme si hru, v níž se hází mincí, a to tak dlouho, dokud na ní nepadne „hlava“ („panna“), čímž hra končí. Výhra v této hře je závislá na pořadí posledního hodu, tedy toho, ve kterém poprvé padne hlava, a to tak, že pokud padne v prvním hodu, je výhra 1 dukát, padne-li v druhém, jsou to 2 dukáty, ve třetím 4, ve čtvrtém 8 atd. Výši výhry v této hře lze tedy zobecnit do vzorce formula_1, kde n je pořadí hodu, v němž padla hlava. Pravděpodobnost, že v každém jednom hodu mincí padne hlava, je 50%, tedy 0,5. Ale protože jde o sérii nezávislých náhodných pokusů, je pravděpodobnost konce hry právě po n-tém hodu rovna formula_2.


Preliminaries.

The Swedish phase of the Thirty Years War began when Gustavus Adolphus and his force of 13,000 landed at Peenemünde in 1630. Initially, Sweden's entrance into the war was considered a minor annoyance to the Catholic League and its allies; his only battles to this point had been inconclusive ones, or fought against generals of modest military ability.  Consequently, the Imperial Commander of the German Catholic League, Tilly, did not immediately respond to the arrival of the Swedes, being engaged in northern Italy. However, the effective end of the Mantuan War in 1631 ensured that the large Imperial army previously tied up there was now free to move into the German states.

Creating alliances.

When the Protestant princes showed little interest in attaching themselves to the Swedish cause, Gustavus opted for “rough wooing.” His troops moved south into Brandenburg, taking and sacking the towns of Küstrin and Frankfurt an der Oder. It was too late and too far to save one of Gustav's “occupied” allies, Magdeburg, from a horrific sack by Imperial troops, beginning on May 20, in which a major portion of the population was murdered and the city burned. The Swedes turned the sack of Magdeburg to good use: broadsides and pamphlets distributed throughout Europe ensured that prince and pauper alike understood how the Emperor, or at least his troops, treated his Protestant subjects.  Over the next few months, Gustavus consolidated his bridgehead and expanded across northern Germany, attracting support from German princes and building his army from mercenary forces along the way. By the time he reached the Saxon border, his force had grown to over 23,000 men.

Strategic importance of Saxony.

In order for Swedes to attack the Imperial troops in the south, they needed to pass through Saxony. In order for Tilly's forces to attack Gustav's army, they too needed to pass through Saxony. The Electorate of Saxony had not been affected by war and had large quantities of resources that each army could utilise. In midsummer, General Tilly asked John George I for permission to pass through the territory; the elector declined permission, noting that Saxony had not been ravaged by war yet. Later Tilly invaded the Electorate of Saxony due to the fact that it was the shortest distance between his army and Gustav's and it possibly annulled the chance of a potential alliance between Saxony and the Imperials.  His plan was to avoid contact with the Swedes, and ultimately the Saxons, until his troops could unite with the units near Jena (about 5,000 seasoned professionals), and the larger force of Count Otto von Fugger, "en route" from Hesse. Gustav and John George united their forces, planning to meet Tilly somewhere near Leipzig.

Tactical overview.

The battle was overall a meeting engagement with both combatants agreeing to battle on the field. The forces all had different structural organization. The level of technology was roughly equivalent, with newer, lighter cannon and matchlocks giving the Swedes a slight advantage. Both armies were well supplied, and the terrain gave neither a distinct advantage.

Forces deployed.

The forces deployed were roughly equal in strength with the Swedes being slightly outnumbered. The Protestant coalition fielded about 42,000 troops (18,000 of them German), and the Imperial army about 35,000. The Protestants had a considerable edge in cavalry numbers, about 13,000 (5,000 from Allies) to 9,000. Strength of heavy artillery was comparable, with the Swedes having a slight edge in quality and Imperial forces a marginal advantage in quantity. The Swedes had additional small artillery pieces (3 and 6 pounders) integrated into their infantry brigades and regiments, giving them a larger number of tubes overall and a huge firepower advantage in an infantry clash.  The Imperials had a considerable advantage in the number of trained infantry deployed, about 25,000 to the Swedes 15,000. The Saxons (Swedish allies) fielded about 9,000 untrained conscripts and militiamen, and had very few muskets. The Swedish brigade had more muskets and fewer pikemen than the Imperial tercios (who still retained large numbers of lighter firearms known as the arquebus or caliver); overall, the Protestants fielded about the same number of muskets as Imperial troops.

Force assessment.

The overall balance was relatively even. The disparity in overall numbers resulted from large levies of untrained soldiers. The number of heavy cannon was relatively close, with the Swedish having newer models and light cannon compensating for the disparity in heavy field pieces. The Swedes had a considerable advantage in cavalry numbers, although the Imperialist cavalry were better armored and better mounted. This balance would be tilted however by the Swedish practice of supporting their cavalry with detachment of musketeers.  Tilly also had a considerable numerical advantage in the number of veteran, trained infantry. Gustavus had a considerable advantage in his artillery arm; he had moved away from heavy siege artillery into more mobile field pieces, which because of its mobility and rate of fire were pound by pound much more effective than the latter. The Swedes also fielded considerably more powerful muskets by ratio, had far more advanced equipment, and better drills to increase their rate of fire. More important, the Linear Formation allowed most Swedish musketeers to fire at the same time, and allowed the Swedish infantry to match the Imperialist frontage with a smaller number of men, which would be crucial in the later phase of the battle. Finally, the Swedish aggressive assault method of firing by triple-ranked salvos at point blank range, compared to the Imperialist's more traditional way of firing by volley would prove to be a nasty shock to Tilly's tercios.

Disposition of forces.

The Swedes deployed their 15,000 infantry in brigades and two lines. The imperial army deployed 25,500 infantry in a single line of 17 tercios (1,500 infantrymen in each). The German allies extended the Swedish-Saxon front to be overall slightly longer than the Imperial. The imperial line had its cavalry evenly distributed on its flanks. The Swedes had their cavalry weighted to their right. The Saxon allies fielded their infantry in wedge formation with units in squares, and cavalry on their flanks. With their Saxon allies extending the Swedes' line, the Protestants had cavalry at the centre and their flanks.

Battle.

The battle started in the middle of the day and lasted over six hours. The first two hours consisted of an exchange of artillery fire. This was followed by an Imperial attack with cavalry from both wings to both ends of the Protestant line. The cavalry attack routed the Saxon troops on the Swedish left flank. The Imperial army then conducted a general attack to exploit the exposed left flank. The Swedes repositioned their second line to cover the left flank and counterattacked with their cavalry to both imperial flanks.  The attack on the Imperial left was led personally by Gustavus Adolphus, capturing the Imperial artillery and enveloping the Imperial left flank. The Swedes now had much greater weight of fire from their artillery, infantry, and the captured Imperial artillery. The Imperial line became disorganized under the heavy fire and was enveloped. The Imperial line collapsed and over 80% of Imperial forces were killed or captured.

Opening moves.

The combined Swedish-Saxon forces were to the north of Leipzig centred around hamlet of Podelwitz, facing southwest toward Breitenfeld and Leipzig. The battle began around mid-day, with a two-hour exchange of artillery fire, during which the Swedes demonstrated firepower in a rate of fire of three to five volleys to one Imperial volley. Gustavus had lightened his artillery park, and each colonel had four highly mobile, rapid firing, bronze-cast three pounders, the cream of Sweden's metallurgical industry. When the artillery fire ceased, Pappenheim's Black Cuirassiers charged without orders from Tilly, attempting to turn the Swedish right. Instead, their attack fell between Johan Banér's line and the Swedish reserves. They attacked six times to little effect; the small companies of musketeers dispersed between the squadrons of Swedish horse fired salvos at point blank range, disrupting the charge of the Imperialist cuirassier and allowing the Swedish cavalry to counterattack at an advantage. The same tactics worked an hour or so later when the Imperial cavalry charged the Swedish left flank. Following the rebuff of the seventh assault, General Banér sallied forth with both his light (Finnish and West Gaetlanders) and heavy cavalry (Smalanders and East Gaetlanders), forcing Pappenheim and his cavalry to quit the field in disarray, retreating 15 miles northwest to Halle.  During the charges of the Imperialist cuirassiers, Tilly's infantry had remained stationary, but then the cavalry on his right charged the Saxon cavalry and routed it towards Eilenburg. There may have been confusion in the Imperial command at seeing Pappenheim's charge; in their assessment of the battle, military historians have wondered if Pappenheim precipitated an attempted double envelopment, or if he followed Tilly's preconceived plan. At any rate, recognizing an opportunity, Tilly sent the majority of his infantry against the remaining Saxon forces in an oblique march diagonally across his front.

Thwarting the Imperial attack.

Tilly ordered his infantry to march ahead diagonally to the right, concentrating his forces on the weaker Saxon flank. The entire Saxon force was routed, leaving the Swedish left flank exposed. Before the Imperial forces could regroup and change face towards the Swedes, the commander of the Swedish Left, Marshal Gustav Horn, refused his line and counter-attacked before the tercios could regroup and change face.  The Imperialist tercios then faced the full brunt of the new Swedish firepower for the first time:  "...[Tilly] received a horrible, uninterrupted pounding from the king's light pieces and was prevented from coming to grips with the latter's forces." – Raimondo Montecuccoli, Imperial officer. "First (saith he), giving fire unto three little Field-pieces that I had before me, I suffered not my muskettiers to give their volleyes till I came within Pistollshot of the enemy, at which time I gave order to the first rancks to discharge at once, and after them the other three: which done we fell pell mell into their ranckes, knocking them downe with the stocke of the Musket and our swords." – Lt. Colonel Muschamp

Annihilation of the Imperial force.

With the Imperial forces engaged, the Swedish right and centre pivoted on the refused angle, bringing them in line with Horn. Banér's cavalry, under the direct command of Gustavus Adolphus, attacked across the former front to strike the Imperial left and capture their artillery. As Tilly's men came under fire from their own captured batteries, the Swedish cannon, under Lennart Torstensson, rotated, catching the tercios in a crossfire.  After several hours of punishment, nearing sunset, the Catholic line finally broke. Tilly and Pappenheim were both wounded, though they escaped. 7,600 Imperial soldiers were killed, and 6,000 were captured. The Saxon artillery was recaptured, along with all the Imperial guns and 120 regimental flags.

Aftermath.

The outcome of the battle had a significant impact in both the short and long terms.

Short-term effect.

In the short term, the Catholic and Imperial forces were significantly hampered by the loss of most of the force. One hundred and twenty standards of the Imperial and Bavarian armies were taken (and are still on display in the Riddarholm church in Stockholm). After the battle, Gustavus moved on Halle, following the same track that Tilly had taken coming east to enforce the Edict of Restitution on the Electorate of Saxony. Two days later Gustav's forces captured another 3,000 men after a brief skirmish at Merseburg, and took Halle two days after that.  After the battle, the Catholic League or Imperial army under Tilly could field an army of only 7,000 men. The army had to be rebuilt. Gustavus Adolphus, on the other hand, had a larger army after the battle than before. The battle's outcome had the political effect of convincing Protestant German states to join his cause. Finally, with the seventy-two-year-old Tilly's recovery far from certain (and he did indeed die within six months while crossing the Lech river), and with no alternative commander at hand, Emperor Ferdinand II had no choice but to rehire Wallenstein.

Long-term consequences.

The totality of the victory confirmed Gustav's military innovations and guaranteed that the Swedes would remain engaged in the war for the foreseeable future. In the long term, the significant loss of forces and the creation of a strong Protestant anti-Imperial force required the Emperor and the Protestant and Catholic princes to rethink on the operational conduct of the war, and the diplomatic avenues they would pursue with it.  Gustav's success encouraged several other princes to join the cause of the Swedish king and his few allies. By the month's end, Hanover, the Hessian dukes, Brandenburg and Saxony were officially aligned against the empire, and France had agreed to provide substantially greater funding for Gustavus' armies. Although Gustavus was killed a year later at the Battle of Lützen, the military strength of the alliance had been secured through the addition of new armies. Even when Swedish leadership faltered it did not fail, and the influx of French gold ensured that the hostilities could continue.

Battlefield today.

The battlefield today is bisected by the A14 autobahn, which slices through the fields where the majority of the action occurred, between the original position of Tilly, at Breitenfeld, and the original positions of the Swedes and Saxons, around Podelwitz.  In the eastern portion of the village of Breitenfeld stands a monument to Gustav Adolf and the victory his army accomplished there in 1631. It was erected in 1831 on the two hundredth anniversary of the battle and bears the following inscription:

The Battle of Breitenfeld (; ) or First Battle of Breitenfeld (in older texts sometimes known as Battle of Leipzig), was fought at a crossroads near Breitenfeld approximately 8 km north-west of the walled city of Leipzig on September 17 (Gregorian calendar), or September 7 (Julian calendar, in wide use at the time), 1631. It was the Protestants' first major victory of the Thirty Years War.

Bitva u Breitenfeldu se odehrála 17. září 1631 několik kilometrů severně od Lipska. Na jedné straně stála vojska Katolické ligy pod velením Jana Tserclaese Tillyho, na straně druhé vojska švédská, saská a německých protestantů pod velením švédského krále Gustava II. Adolfa. Bitva skončila drtivou porážkou vojsk Katolické ligy.


Plot.

Three months after the events of, Freddy Krueger, now powerless in Hell because the residents of Springwood have forgotten about him, uses what's left of his powers to bring Jason Voorhees back to life. Freddy then disguises himself as Jason's mother to manipulate Jason into killing Springwood teenagers to create fear and regain his strength.  Lori Campbell lives with her widowed father, and her friends Kia and Gibb, are sleeping over. They are later joined by Trey, Gibb's boyfriend, and his friend Blake, whom Kia tries to get Lori to hook up with, much to Lori's disgust. Jason kills Trey that night, and the police suspect Freddy. After a nightmare, Blake awakens to find his father killed before Jason kills him. The police call it a murder–suicide the following day, hoping to contain Freddy.  Lori's ex-boyfriend Will Rollins and his friend Mark Davis are patients at the Westin Hills Psychiatric Hospital, and take Hypnocil to suppress their dreams because of their previous contact with Freddy. A news report prompts them to escape and return to Springwood to tell Lori about Freddy. That night, Lori and the others attend a rave in a cornfield. Freddy tries to kill Gibb in a nightmare, but Jason kills her and several other attendees in the real world; this makes Freddy realize that Jason's rampage will deny him victims.  Linderman and Freeburg escape the rave with Will, Lori, and Kia. Lori and Will go to Mark's house, and find Freddy killing him. Deputy Stubbs approaches Lori and her friends, who realize Freddy's plan. Learning about the Hypnocil, they try to steal it from Westin Hills; Freddy possesses Freeburg, however, who disposes of the medicine. After electrocuting Stubbs, Jason is tranquilized by the possessed Freeburg and kills him before he falls asleep.  The teens devise a plan to pull Freddy from the dream world into reality and force him to fight Jason, bringing the unconscious Jason to the now-abandoned Camp Crystal Lake. Freddy fights Jason in the dream world, where his dream powers show him that Jason is afraid of water because of his death by drowning. He uses water to make Jason powerless, but Lori goes to sleep and tries to save Jason. Freddy attacks her and reveals himself as her mother's killer.  Jason awakens at Camp Crystal Lake and chases the teens into a cabin. Linderman is killed, and the cabin catches fire. Lori is awakened and pulls Freddy into the real world, where he is confronted by Jason. As Jason and Freddy fight, the remaining teens escape the cabin.  Kia distracts Freddy until Jason kills her. On a dock, the two killers do devestaing blows to each other, with Jason tearing Freddy's clawed arm off after Freddy cuts off Jason’s fingers and stabs his eyes. Lori and Will pour gasoline on the dock and set it afire; this makes propane tanks explode, throwing Freddy and Jason into the lake. Freddy climbs out and tries to kill Lori and Will, but is impaled by Jason with his own clawed arm; this allows Lori to decapitate Freddy as Jason falls, lifeless, into the lake. Lori and Will leave Camp Crystal Lake. A victorious Jason emerges from the water the next day, holding his machete and Freddy's severed head. When Jason walks out of the water, Freddy suddenly winks and his ominous laughter is heard in the background.

Cast.

Additionally, Evangeline Lilly had a walk-on role as a high-school student. Professional wrestler Óscar Gutiérrez, better known by his ring name Rey Mysterio, was Englund's stunt double for a scene in Freddy's boiler room lair. New Line Cinema studio chief Robert Shaye, who produced every preceding "Nightmare on Elm Street" film, played the school principal (credited as L.E. Moko).

Production.

Development.

Influenced by fan desire for a crossover film with a fight between Freddy and Jason, New Line and Paramount tried to make a "Freddy vs. Jason" movie in 1987 but could not agree on a story. When "" failed at the box office, Sean Cunningham wanted to reacquire the rights to "Friday the 13th" and begin working with New Line Cinema on "Freddy vs. Jason" (New Line owned "Nightmare on Elm Street"). Paramount and New Line wanted the license to the other's character so they could control a crossover film. Negotiations on the project collapsed, and Paramount made "Jason Takes Manhattan". After "" was released in 1989, the rights reverted to Scuderi, Minasian, and Barsamianto (who sold them to New Line). Before Cunningham could begin to work on "Freddy vs. Jason", Wes Craven returned to New Line to make "New Nightmare". This put "Freddy vs. Jason" on hold, but allowed Cunningham to bring Jason back with "". The ninth installment "turned a healthy profit". Cunningham's "frustration" with the delayed development of "Freddy vs. Jason" led him to create "Jason X" to keep the series alive. Based on "Jason Takes Manhattan"s concept of taking Jason away from Crystal Lake, the tenth film put the titular character in space. The film lost its biggest supporter with the resignation of president of production Michael De Luca. Lack of support let the finished film sit for two years before it was released on April 26, 2002. It was the series' lowest-grossing film at the domestic box office, and had the largest budget of any of the films to date. New Line spent a reported $6 million on script development alone from several different writers. Cyrus Voris & Ethan Reiff were commissioned by De Luca alongside Lewis Abernathy & Sean S. Cunningham. Neither draft was well liked by the studio so Brannon Braga & Ronald D. Moore were hired to bring the project in a new direction. David J. Schow was given an offer to write the script because he just happened to walk by De Luca's office one day. David S. Goyer and James Dale Robinson both subsequently rewrote the Voris/Reiff draft. Rob Bottin, known for his make-up work on "The Thing" and "Total Recall", was selected to direct the film in 1997. Mark Verheiden entered the project in the late '90s and proposed releasing the film with two different endings; one with Freddy winning and one with Jason winning. Screenwriting duo Jonathan Aibel & Glenn Berger, and later Peter Briggs, were also brought in to write for the film. Newcomers Mark Swift & Damian Shannon were hired after delivering a pitch that De Luca was happy with. Goyer returned to the project once again in an effort to trim "every ounce of fat" from Swift & Shannon's 120 page script. According to Swift and Shannon, several endings were considered for the film; one involved Pinhead of the "Hellraiser" franchise, but New Line did not want to secure the rights for the character.

Casting Jason.

New Line, thinking that "Freddy vs. Jason" needed a fresh start, chose a different actor to play Jason. Cunningham disagreed with their decision, believing that Kane Hodder was the best choice for the role. Although Hodder received a script for "Freddy vs. Jason" and met with director Ronny Yu and New Line executives, Yu and Matthew Barry felt that the role should be recast to fit Yu's image of Jason. Hodder said that New Line did not give him a reason for the recasting; according to Yu, however, he wanted a slower and more-deliberate Jason. The role went to Ken Kirzinger, a Canadian stuntman who worked on "Jason Takes Manhattan". Yu said that Kirzinger was hired because he was taller than Robert Englund, who played Freddy Krueger. Kirzinger is tall, compared to the Hodder, and Yu wanted a much taller actor than the Englund. Kirzinger believed that his experience on "Part VIII" (doubling for Hodder in two scenes) and his height helped him land the part. New Line did not cast Kirzinger until it saw him on film, and his first scene was Jason walking down Elm Street. Douglas Tait played Jason in a re-shot ending:

Distribution.

Novelization.

Black Flame published a novelization of the film on July 29, 2003.

Home media.

The film was released on VHS and DVD as part of New Line's Platinum Series on January 13, 2004. The DVD release contained a second disc of bonus content with audio commentary by Ronny Yu, Ken Kirzinger and Robert Englund; deleted and alternate scenes with commentary; Ill Niño's music video for "How Can I Live"; trailers and TV ads, soundtrack promotion and behind-the-scenes featurettes. The film was released on October 4, 2005 on Universal Media Disc and September 8, 2009 on Blu-ray; the Blu-ray release had the same content as the Platinum Series DVD.

Reception.

Critical response.

On Rotten Tomatoes, the film has an approval rating of 41% based on 160 reviews and an average rating of 4.85/10. The website's critical consensus reads, "Fans of the two horror franchises will enjoy this showdown. But for everyone else, it's the same old slice and dice." On Metacritic the film has a weighted average score of 37 out of 100 based on 29 reviews, indicating "generally unfavorable reviews". Audiences polled by CinemaScore gave it an average grade of B+ on an A+-to-F scale.

Accolades.

Doug Chapman and Glenn Ennis were nominated for the Best Fire Stunt award at the Taurus World Stunt Awards 2004 for the double full-body burn and wire stunt. Chapman doubled for Robert Englund as Freddy and Ennis doubled for Ken Kirzinger as Jason in the stunt. The film was also nominated for Best Horror Film at the Saturn Awards.

Freddy vs. Jason is a 2003 American slasher action film directed by Ronny Yu and written by Damian Shannon and Mark Swift. The film, a crossover between the "A Nightmare on Elm Street" and "Friday the 13th" series, retroactively establishes them in a shared universe and pits Freddy Krueger and Jason Voorhees against each other. It is the last film in each series before their respective reboots. The film is the eighth in the "A Nightmare on Elm Street" franchise and the eleventh in the "Friday the 13th" franchise.

Freddy vs. Jason je americký hororový film, ve kterém se proti sobě střetávají dvě slavné hororové postavy z 80. let, popálený Freddy Krueger z " Noční můry v Elm Street" a Jason Voorhees z "Pátku třináctého".


Early life and education.

Daubechies was born in Houthalen, Belgium, as the daughter of Marcel Daubechies (a civil mining engineer) and Simonne Duran (then a homemaker, later a criminologist). She remembers that when she was a little girl and could not sleep, she did not count numbers, as you would expect from a child, but started to multiply numbers by two from memory. Thus, as a child, she already familiarized herself with the properties of exponential growth. Her parents found out that mathematical conceptions, like cone and tetrahedron, were familiar to her before she reached the age of 6. She excelled at the primary school, moved up a class after only 3 months. After completing the Lyceum in Hasselt she entered the Vrije Universiteit Brussel at 17.  Daubechies completed her undergraduate studies in physics at the Vrije Universiteit Brussel in 1975. During the next few years, she visited the CNRS Center for Theoretical Physics in Marseille several times, where she collaborated with Alex Grossmann; this work was the basis for her doctorate in quantum mechanics. She obtained her Ph.D. in theoretical physics in 1980 at Free University in Brussels.

Career.

Daubechies continued her research career at the Vrije Universiteit Brussel until 1987, rising through the ranks to positions roughly equivalent with research assistant-professor in 1981 and research associate-professor 1985, funded by a fellowship from the NFWO (Nationaal Fonds voor Wetenschappelijk Onderzoek).  Daubechies spent most of 1986 as a guest-researcher at the Courant Institute of Mathematical Sciences. At Courant she made her best-known discovery: based on quadrature mirror filter-technology she constructed compactly supported continuous wavelets that would require only a finite amount of processing, in this way enabling wavelet theory to enter the realm of digital signal processing.  In July 1987, Daubechies joined the Murray Hill AT&T Bell Laboratories' New Jersey facility. In 1988 she published the result of her research on orthonormal bases of compactly supported wavelets in Communications on Pure and Applied Mathematics. From 1991-1994 Daubechies taught as a professor at Rutgers University in their Mathematics Department.  In 1994, Daubechies moved to Princeton University, where she was active within the Program in Applied and Computational Mathematics. In 2004 she was named William R. Kenan, Jr. Professor and became the first female full professor of mathematics at Princeton. In January 2011 Daubechies moved to Duke University to serve as the James B. Duke Professor in the department of mathematics and electrical and computer engineering at Duke University. In 2016, she and Heekyoung Hahn founded Duke Summer Workshop in Mathematics (SWIM) for female rising high school seniors.  Daubechies is on the board of directors of Enhancing Diversity in Graduate Education (EDGE), a program that helps women entering graduate studies in the mathematical sciences. She was the first woman to be president of the International Mathematical Union (2011–2014).

Awards and honors.

Daubechies received the Louis Empain Prize for Physics in 1984, awarded once every five years to a Belgian scientist on the basis of work done before the age of 29. Between 1992 and 1997 she was a fellow of the MacArthur Foundation and in 1993 was elected to the American Academy of Arts and Sciences. In 1994 she received the American Mathematical Society Steele Prize for Exposition for her book "Ten Lectures on Wavelets" and was invited to give a plenary lecture at the International Congress of Mathematicians in Zurich. In 1997 she was awarded the AMS Ruth Lyttle Satter prize. In 1998, she was elected to the United States National Academy of Sciences and won the Golden Jubilee Award for Technological Innovation from the IEEE Information Theory Society She became a foreign member of the Royal Netherlands Academy of Arts and Sciences in 1999.  In 2000, Daubechies became the first woman to receive the National Academy of Sciences Award in Mathematics, presented every 4 years for excellence in published mathematical research. The award honored her "for fundamental discoveries on wavelets and wavelet expansions and for her role in making wavelets methods a practical basic tool of applied mathematics". She was awarded the Basic Research Award, German Eduard Rhein Foundation and the NAS Award in Mathematics.  In January 2005, Daubechies became the third woman since 1924 to give the Josiah Willard Gibbs Lecture sponsored by the American Mathematical Society. Her talk was on "The Interplay Between Analysis and Algorithm".  Daubechies was the 2006 Emmy Noether Lecturer at the San Antonio Joint Mathematics Meetings. In September 2006, the Pioneer Prize from the International Council for Industrial and Applied Mathematics was awarded jointly to Daubechies and Heinz Engl.  In 2010 she was awarded an honorary doctorate by The Norwegian University of Science and Technology (NTNU).  In 2011, Daubechies was the SIAM John von Neumann Lecturer, and was awarded the IEEE Jack S. Kilby Signal Processing Medal, the Leroy P. Steele Prize for Seminal Contribution to Research from the American Mathematical Society, and the Benjamin Franklin Medal in Electrical Engineering from the Franklin Institute.  In 2012, King Albert II of Belgium granted Daubechies the title of Baroness. She also won the 2012 Nemmers Prize in Mathematics, Northwestern University, and the 2012 BBVA Foundation Frontiers of Knowledge Award in the Basic Sciences category (jointly with David Mumford).  In 2015, Daubechies gave the Gauss Lecture of the German Mathematical Society. The Simons Foundation, a private foundation based in New York City that funds research in mathematics and the basic sciences, gave Daubechies the Math + X Investigator award, which provides money to professors at American and Canadian universities to encourage new partnerships between mathematicians and researchers other fields of science. She was the one to suggest Simons that the foundation should fund not new research but better mechanisms for interpreting existing data.  In 2018, Daubechies won the William Benter Prize in Applied Mathematics from City University of Hong Kong (CityU). She is the first female recipient of the award. Prize officials cited Professor Daubechies' pioneering work in wavelet theory and her "exceptional contributions to a wide spectrum of scientific and mathematical subjects...her work in enabling the mobile smartphone revolution is truly symbolic of the era."  In 2018, Daubechies was awarded the Fudan-Zhongzhi Science Award ($440,000) for her work on wavelets. She is part of the 2019 class of fellows of the Association for Women in Mathematics.  Daubechies was named the North American Laureate of 2019 L'Oréal-UNESCO International Award For Women in Science. Since 1998, the award annually recognizes five outstanding women in chemistry, physics, materials science, mathematics, and computer science worldwide; Daubechies was chosen (for North America) along with Najat Aoun Saliba (Africa and Arab States), Maki Kawai (Asia Pacific), Karen Hallberg (Latin America), and Claire Voisin (Europe).

Personal life.

In 1985, Daubechies met mathematician Robert Calderbank, then on a 3-month exchange visit from AT&T Bell Laboratories, New Jersey to the Brussels-based mathematics division of Philips Research; they married in 1987. They have two children, Michael and Carolyn Calderbank.

Ingrid Daubechies ( ; ; born 17 August 1954) is a Belgian physicist and mathematician. She is best known for her work with wavelets in image compression.

Ingrid Daubechies (* 17. srpna 1954 Houthalen, Belgie) je původem belgická fyzička a matematička a v současné době profesorka na Princetonské univerzitě v USA.


History.

FN Herstal originated in the small city of Herstal, near Liège. The "Fabrique Nationale d'Armes de Guerre" (French for "National Factory of Weapons of War") was established in 1889 to manufacture 150,000 Mauser Model 89 rifles ordered by the Belgian Government. FN was co-founded by the major arms makers of the Liège region, with Henri Pieper of Anciens Etablissements Pieper being the driving force and the primary shareholder of the new company. In 1897, the company entered into a long-lasting relationship with John Moses Browning, a well-known American firearms designer. FN was an important manufacturer of motor vehicles in Belgium, a development championed by Alexandre Galopin as managing director. Cars were produced in Herstal in the early 1900s until 1935. Production of FN motorcycles continued until 1965, and production of trucks until 1970. In 1973, FN changed its name to reflect a product line diversified far beyond just "weapons of war", adopting the current name of "Fabrique Nationale d'Herstal".  One of Fabrique Nationale's handguns, a Model 1910 semi-automatic pistol in 9×17mm (.380 ACP) (serial number 19074) was one of four weapons that were taken from the assassins of Archduke Franz Ferdinand of Austria, although it is unknown which of the four weapons fired the fatal round.  Browning began development of the GP35 "High Power" pistol, the GP standing for "Grande Puissance" (French for "high power"), which is well-known as the Browning Hi-Power. The weapon was finalized by FN's Dieudonné Saive and did not appear until 1935, nearly a decade after Browning's death; it remained in production until 2017.  The FN Manufacturing LLC plant in Columbia, South Carolina, is part of the military division of FN. It is primarily responsible for the production of U.S. military weapons, such as M16 rifles, M249 light machine guns, M240 machine guns, and M2 machine guns.

Fabrique Nationale Herstal (), self-identified as FN Herstal and often referred to as Fabrique Nationale or simply FN, is a leading firearms manufacturer located in Herstal, Belgium, owned by the holding company Herstal Group which is in turn owned by the regional government of Wallonia. It is currently the largest exporter of military small arms in Europe.

Fabrique Nationale de Herstal nebo FN Herstal (někdy zkracováno jen na Fabrique Nationale (FN) je belgická firma vyrábějící ruční palné zbraně a kulomety. Se značkou FN se setkáme pouze u zbraní pro ozbrojené složky, pro civilní produkci firma používá obchodní značku Browning.


History.

The concept of virtual worlds significantly predates computers. The Roman naturalist, Pliny the Elder, expressed an interest in perceptual illusion. In the twentieth century, the cinematographer Morton Heilig explored the creation of the Sensorama, a theatre experience designed to stimulate the senses of the audience—vision, sound, balance, smell, even touch (via wind)—and so draw them more effectively into the productions  Among the earliest virtual worlds implemented by computers were virtual reality simulators, such as the work of Ivan Sutherland. Such devices are characterized by bulky headsets and other types of sensory input simulation. Contemporary virtual worlds, in particular the multi-user online environments, emerged mostly independently of this research, fueled instead by the gaming industry but drawing on similar inspiration. While classic sensory-imitating virtual reality relies on tricking the perceptual system into experiencing an immersive environment, virtual worlds typically rely on mentally and emotionally engaging content which gives rise to an immersive experience.  Maze War was the first networked, 3D multi-user first person shooter game. Maze introduced the concept of online players in 1973–1974 as "eyeball 'avatars' chasing each other around in a maze." It was played on ARPANET, or Advanced Research Projects Agency Network, a precursor to the Internet funded by the United States Department of Defense for use in university and research laboratories. The initial game could only be played on an Imlac, as

Virtual world concepts.

Definitions for a "virtual world" include:  There is no generally accepted definition of virtual world, but they do require that the world be persistent; in other words, the world must continue to exist even after a user exits the world, and user-made changes to the world should be preserved. While the interaction with other participants is done in real-time, time consistency is not always maintained in online virtual worlds. For example, "EverQuest" time passes faster than real-time despite using the same calendar and time units to present game time.  As "virtual world" is a general term, the virtual environment supports varying degrees of play and gaming. Some uses of the term include

Economy.

A virtual economy is the emergent property of the interaction between participants in a virtual world. While the designers have a great deal of control over the economy by the encoded mechanics of trade, it is nonetheless the actions of players that define the economic conditions of a virtual world. The economy arises as a result of the choices that players make under the scarcity of real and virtual resources such as time or currency. Participants have a limited time in the virtual world, as in the real world, which they must divide between task such as collecting resources, practicing trade skills, or engaging in less productive fun play. The choices they make in their interaction with the virtual world, along with the mechanics of trade and wealth acquisition, dictate the relative values of items in the economy. The economy in virtual worlds is typically driven by in-game needs such as equipment, food, or trade goods. Virtual economies like that of Second Life, however, are almost entirely player-produced with very little link to in-game needs. While the relevance of virtual world economics to physical world economics has been questioned, it has

Geography.

The geography of virtual worlds can vary widely because the role of geography and space is an important design component over which the developers of virtual worlds have control and may choose to alter. Virtual worlds are, at least superficially, digital instantiations of three-dimensional space. As a result, considerations of geography in virtual worlds (such as World of Warcraft) often revolve around “spatial narratives” in which players act out a nomadic hero's journey along the lines of that present in "The Odyssey". The creation

Research.

Virtual spaces can serve a variety of research and educational goals and may be useful for examining human behaviour. Offline- and virtual-world personalities differ from each other but are nevertheless significantly related which has a number of implications for self-verification, self-enhancement and other personality theories. Panic and agoraphobia have also been studied in a virtual world.  Given the large engagement, especially of young children in virtual worlds, there has been a steady growth in research studies involving the social, educational and even emotional impact of virtual worlds on children. The John D. and Catherine T. MacArthur Foundation for example have funded research into virtual worlds including, for example, how preteens explore and share information about reproductive health. A larger set of studies on

Hardware.

Unlike most video games, which are usually navigated using various free-ranging human interface devices (HIDs), virtual worlds are usually navigated (as of 2009) using HIDs which are designed and oriented around flat, 2-dimensional graphical user interfaces; as most comparatively inexpensive computer mice are manufactured and distributed for 2-dimensional UI navigation, the lack of 3D-capable HID usage among most virtual world users is likely due to both the lack of penetration of 3D-capable devices into non-niche, non-gaming markets as well as the generally higher pricing of such devices compared to 2-dimensional HIDs. Even those

Application domains.

Social.

Although the social interactions of participants in virtual worlds are often viewed in the context of 3D Games, other forms of interaction are common as well, including forums, blogs, wikis, chatrooms, instant messaging, and video-conferences. Communities are born in places which have their own rules, topics, jokes, and even language. Members of

Medical.

Disabled or chronically invalided people of any age can benefit enormously from experiencing the mental and emotional freedom gained by temporarily leaving their disabilities behind and doing, through the medium of their avatars, things as simple and potentially accessible to able, healthy people as walking, running, dancing, sailing, fishing, swimming, surfing, flying, skiing, gardening, exploring and other physical activities which their illnesses or disabilities prevent them from doing in real life. They may also be able to socialize, form friendships and relationships much more easily and avoid the stigma and other obstacles which would normally be attached to their disabilities. This can be much more constructive, emotionally satisfying and mentally fulfilling than passive pastimes such as television watching, playing computer games, reading or more conventional types of internet use.  The Starlight Children's Foundation helps hospitalized children (suffering from painful diseases or autism for example) to create a comfortable and safe environment which can expand their situation, experience interactions (when the involvement of a multiple cultures and players from around the world is factored in) they may not have been able to experience without a virtual world, healthy or sick. Virtual worlds also enable them to experience and act beyond the restrictions of their illness and help to relieve stress.  Virtual worlds can help players become more familiar and comfortable with actions they may in real-life feel reluctant or embarrassed. For example, in World of Warcraft, /dance is the emote for a dance move which a player in the virtual world can "emote" quite simply. And a familiarization with said or similar "emotes" or social skills (such as, encouragement, gratitude, problem-solving, and even kissing) in the virtual world via avatar can make the assimilation to similar forms of expression, socialization, interaction in real life smooth. Interaction with humans through avatars in the virtual world has potential to seriously expand the mechanics of one's interaction with real-life interactions.  Commercial

Entertainment.

There are many MMORPG virtual worlds out on many platforms. Most notable are IMVU for Windows, PlayStation Home for PlayStation 3, and Second Life for Windows. Many Virtual worlds have shut down since launch however. Notable shutdowns are The Sims Online, The Sims Bustin Out Online Weekend Mode, PlayStation Home, and Club Penguin.

Single-player games.

Some single-player video games contain virtual worlds populated by non-player characters (NPC). Many of these allow players to save the current state of this world instance to allow stopping and restarting the virtual world at a later date. (This can be done with some multiplayer environments as well.)  The virtual worlds found in video games are often split into discrete levels.  Single-player games such as "Minecraft" allow players to optionally create their own world without other players, and then combine skills from the game to work together with other players and create bigger and more intricate environments. These environments can then be accessed by other players, if the server is available to other players then they may be able to modify parts of it, such as the structure of the environment.  At one level, a more or less realistic rendered 3D space like the game world of "Halo 3" or "Grand Theft Auto V" is just as much a big database as Microsoft's Encarta encyclopedia.

Use in education.

Virtual worlds represent a powerful new medium for instruction and education that presents many opportunities but also some challenges. Persistence allows for continuing and growing social interactions, which themselves can serve as a basis for collaborative education. The use of virtual worlds can give teachers the opportunity to have a greater level of student participation. It allows users to be able to carry out tasks that could be difficult in the real world due to constraints and restrictions, such as cost, scheduling or location. Virtual worlds have the capability to adapt and grow to different user needs, for example, classroom teachers are able to use virtual worlds in their classroom leveraging their interactive whiteboard with the open-source project Edusim. They can be a good source of user feedback, the typical paper-based resources have limitations that Virtual Worlds can overcome.  Multi-user virtual worlds with easy-to-use affordances for building are useful in project-based learning. For example, Active Worlds is used to support classroom teachers in Virginia Beach City Public Schools, the out-of-school NASA RealWorld-InWorld Engineering Design Challenge, and many after school and in school programs in EDUni-NY. Projects range from tightly scaffolded reflection spaces to open building based on student-centered designs. New York Museums AMNH and NYSci have used the medium to support STEM learning experiences for their program participants.  Virtual worlds can also be used with virtual learning environments, as in the case of what is done in the Sloodle project, which aims to merge Second Life with Moodle.  Virtual worlds allow users with specific needs and requirements to access and use the same learning materials from home as they would receive if they were physically present. Virtual worlds can help users stay up to date with relevant information and needs while also feeling as they are involved. Having the option to be able to attend a presentation via a virtual world from home or from their workplace, can help the user to be more at ease and comfortable. Although virtual worlds are used as an alternative method of communicating and interacting with students and teachers, a sense of isolation can occur such as losing certain body language cues and other more personal aspects that one would achieve if they were face to face.  Some virtual worlds also offer an environment where simulation-based activities and games allow users to experiment various phenomenon and learn the underlying physics and principles. An example is Whyville launched in 1999, which targets kids and teenagers, offering them many opportunities to experiment, understand and learn. Topics covered in Whyville vary from physics to nutrition to ecology. Whyville also has a strong entrepreneurial structure based on user created virtual content sold in the internal virtual economy.  Some multi-user virtual worlds have become used for educational purposes and are thus called Multi-User Virtual Learning Environments (MUVLEs). Examples have included the use of Second Life for teaching English as a foreign languages (EFL) Many specialist types of MUVLE have particular pedagogies associated with them. For instance, George Siemens, Stephen Downes continue to promote the use of a type of MUVLE Dave Cormier coined called a 'MOOC'. Even though MOOCs were once seen as "next big thing" by universities and online education service providers such as Blackboard Inc, this was in fact what has been called a "stampede." By early 2013, serious questions emerged about whether MOOCs were simply part of a hype cycle and indeed following that hype whether academia was thus "MOOC'd out."

In fiction.

Virtual worlds, virtual reality, and cyberspace are popular fictional motifs. The first was probably John M. Ford's 1980 novel "Web of Angels", and a prominent early example is the work of William Gibson. Virtual worlds are integral to works such as "Tron", "Neuromancer", "Ghost in the Shell", "Snow Crash", "The Lawnmower Man", "", "ReBoot", "Digimon", "The Matrix", "MegaMan NT Warrior", "Epic", "Code Lyoko" and "Real Drive".  In A.K. Dewdney's novel, "the Planiverse" (1984), college students create a virtual world called 2DWorld, leading to contact with Arde, a two-dimensional parallel universe.  The main focus of the cyberpunk, psychological, 13-episode anime titled "Serial Experiments Lain" is the Wired, a virtual reality world that governs the sum of all electronic communication and machines; outer receptors are used to mentally transport a person "into"

Future.

Virtual worlds may lead to a "mobility" of labor that may impact national and organizational competitiveness in a manner similar to the changes seen with the mobility of goods and then the mobility of labor.  Virtual worlds may increasingly function as centers of commerce, trade, and business. Virtual asset trade is massive and growing; e.g., Second Life revenue reached approximately 7 million US Dollars per month, in 2011. Real world firms, such as Coca-Cola, have used virtual worlds to advertise their brand.

A virtual world is a computer-simulated environment which may be populated by many users who can create a personal avatar, and simultaneously and independently explore the virtual world, participate in its activities and communicate with others. These avatars can be textual, two or

Virtuální svět je druh online komunity, která má často formu počítačově simulovaného prostředí, pomocí kterého můžou uživatelé vzájemně interagovat, vytvářet a užívat objekty. Tento termín se dnes stává synonymem interaktivních 3D virtuálních prostředí, kde uživatelé nabírají formu avatárů viditelnou pro ostatní uživatele. Tyto avatáry jsou obyčejně znázorněny jako textový, dvou dimenzionálním, tří dimenzionální grafické reprezentace nebo můžou mít i jiné formy. (například zvukové nebo dotykové). Některé virtuální světy povolují mnohonásobné uživatele.


Systematics and taxonomy.

The taxonomy of the finch family, in particular the cardueline finches, has a long and complicated history. The study of the relationship between the taxa has been confounded by the recurrence of similar morphologies due to the convergence of species occupying similar niches. In 1968 the American ornithologist Raymond Andrew Paynter Jr. wrote:  Limits of the genera and relationships among the species are less understood – and subject to more controversy – in the carduelines than in any other species of passerines, with the possible exception of the estrildines [waxbills].  Beginning in around 1990 a series of phylogenetic studies based on mitochondrial and nuclear DNA sequences resulted in substantial revisions being made to the taxonomy. Several groups of birds that had previously been assigned to other families were found to be related to the finches. The Neotropical "Euphonia" and the "Chlorophonia" were formerly placed in the tanager family Thraupidae due to their similar appearance but analysis of mitochondrial DNA sequences revealed that both genera were more closely related to the finches. They are now placed in a separate subfamily Euphoniinae within the Fringillidae. The Hawaiian honeycreepers were at one time placed in their own family, Drepanididae but were found to be closely related to the "Carpodacus" rosefinches and are now placed within the Carduelinae subfamily. The three largest genera, "Carpodacus", "Carduelis" and "Serinus" were found to be polyphyletic. Each was split into monophyletic genera. The American rosefinches were moved from "Carpodacus" to "Haemorhous". "Carduelis" was split by moving the greenfinches to "Chloris" and a large clade into "Spinus" leaving just three species in the original genus. Thirty seven species were moved from "Serinus" to "Crithagra" leaving eight species in the original genus. Today the family Fringillidae is divided into three subfamilies, the Fringillinae containing a single genus with the chaffinches, the Carduelinae containing 183 species divided into 49 genera, and the Euphoniinae containing the "Euphonia" and the "Chlorophonia". Although Przewalski's "rosefinch" ("Urocynchramus pylzowi") has ten primary flight feathers rather than the nine primaries of other finches, it was sometimes classified in the Carduelinae. It is now assigned to a distinct family, Urocynchramidae, monotypic as to genus and species, and with no particularly close relatives among the Passeroidea.

Fossil record.

Fossil remains of true finches are rare, and those that are known can mostly be assigned to extant genera at least. Like the other Passeroidea families, the true finches seem to be of roughly Middle Miocene origin, around 20 to 10 million years ago (Ma). An unidentifable finch fossil from the Messinian age, around 12 to 7.3 million years ago (Ma) during the Late Miocene subepoch, has been found at Polgárdi in Hungary.

Etymology.

The scientific name Fringillidae comes from the Latin word "fringilla" for the common chaffinch ("Fringilla coelebs"), a member of the family which is common in Europe. The name was coined (as Fringilladæ) by the English zoologist William Elford Leach in a guide to the contents of the British Museum published in 1820.

Description.

The smallest "classical" true finches are the Andean siskin ("Spinus spinescens") at as little as 9.5 cm (3.8 in) and the lesser goldfinch ("Spinus psaltria") at as little as. The largest species is probably the collared grosbeak ("Mycerobas affinis") at up to and, although larger lengths, to in the pine grosbeak ("Pinicola enucleator"), and weights, to in the evening grosbeak ("Hesperiphona vespertinus"), have been recorded in species which are slightly smaller on average. They typically have strong, stubby beaks, which in some species can be quite large; however, Hawaiian honeycreepers are famous for the wide range of bill shapes and sizes brought about by adaptive radiation. All true finches have 9 primary remiges and 12 rectrices. The basic plumage colour is brownish, sometimes greenish; many have considerable amounts of black, while white plumage is generally absent except as wing-bars or other signalling marks. Bright yellow and red carotenoid pigments are commonplace in this family, and thus blue structural colours are rather rare, as the yellow pigments turn the blue color into green. Many, but by no means all true finches have strong sexual dichromatism, the females typically lacking the bright carotenoid markings of males.

Distribution and habitat.

The finches have a near-global distribution, being found across the Americas, Eurasia and Africa, as well as some island groups such as the Hawaiian islands. They are absent from Australasia, Antarctica, the Southern Pacific and the islands of the Indian Ocean, although some European species have been widely introduced in Australia and New Zealand.  Finches are typically inhabitants of well-wooded areas, but some can be found on mountains or even in deserts.

Behaviour.

The finches are primarily granivorous, but euphoniines include considerable amounts of arthropods and berries in their diet, and Hawaiian honeycreepers evolved to utilize a wide range of food sources, including nectar. The diet of Fringillidae nestlings includes a varying amount of small arthropods. True finches have a bouncing flight like most small passerines, alternating bouts of flapping with gliding on closed wings. Most sing well and several are commonly seen cagebirds; foremost among these is the domesticated canary ("Serinus canaria domestica"). The nests are basket-shaped and usually built in trees, more rarely in bushes, between rocks or on similar substrate.

List of genera.

The family Fringillidae contains 228 species divided into 50 genera and three subfamilies. The subfamily Carduelinae includes 18 extinct Hawaiian honeycreepers and the extinct Bonin grosbeak. See List of Fringillidae species for further details.  Subfamily Fringillinae Subfamily Carduelinae Subfamily Euphoniinae

The true finches are small to medium-sized passerine birds in the family Fringillidae. Finches have stout conical bills adapted for eating seeds and nuts and often have colourful plumage. They occupy a great range of habitats where they are usually resident and do not migrate. They have a worldwide distribution except for Australia and the polar regions. The family Fringillidae contains more than two hundred species divided into fifty genera. It includes species known as siskins, canaries, redpolls, serins, grosbeaks and euphonias.

Pěnkavovití (Fringillidae) je čeleď malých až středně velkých pěvců. Živí se především semeny. Většina druhů krmí mláďata částečně nebo zcela také hmyzem. Jsou to převážně stromoví ptáci, obývají však i otevřené plochy a snadno se přizpůsobují kulturní krajině. Někteří hnízdí v blízkém okolí člověka, a přizpůsobují se tak jeho životnímu prostředí.


History.

Early electric energy was produced near the device or service requiring that energy. In the 1880s, electricity competed with steam, hydraulics, and especially coal gas. Coal gas was first produced on customer's premises but later evolved into gasification plants that enjoyed economies of scale. In the industrialized world, cities had networks of piped gas, used for lighting. But gas lamps produced poor light, wasted heat, made rooms hot and smoky, and gave off hydrogen and carbon monoxide. They also posed a fire hazard. In the 1880s electric lighting soon became advantageous compared to gas lighting.  Electric utility companies took advantage of economies of scale and moved to centralized power generation, distribution, and system management. After the war of the currents was settled in favor of AC power, with long distance power transmission it became possible to interconnect stations to balance load and improve load factors.  In the United Kingdom, Charles Merz, of the Merz & McLellan consulting partnership, built the Neptune Bank Power Station near Newcastle upon Tyne in 1901, and by 1912 had developed into the largest integrated power system in Europe. Merz was appointed head of a Parliamentary Committee and his findings led to the Williamson Report of 1918, which in turn created the Electricity Supply Bill of 1919. The bill was the first step towards an integrated electricity system. The Electricity (Supply) Act of 1926 led to the setting up of the National Grid. The Central Electricity Board standardized the nation's electricity supply and established the first synchronized AC grid, running at 132 kilovolts and 50 Hertz. This started operating as a national system, the National Grid, in 1938.  In the United States in the 1920s, utilities formed joint-operations to share peak load coverage and backup power. In 1934, with the passage of the Public Utility Holding Company Act (USA), electric utilities were recognized as public goods of importance and were given outlined restrictions and regulatory oversight of their operations. The Energy Policy Act of 1992 required transmission line owners to allow electric generation companies open access to their network and led to a restructuring of how the electric industry operated in an effort to create competition in power generation. No longer were electric utilities built as vertical monopolies, where generation, transmission and distribution were handled by a single company. Now, the three stages could be split among various companies, in an effort to provide fair accessibility to high voltage transmission. The Energy Policy Act of 2005 allowed incentives and loan guarantees for alternative energy production and advance innovative technologies that avoided greenhouse emissions.  In France, electrification began in the 1900s, with 700 communes in 1919, and 36,528 in 1938. At the same time, the nearby networks began to interconnect: Paris in 1907 at 12 kV, the Pyrénées in 1923 at 150 kV, and finally almost all of the country interconnected in 1938 at 220 kV. By 1946, the grid is the world's most dense. That year that state nationalised the industry, by uniting the private companies as Électricité de France. The frequency was standardised at 50 Hz, and the 225 kV network replaces 110 and 120. From 1956, service voltage is standardised at 220 / 380 V, replacing the previous 127/220 V. During the 1970s, the 400 kV network, the new European standard, was implemented.

Features.

Voltage.

Grids are designed to supply voltages at largely constant amplitudes. This has to be achieved with varying demand, variable reactive loads, and even nonlinear loads, with electricity provided by generators and distribution and transmission equipment that are not perfectly reliable. Often grids use tap changers on transformers near to the consumers to adjust the voltage and keep it within specification.

Topologies.

Transmission networks are complex with redundant pathways. For example, see the map of the United States' (right) high-voltage transmission network.  The structure, or "topology" of a grid can vary depending on the constraints of budget, requirements for system reliability, and the load and generation characteristics. The physical layout is often forced by what land is available and its geology. Distribution networks are divided into two types, radial or network.  The simplest topology for a distribution or transmission grid is a "radial" structure. This is a "tree" shape where power from a large supply radiates out into progressively lower voltage lines until the destination homes and businesses are reached. However, single failures can take out entire branches of the tree.  Most transmission grids offer the reliability that more complex "mesh networks" provide. The expense of mesh topologies restrict their application to transmission and medium voltage distribution grids. Redundancy allows line failures to occur and power is simply rerouted while workmen repair the damaged and deactivated line.  Other topologies used are "looped" systems found in Europe and "tied ring" networks.  In cities and towns of North America, the grid tends to follow the classic "radially fed" design. A substation receives its power from the transmission network, the power is stepped down with a transformer and sent to a bus from which feeders fan out in all directions across the countryside. These feeders carry three-phase power, and tend to follow the major streets near the substation. As the distance from the substation grows, the fanout continues as smaller laterals spread out to cover areas missed by the feeders. This tree-like structure grows outward from the substation, but for reliability reasons, usually contains at least one unused backup connection to a nearby substation. This connection can be enabled in case of an emergency, so that a portion of a substation's service territory can be alternatively fed by another substation.

Synchronous grid.

A synchronous grid or an "interconnection" is a group of distribution areas all operating with three phase alternating current (AC) frequencies synchronized (so that peaks occur at virtually the same time). This allows transmission of AC power throughout the area, connecting a large number of electricity generators and consumers and potentially enabling more efficient electricity markets and redundant generation.  A large failure in one part of the grid—unless quickly compensated for—can cause current to re-route itself to flow from the remaining generators to consumers over transmission lines of insufficient capacity, causing further failures. One downside to a widely connected grid is thus the possibility of cascading failure and widespread power outage. A central authority is usually designated to facilitate communication and develop protocols to maintain a stable grid. For example, the North American Electric Reliability Corporation gained binding powers in the United States in 2006, and has advisory powers in the applicable parts of Canada and Mexico. The U.S. government has also designated National Interest Electric Transmission Corridors, where it believes transmission bottlenecks have developed.  Some areas, for example rural communities in Alaska, do not operate on a large grid, relying instead on local diesel generators.

Frequency.

In a synchronous grid all the generators must run at the same frequency, and must stay very nearly in phase with each other and the grid. For rotating generators, a local governor regulates the driving torque, maintaining constant speed as loading changes. Droop speed control ensures that multiple parallel generators share load changes in proportion to their rating. Generation and consumption must be balanced across the entire grid, because energy is consumed as it is produced. Energy is stored in the immediate short term by the rotational kinetic energy of the generators.  Small deviations from the nominal system frequency are very important in regulating individual generators and assessing the equilibrium of the grid as a whole. When the grid is heavily loaded, the frequency slows, and governors adjust their generators so that more power is output (droop speed control). When the grid is lightly loaded the grid frequency runs above the nominal frequency, and this is taken as an indication by Automatic Generation Control systems across the network that generators should reduce their output.  In addition, there's often central control, which can change the parameters of the AGC systems over timescales of a minute or longer to further adjust the regional network flows and the operating frequency of the grid. For timekeeping purposes, the nominal frequency will be allowed to vary in the short term, but are adjusted to prevent line-operated clocks from gaining or losing significant time over the course of a whole 24 hour period.  An entire synchronous grid runs at the same frequency, neighbouring grids would not be synchronised even if they run at the same nominal frequency. High-voltage direct current lines or variable-frequency transformers can be used to connect two alternating current interconnection networks which are not synchronized with each other. This provides the benefit of interconnection without the need to synchronize an even wider area. For example, compare the wide area synchronous grid map of Europe with the map of HVDC lines.

Demand.

The demand, or load on an electrical grid is the total electrical power being removed by the users of the grid.  Baseload is the minimum load on the grid over any given period, peak demand is the maximum load. Historically, baseload was commonly met by equipment that was cheap to run, that ran continuously for weeks or months at a time, but globally this is becoming less common. The peak demand requirements are sometimes produced by peaking plants that are generators optimised to come on-line quickly.

Production.

The sum of the power outputs of generators on the grid is the production of the grid, typically measured in gigawatts (GW). The total energy produced is the integral of the power outputs, which is measured in gigawatt hours (GWh).

Transmission losses.

It might be expected that demand and production might be equal, however, in practice power is lost in transmission lines and transformers in the transmission grid, so the demand plus the losses is equal to the production. Where power is being exported or imported to neighbouring grids that power is often considered as a demand or production respectively.

Capacity and firm capacity.

The sum of the maximum power outputs (nameplate capacity) of the generators attached to an electrical grid might be considered to be the capacity of the grid.  However, in practice, they are never run flat out simultaneously. Typically, some generators are kept running at lower output powers (spinning reserve) to deal with failures as well as variation in demand. In addition generators can be off-line for maintenance or other reasons, such as availability of energy inputs (fuel, water, wind, sun etc.) or pollution constraints.  "Firm capacity" is the maximum power output on a grid that is immediately available over a given time period, and is a far more useful figure.

Grid code.

Grid-connected equipment's behaviors are governed by a grid code which is a specification generally provided by the network operator. This ensures the grid stability and in particular specifies the correct behavior in off-nominal scenarios.

Interconnectors.

Electric utilities between regions are many times interconnected for improved economy and reliability. Electrical interconnectors allow for economies of scale, allowing energy to be purchased from large, efficient sources. Utilities can draw power from generator reserves from a different region to ensure continuing, reliable power and diversify their loads. Interconnection also allows regions to have access to cheap bulk energy by receiving power from different sources. For example, one region may be producing cheap hydro power during high water seasons, but in low water seasons, another area may be producing cheaper power through wind, allowing both regions to access cheaper energy sources from one another during different times of the year. Neighboring utilities also help others to maintain the overall system frequency and also help manage tie transfers between utility regions.  Electricity Interconnection Level (EIL) of a grid is the ratio of the total interconnector power to the grid divided by the installed production capacity of the grid. Within the EU, it has set a target of national grids reaching 10% by 2020, and 15% by 2030.

Storage.

"Grid energy storage" (also called "large-scale energy storage") is a collection of methods used to store electrical energy on a large scale within an electrical power grid. Electrical energy is stored during times when production (especially from intermittent power plants such as renewable electricity sources such as wind power, tidal power, solar power) exceeds consumption, and returned to the grid when production falls below consumption. , the largest form of grid energy storage is dammed hydroelectricity, with both conventional hydroelectric generation as well as pumped storage hydroelectricity. Alternatives include rail energy storage, where rail cars carrying large weights are moved up or down a section of inclined rail track, storing or releasing energy as a result; or disused oil-well potential energy storage, where weights are raised or lowered in a deep, decommissioned oil well.  Developments in battery storage have enabled commercially viable projects to store energy during peak production and release during peak demand.  Two alternatives to grid storage are the use of peaking power plants to fill in supply gaps and demand response to shift load to other times.

Failure.

Brownout.

A "brownout" is an intentional or unintentional drop in voltage in an electrical power supply system. Intentional brownouts are used for load reduction in an emergency. The reduction lasts for minutes or hours, as opposed to short-term voltage sag (or dip). The term brownout comes from the dimming experienced by incandescent lighting when the voltage sags. A voltage reduction may be an effect of disruption of an electrical grid, or may occasionally be imposed in an effort to reduce load and prevent a power outage, known as a blackout.

Blackout.

A "power outage" (also called a "power cut", a "power out", a "power blackout", "power failure" or a "blackout") is a loss of the electric power to a particular area.  Power failures can be caused by faults at power stations, damage to electric transmission lines, substations or other parts of the distribution system, a short circuit, cascading failure, fuse or circuit breaker operation, and human error.  Power failures are particularly critical at sites where the environment and public safety are at risk. Institutions such as hospitals, sewage treatment plants, mines, shelters and the like will usually have backup power sources such as standby generators, which will automatically start up when electrical power is lost. Other critical systems, such as telecommunication, are also required to have emergency power. The battery room of a telephone exchange usually has arrays of lead–acid batteries for backup and also a socket for connecting a generator during extended periods of outage.

Load shedding.

Electrical generation and transmission systems may not always meet peak demand requirements— the greatest amount of electricity required by all utility customers within a given region. In these situations, overall demand must be lowered, either by turning off service to some devices or cutting back the supply voltage (brownouts), in order to prevent uncontrolled service disruptions such as power outages (widespread blackouts) or equipment damage. Utilities may impose load shedding on service areas via targeted blackouts, rolling blackouts or by agreements with specific high-use industrial consumers to turn off equipment at times of system-wide peak demand.

Black start.

A "black start" is the process of restoring an electric power station or a part of an electric grid to operation without relying on the external electric power transmission network to recover from a total or partial shutdown.  Normally, the electric power used within the plant is provided from the station's own generators. If all of the plant's main generators are shut down, station service power is provided by drawing power from the grid through the plant's transmission line. However, during a wide-area outage, off-site power from the grid is not available. In the absence of grid power, a so-called black start needs to be performed to bootstrap the power grid into operation.  To provide a black start, some power stations have small diesel generators, normally called the "black start diesel generator" (BSDG), which can be used to start larger generators (of several megawatts capacity), which in turn can be used to start the main power station generators. Generating plants using steam turbines require station service power of up to 10% of their capacity for boiler feedwater pumps, boiler forced-draft combustion air blowers, and for fuel preparation. It is uneconomical to provide such a large standby capacity at each station, so black-start power must be provided over designated tie lines from another station. Often hydroelectric power plants are designated as the black-start sources to restore network interconnections. A hydroelectric station needs very little initial power to start (just enough to open the intake gates and provide excitation current to the generator field coils), and can put a large block of power on line very quickly to allow start-up of fossil-fuel or nuclear stations. Certain types of combustion turbine can be configured for black start, providing another option in places without suitable hydroelectric plants. In 2017 a utility in Southern California has successfully demonstrated the use of a battery energy storage system to provide a black start, firing up a combined cycle gas turbine from an idle state.

Size.

Wide area synchronous grid.

A "wide area synchronous grid" (also called an "interconnection" in North America) is an electrical grid at a regional scale or greater that operates at a synchronized frequency and is electrically tied together during normal system conditions. These are also known as synchronous zones, the largest of which is the synchronous grid of Continental Europe (ENTSO-E) with 667 gigawatts (GW) of generation, and the widest region served being that of the IPS/UPS system serving countries of the former Soviet Union. Synchronous grids with ample capacity facilitate electricity market trading across wide areas. In the ENTSO-E in 2008, over 350,000 megawatt hours were sold per day on the European Energy Exchange (EEX).  Each of the interconnects in North America are run at a nominal 60 Hz, while those of Europe run at 50 Hz. Neighbouring interconnections with the same frequency and standards can be synchronized and directly connected to form a larger interconnection, or they may share power without synchronization via high-voltage direct current power transmission lines (DC ties), or with variable-frequency transformers (VFTs), which permit a controlled flow of energy while also functionally isolating the independent AC frequencies of each side.  The benefits of synchronous zones include pooling of generation, resulting in lower generation costs; pooling of load, resulting in significant equalizing effects; common provisioning of reserves, resulting in cheaper primary and secondary reserve power costs; opening of the market, resulting in possibility of long term contracts and short term power exchanges; and mutual assistance in the event of disturbances.  One disadvantage of a wide-area synchronous grid is that problems in one part can have repercussions across the whole grid. For example, in 2018 Kosovo used more power than it generated due to a row with Serbia, leading to the phase across the whole synchronous grid of Continental Europe lagging behind what it should have been. The frequency dropped to 49.996 Hz. This caused certain kinds of clocks to become six minutes slow.

Microgrid.

A microgrid is a localized group of electricity sources and loads that normally operates connected to and synchronous with the traditional wide area synchronous grid (macrogrid), but can also disconnect to "island mode" – and function autonomously as physical and/or economic conditions dictate.  In this way, a microgrid can effectively integrate various sources of distributed generation, especially renewable energy sources, and can supply emergency power, changing between island and connected modes.  Control and protection are challenges to microgrids.

Super grids.

Various planned and proposed systems to dramatically increase transmission capacity are known as super, or mega grids. The promised benefits include enabling the renewable energy industry to sell electricity to distant markets, the ability to increase usage of intermittent energy sources by balancing them across vast geographical regions, and the removal of congestion that prevents electricity markets from flourishing. Local opposition to siting new lines and the significant cost of these projects are major obstacles to super grids. One study for a European super grid estimates that as much as 750 GW of extra transmission capacity would be required- capacity that would be accommodated in increments of 5 GW HVDC lines. A recent proposal by Transcanada priced a 1,600-km, 3-GW HVDC line at US$3 billion and would require a wide corridor. In India, a recent 6 GW, 1,850-km proposal was priced at $790 million and would require a wide right of way. With 750 GW of new HVDC transmission capacity required for a European super grid, the land and money needed for new transmission lines would be considerable.

Trends.

Increasing electrification.

The number of people with access to grid electricity is growing. About 840 million people (mostly in Africa) had no access to grid electricity in 2017, down from 1.2 billion in 2010.

Demand response.

Demand response is a grid management technique where retail or wholesale customers are requested either electronically or manually to reduce their load. Currently, transmission grid operators use demand response to request load reduction from major energy users such as industrial plants.

Aging infrastructure.

Despite the novel institutional arrangements and network designs of the electrical grid, its power delivery infrastructures suffer aging across the developed world. Contributing factors to the current state of the electric grid and its consequences include:

Modernization.

Thirty-seven states plus the District of Columbia took some action to modernize electric grids in the first quarter of 2017, according to the North Carolina Clean Energy Technology Center. The states did so to make electricity systems "more resilient and interactive". The most common actions that states took were "advanced metering infrastructure deployment" (19 states did this), smart grid deployment and "time-varying rates for residential customers".  Legislatively, in the first quarter of the year 82 relevant bills were introduced in different parts of the United States. At the close of the quarter, most of the bills remained pending. For example, legislators in Hawaii introduced a bill that would create an energy storage tax credit. In California, the state Senate had a bill that would "create a new energy storage rebate program".  In August 2018, Advanced Energy Economy (AEE) and Citizens for Responsible Energy Solutions Forum (CRES Forum) published a policy paper that gave five recommendations on ways to modernize the U.S. electric power grid. These recommendations are to streamline the federal permit process for advanced energy projects; encourage grid planners to consider alternatives to investment in transmission; allow energy storage and energy efficiency to compete with additional energy generation; allow large customers to choose their own sources of electricity; and allow utilities and consumers to benefit from cloud computing software.

Distributed generation.

With everything interconnected, and open competition occurring in a free market economy, it starts to make sense to allow and even encourage distributed generation (DG). Smaller generators, usually not owned by the utility, can be brought on-line to help supply the need for power. The smaller generation facility might be a home-owner with excess power from their solar panel or wind turbine. It might be a small office with a diesel generator. These resources can be brought on-line either at the utility's behest, or by owner of the generation in an effort to sell electricity. Many small generators are allowed to sell electricity back to the grid for the same price they would pay to buy it.  As the 21st century progresses, the electric utility industry seeks to take advantage of novel approaches to meet growing energy demand. Utilities are under pressure to evolve their classic topologies to accommodate distributed generation. As generation becomes more common from rooftop solar and wind generators, the differences between distribution and transmission grids will continue to blur. In July 2017 the CEO of Mercedes-Benz said that the energy industry needs to work better with companies from other industries to form a "total ecosystem", to integrate central and distributed energy resources (DER) to give customers what they want. The electrical grid was originally constructed so that electricity would flow from power providers to consumers. However, with the introduction of DER, power needs to flow both ways on the electric grid, because customers may have power sources such as solar panels.

Smart grid.

The smart grid would be an enhancement of the 20th century electrical grid, using two-way communications and distributed so-called intelligent devices. Two-way flows of electricity and information could improve the delivery network. Research is mainly focused on three systems of a smart grid – the infrastructure system, the management system, and the protection system.  The infrastructure system is the energy, information, and communication infrastructure underlying of the smart grid that supports:  A smart grid would allow the power industry to observe and control parts of the system at higher resolution in time and space. One of the purposes of the smart grid is real time information exchange to make operation as efficient as possible. It would allow management of the grid on all time scales from high-frequency switching devices on a microsecond scale, to wind and solar output variations on a minute scale, to the future effects of the carbon emissions generated by power production on a decade scale.  The management system is the subsystem in smart grid that provides advanced management and control services. Most of the existing works aim to improve energy efficiency, demand profile, utility, cost, and emission, based on the infrastructure by using optimization, machine learning, and game theory. Within the advanced infrastructure framework of smart grid, more and more new management services and applications are expected to emerge and eventually revolutionize consumers' daily lives.  The protection system of a smart grid provides grid reliability analysis, failure protection, and security and privacy protection services. While the additional communication infrastructure of a smart grid provides additional protective and security mechanisms, it also presents a risk of external attack and internal failures. In a report on cyber security of smart grid technology first produced in 2010, and later updated in 2014, the US National Institute of Standards and Technology pointed out that the ability to collect more data about energy use from customer smart meters also raises major privacy concerns, since the information stored at the meter, which is potentially vulnerable to data breaches, can be mined for personal details about customers.  In the U.S., the Energy Policy Act of 2005 and Title XIII of the Energy Independence and Security Act of 2007 are providing funding to encourage smart grid development. The objective is to enable utilities to better predict their needs, and in some cases involve consumers in a time-of-use tariff. Funds have also been allocated to develop more robust energy control technologies.

Grid defection.

As there is some resistance in the electric utility sector to the concepts of distributed generation with various renewable energy sources and microscale cogen units, several authors have warned that mass-scale grid defection is possible because consumers can produce electricity using off grid systems primarily made up of solar photovoltaic technology.  The Rocky Mountain Institute has proposed that there may be widescale grid defection. This is backed up by studies in the Midwest. However, the paper points out that grid defection may be less likely in countries like Germany which have greater power demands in winter.

Utilities and oligopoly.

Due to the enormous capital outlays, utilities were a vertically integrated business throughout the 20th century owning the power generation, the (transmission) lines while also managing the bills (commercialization). Presently, technological progress has enabled individuals and groups to take on the functions that used to be the sole domain of the utility. Adding to the shift is the impact of aging infrastructure on reliability, security and performance factors.

An electrical grid, electric grid or power grid, is an interconnected network for delivering electricity from producers to consumers. It consists of:

Elektrizační soustava je vzájemně propojený soubor zařízení pro výrobu, přenos, transformaci a distribuci elektřiny, včetně elektrických přípojek a přímých vedení, a systémů měřicí, ochranné, řídicí, zabezpečovací, informační a telekomunikační techniky.