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Two Knights Defense

The Two Knights Defense (also called the Prussian Defense) is a chess opening that begins with the moves:
 * 1. e4 e5
 * 2. Nf3 Nc6
 * 3. Bc4 Nf6

First recorded by Giulio Cesare Polerio (c. 1550 – c. 1610) in the late 16th century, this line of the Italian Game was extensively developed in the 19th century. Black's third move is a more aggressive defense than the Giuoco Piano (3...Bc5). Black allows White to attack his f7-pawn with 4.Ng5. If White does so, the game quickly takes on a tactical character: Black is practically forced to give up a pawn for the initiative. The complications are such that David Bronstein suggested that the term "defense" does not fit, and that the name "Chigorin Counterattack" would be more appropriate. The Two Knights has been adopted as Black by many aggressive players including Mikhail Chigorin and Paul Keres, and world champions Mikhail Tal and Boris Spassky. In modern grandmaster play, 3.Bc4 is less common than 3.Bb5, and the more solid 3...Bc5 is the most frequent reply, so the Two Knights Defense is infrequently seen. It remains popular with amateur players. The theory of this opening has been explored extensively in correspondence chess by players such as Hans Berliner and Yakov Estrin.

4.Ng5
German master Siegbert Tarrasch called 4.Ng5 "a real duffer's move" (ein richtiger Stümperzug) and Soviet opening theorist Vasily Panov called it "primitive", but this attack on f7 practically wins a pawn by. Despite Tarrasch's criticism, 4.Ng5 has remained a popular choice for White at all levels.

Main line: 4...d5
After 4...d5 White has little option but to play 5.exd5, since both the bishop and e4-pawn are attacked. Then Black usually plays 5...Na5 but there are other options:
 * The recapture 5...Nxd5 is extremely risky. Albert Pinkus tried to bolster this move with analysis in 1943 and 1944 issues of Chess Review, but White gets a strong attack with either the safe Lolli Attack 6.d4, which Bobby Fischer thought to be very strong, or the sacrificial Fried Liver (or Fegatello) Attack 6.Nxf7 Kxf7 7.Qf3+ Ke6 8.Nc3. These variations are usually considered too difficult for Black to defend, but they are sometimes used in correspondence play. Lawrence Trent describes 5...Nxd5 as "a well-known bad move" (or words to that effect).
 * The Fritz Variation 5...Nd4 and Ulvestad's Variation 5...b5 are related as they share a common subvariation. American master Olav Ulvestad introduced 5...b5 in a 1941 article in Chess Review. White has only one good reply: 6.Bf1!, protecting g2 so White can answer 6...Qxd5 with 7.Nc3. Both replies 6.Bxb5 Qxd5 7.Bxc6+ Qxc6 and 6.dxc6 bxc4 7.Nc3 are weak for White. Black's best response is to transpose to the Fritz Variation with 6...Nd4, making another advantage of 6.Bf1 apparent; the bishop is not attacked as it would be if White had played 6.Be2. German master Alexander Fritz (1857–1932) suggested 5...Nd4 to Carl Schlechter, who wrote about the idea in a 1904 issue of Deutsche Schachzeitung. In 1907 Fritz himself wrote an article about his move in the Swedish journal Tidskrift för Schack. White's best reply is 6.c3, when the game often continues 6...b5 7.Bf1 Nxd5 8.Ne4 or 8.h4.
 * The Berliner Variation, named in honor of IM / GMC Dr. Hans Berliner, continues the Fritz sub-line 8.Ne4 with 8...Qh4, from the famous game Estrin—Berliner, World Correspondence Championship 1965–68, eventually won by Black; this win was pivotal to Berliner's eventual championship victory. That game, which saw Black embark on a very sharp sacrificial path, continued 9.Ng3 Bg4 10.f3 e4 11.cxd4 Bd6 12.Bxb5+ Kd8 13.O-O exf3. IM / GMC Estrin later published, in 1971, the suggestion 14.Qb3!? as an improvement on the game continuation, and this possibility has continued to interest many players.

After 5...Na5, the Polerio Defense, Paul Morphy would play to hold the gambit pawn with 6.d3, the Kieseritzky Attack (or Morphy Variation), which has not been popular, since it has long been known that Black obtains good chances for the pawn with 6...h6 7.Nf3 e4 8.Qe2 Nxc4 9.dxc4 Bc5. (Bronstein once tried the piece sacrifice 8.dxe4!? with success, but its soundness is doubtful. )

Instead, White usually plays 6.Bb5+, when play usually continues 6...c6 (6...Bd7 is also possible ) 7.dxc6 bxc6 8.Be2 h6. (The move 8.Qf3, popular in the nineteenth century and revived by Efim Bogoljubow in the twentieth, can be played instead; Black may reply with 8...h6, 8...Rb8, or 8...Be7.) White then has a choice of retreats for the knight. The usual move here is 9.Nf3, after which Black obtains some initiative after 9...e4 10.Ne5 Bd6 (see diagram). This is the Knorre Variation, and is considered to be the main line of the Two Knights Defense. After ten moves, White has developed only two pieces against Black's three pieces and pawns, but has an extra pawn as well as a better pawn structure. Both 11.d4 and 11.f4 have been tried here with no definitive conclusion. 10...Bc5 is a viable alternative for Black, as is 10...Qc7 (the Goring Variation).

Steinitz favored 9.Nh3 instead, although it did not bring him success in his famous 1891 cable match against Chigorin. The Steinitz Variation was mostly forgotten until Fischer revived it in the 1960s. Nigel Short led a second revival of 9.Nh3 in the 1990s, and today it is thought to be about equal in strength to the more common 9.Nf3. In addition to the moves 8.Be2 and 8.Qf3, the move 8.Bd3 is a valid alternative that has apparently become fashionable in recent years.

Traxler Variation: 4...Bc5
This bold move ignores White's attack on f7 and leads to wild play. Czech problemist Karel Traxler played it against Reinisch in Prague in 1890. Later it was named after Wilkes-Barre, Pennsylvania by Frank Marshall, who claimed to be first to analyze and publish it, so today 4...Bc5 is known as both the Traxler Variation and (in the United States and the United Kingdom only) the Wilkes-Barre Variation.

White can play 5.d4, 5.Nxf7, or 5.Bxf7+:
 * After 5.d4 d5!, White's best move is 6.Bxd5, reapplying the pressure on f7.
 * 5.Nxf7 is very complicated after 5...Bxf2+. The current main lines all are thought to lead to drawn or equal positions, e.g. after 6.Kxf2 Nxe4+ 7.Kg1, or even 7.Ke3.
 * White's best try for an advantage is probably 5.Bxf7+ Ke7 6.Bb3 (although 6.Bd5 was the move recommended by Lawrence Trent), as this poses Black the most problems. No grandmasters have regularly adopted the Wilkes-Barre as Black, but Alexander Beliavsky and Alexei Shirov have played it occasionally even in top competition. No clear refutation is known. A tricky variation is 5.Bxf7+ Kf8!?, where Black plays for one last trick with 6.Bb3 d6 7.Nf7 Qe7. If White plays the seemingly standard 8.Nxh8??, Black is now winning after 8...Bg4!! 9.f3 Nxe4, making use of the pinned f3-pawn. This pawn cannot capture the bishop as 10.fxg4?? Qh4+ 11.g3 Bf2+ wins by force for Black.

4...Nxe4
4...Nxe4?! is considered unsound but must be handled carefully. 5.Nxe4 d5 poses no problems for Black. If 5.Nxf7? Qh4! 6.g3 (6.0-0 Bc5!) 6...Qh3 7.Nxh8 Qg2 8.Rf1 Nd4 9.Qh5+ g6 10.Nxg6 hxg6 11.Qxg6+ Kd8 and Black has dangerous threats. (Alternatively, after 5.Nxf7? Qh4! 6.g3, Black could play more aggressively 6...Nxg3! 7.fxg3 Qe4+ 8.Qe2 Qxh1+ 9.Qf1 Qxf1+ 10.Kxf1 d5 11.Bxd5 Bh3+ 12.Ke1 Nb4 13.Bb3 Nxc2+ 14.Bxc2 Kxf7 with a distinct advantage of material for Black.) Correct is 5.Bxf7+! Ke7 6.d4! (6.d3 is also good) and now:
 * 6...d5 7.Nc3! (best, discovered by Soviet player Lopukhin; White has a clear advantage) 7...Nxc3 8.bxc3 Qd6 (8...Bf5 9.Qf3; 8...e4 9.f3!) 9.a4! Kd8 10.Bg8! Ke8 11.Bxh7± (Estrin).
 * 6...h6 7.Nxe4 Kxf7 and now 8.dxe5 Qe8 9.f4 d6 10.0-0 Kg8 11.Nbc3 dxe5 12. f5 Qf7 13.Nd5 Bd7 14.f6 g6 15.Ne7+! and White has excellent chances (Estrin).

4.d4
White can choose to rapidly with 4.d4 exd4 5.0-0. Now Black can simply by eliminating White's last center pawn with 5...Nxe4, after which White regains the  with 6.Re1 d5 7.Bxd5 Qxd5 8.Nc3, but Black has a comfortable position after 8...Qa5 or 8...Qh5.

The wild Nakhmanson Gambit 6.Nc3 gives White compensation if Black accepts the piece with 6...dxc3 7.Bxf7+ Kxf7 8.Qd5+ and then makes the intuitive move 8...Ke8?! Instead, 8...Kf6! has been analysed to offer Black a substantial edge with best play. Victor Bologan suggests declining the gambit with 6...Nxc3 7.bxc3 d5 8.Bb5 Be7 leading to a better position for Black.

Alternatively, Black can enter the extensively analyzed Max Lange Attack after 5...Bc5 6.e5 d5, which can also arise by transposition from the Giuoco Piano or Scotch Game. White can choose to avoid these lines by playing 5.e5, a line often adopted by Sveshnikov. After 5.e5, either 5...Ne4 or 5...Ng4 is a reply, but most common and natural is 5...d5 6.Bb5 Ne4 7.Nxd4 Bc5, with  play. The tricky 5.Ng5?! is best met by 5...d5! 6.exd5 Qe7+!

Modern Bishop's Opening: 4.d3
The quiet move 4.d3, the Modern Bishop's Opening, transposes into the Giuoco Pianissimo if Black responds 4...Bc5, but there are also independent variations after 4...Be7 or 4...h6. White tries to avoid the tactical battles that are common in other lines of the Two Knights and to enter a more positional game. The resulting positions take on some characteristics of the Ruy Lopez if White plays c3 and retreats the bishop to c2 via Bc4–b3–c2. This move became popular in the 1980s and has been used by John Nunn and others.

Four Knights Variation: 4.Nc3
The attempt to defend the pawn with 4.Nc3 does not work well since Black can take the pawn anyway and use a fork trick to regain the piece, 4.Nc3?! Nxe4! 5.Nxe4 d5. The try 5.Bxf7+? does not help, as Black has the and a better position after 5...Kxf7 6.Nxe4 d5. Instead, 4.Nc3 is usually played with the intent to gambit the e-pawn with the Boden–Kieseritzky Gambit, 4.Nc3 Nxe4 5.0-0. This gambit is not commonly seen in tournament play as it is not well regarded by opening theory, but it can offer White good practical chances, especially in blitz chess.

Chess opening theory table
White must respond to the attack on the e-pawn. (For explanation of notation, see chess opening theory table.)
 * 1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6

title: Two Knights Defense


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Heinrich Roth

Heinrich Roth (also known as Henricus Rodius or Henrique Roa; December 18, 1620 – June 20, 1668) was a missionary and pioneering Sanskrit scholar.

Life
Having been born in Dillingen and raised in Augsburg, where his father Konrad Roth (died 1637) worked as Doctor utriusque iuris for the Prince-Bishopric, from 1635 to 1639 Heinrich Roth studied Rhetoric at the University of Dillingen and Philosophy at the Jesuit college in Innsbruck. In 1639, he became a Jesuit in Landsberg, and from 1641 to 1645 taught at the University of Munich, before returning to Dillingen to start theological studies, which he completed in Ingolstadt in 1649. The same year, he was ordained priest in Eichstätt.

On behalf of Francesco Piccolomini, in 1649 Roth was assigned to the so-called Ethiopian mission to India. Traveling by the land route via Smyrna (1650) and Isfahan, he arrived in Goa by 1652. He worked first on the Island of Salsette off Goa, where from time to time he acted as Portuguese interpreter. He was then sent on an embassy by one of the native princes, and via Uttarakhand finally reached the Mughal Empire and its residence in Agra in 1654. Acting as rector of the Jesuit residence in Agra since 1659, he was involved in the persecution under Shah Jahan and Aurangzeb.

Next to learning the Persian, Kannada and Hindustani languages, Roth at Agra for several years also acquired a profound knowledge of classical Sanskrit grammar and literature from local pandits. The French explorer and philosopher Francois Bernier, who got acquainted with Roth in these years, got to appreciate him as one versed in expert knowledge of the culture and philosophy of religions in India

In 1662, joined by fellow Jesuit Johann Grueber, who was on his way back from China, Roth revisited Europe by the land route via Kabul, and arrived in Rome in February 1664. Athanasius Kircher, in his monumental work China illustrata, published their itinerary, Roth’s description of the Sanskrit alphabet, and some short excerpts of Roth’s other works. Traveling north to Germany, Roth held some public lectures in Neuburg on the history and culture of the Mughal Empire, excerpts of which subsequently appeared in print. In Vienna, Roth succeeded in gaining financial support from emperor Leopold I to have his Sanskrit grammar – the first such work ever compiled by a European, which Roth had completed in Agra by 1660 – appear in print, but the project was stopped by the Jesuit Superior General Giovanni Paolo Oliva.

Ordered by Oliva to set up a Jesuit mission in Nepal, Roth traveled back via Constantinople and Surat, returning to Agra by 1666, where he died in 1668 before he could embark on the Nepalese mission. His gravesite is still visible at the Padri Santos chapel in Lashkarpur, a suburb of Agra.

Work
Heinrich Roth's Sanskrit grammar, that he had completed by 1660 in Latin language under the title Grammatica Linguae Sanscretanae Brachmanum Indiae Orientalis (the manuscript of which is preserved today at the Biblioteca Nazionale Centrale in Rome) and that was augmented by preliminary studies for a complete Sanskrit-Latin dictionary, made him a pioneering scholar in modern Sanskrit studies in Europe. Further works include studies on the Hindustani and Devanagari alphabets, on Vedanta and on Vishnu. Also, a total of 35 letters, written by Roth from India and during his travel back to Europe, survive at the Royal Library of Belgium in Brussels.

Editions of Roth’s work

 * Arnulf Camps/Jean-Claude Muller (Edd.), The Sanskrit grammar and manuscripts of Father Heinrich Roth, S.J. (1620–1668). Facsimile edition of Biblioteca Nazionale, Rome, Mss. Or. 171 and 172, Leiden, 1988. (includes a complete list of Roth’s surviving works and references to where parts of them have previously been printed)

Studies on Roth

 * Arnulf Camps, The Sanskrit Grammar and Manuscripts of Father Heinrich Roth S. J. (1620–1668). Introduction. The History of his Sanskrit Manuscripts. In: Arnulf Camps, Studies in Asian mission history 1956-1998, Leiden/Boston/Köln, 2000, pp. 84–104.
 * Pierre-Sylvain Filliozat, "L’approche scientifique du sanscrit et de la pensée indienne par Heinrich Roth, S.J. au XVIIe siècle", In: Id. & Jean Leclant eds, L’œuvre scientifique des missionnaires en Asie, Paris : Académie des Inscriptions et Belles-Lettres, 2012, pp. 17-30.
 * Veronika Lukas ∙ Julius Oswald SJ ∙ Claudia Wiener (eds), Ein Dillinger in Indien: P. Heinrich Roth SJ (1620-1668), erscheint zugleich als Jahrbuch des Historischen Vereins Dillingen a. d. Donau 121. Jahrgang 2020 (Jesuitica 26), Regensburg : Schnell & Steiner, 2022.
 * Claus Vogel, Heinrich Roth, in: Neue Deutsche Biographie 22, 2005, pp. 106 sq. (German) online
 * Claus Vogel, The Jesuit missionary Heinrich Roth (1620–1668) and his burial place at Agra. In: Lars Göhler (Ed.): Indische Kultur im Kontext. Rituale, Texte und Ideen aus Indien und der Welt. Festschrift für Klaus Mylius.Wiesbaden, 2005, pp. 407–412.
 * Claus Vogel, An old letter from Surat written by German Jesuit Heinrich Roth. In: Annals of the Bhandarkar Oriental Research Institute 58, 1987, pp. 609–619.
 * Claus Vogel, Die Vorarbeiten des Jesuitenmissionars Heinrich Roth (1620–1668) zu einem Sanskrit-lateinischen Wörterbuch. In: Helmut Eimer (Ed.): Vicitrakusumañjali. Festschrift für Richard Othon Meisezahl anläßlich seines achtzigsten Geburtstages. Bonn, 1986, pp. 131–146. Shortened English version: Claus Vogel, The preliminary work done by Heinrich Roth (1620–1668) on a Sanskrit-Latin dictionary. In: Aligarh Journal of Oriental Studies 4, No. 1, 1987, pp. 69–74.
 * Bruno Zimmel, P. Heinrich Roths SJ Expedition nach Nepal. In: Jahrbuch des Historischen Vereins Dillingen an der Donau 70, 1968, pp. 64-78 (German).

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

title: Heinrich Roth


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Honshū–Shikoku Bridge Project

The Honshu-Shikoku Bridge Project (本州四国連絡橋) is a system of bridges connecting the islands of Honshu and Shikoku across the Inland Sea of Japan, which were previously only connected by ferry. It consists of three major connections. All bridges are now controlled by the Honshu-Shikoku Bridge Expressway Company and the Japan Expressway Holding and Debt Repayment Agency (日本高速道路保有・債務返済機構). The system consists of three expressways and their respective bridge systems.

Kobe-Awaji-Naruto Expressway
The eastern expressway was completed in 1998. Crossing the Akashi Strait, this connection links Hyōgo Prefecture on Honshu with Tokushima Prefecture on Shikoku, using Awaji Island for most of its length. The route connects to the Sanyō Expressway at its northern terminus, allowing traffic to connect to Himeji, Kobe, and other major cities on Honshū.

This connection uses three suspension bridges. The Akashi Kaikyō Bridge was the world's longest suspension bridge, and connects Kobe to Awaji Island (Awaji, Hyogo). The others are the Ōnaruto Bridge, connecting Awaji to Ōge Island (Naruto, Tokushima) across the Naruto Strait, and the Muya Bridge connecting Ōge Island with Shikoku.

Although the connection was initially designed to accommodate railway service as well as road traffic, economic considerations turned it into a road connection only.

Seto-Chūō Expressway
The central expressway was completed in 1988. Also known as the Great Seto Bridge, this line connects Okayama Prefecture to Kagawa Prefecture. A series of six major bridges and five viaducts are used. The six bridges are the Shimotsui-Seto Bridge, Hitsuishijima Bridge, the Iwakurojima Bridge, the Yoshima Bridge, the Kita Bisan-Seto Bridge, and the Minami Bisan-Seto Bridge.

The Seto-Chūō bridges are also used by JR trains (Seto-Ōhashi Line), and are designed to accommodate high-speed Shinkansen service in the future, although there are no current plans to extend the Shinkansen to Shikoku.

Nishiseto Expressway
The western expressway was completed in 1999. Commonly known as the Shimanami Kaidō, this connection links Hiroshima Prefecture to Ehime Prefecture. The link consists of nine bridges: the Shin-Onomichi Bridge, Innoshima Bridge, Ikuchi Bridge, Tatara Bridge, Ōmishima Bridge, Hakata-Ōshima Bridge, and the three-part Kurushima-Kaikyō Bridge. It is the only route that can be crossed on bicycle or by foot.

title: Honshū–Shikoku Bridge Project


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King's Gambit

The King's Gambit is a chess opening that begins with the moves:
 * 1. e4 e5
 * 2. f4

White offers a pawn to divert the black e-pawn. If Black accepts the gambit, White may play d4 and Bxf4, regaining the gambit pawn with domination, or direct their forces against the weak square f7 with moves such as Nf3, Bc4, 0-0, and g3. A downside to the King's Gambit is that it weakens White's king's position, exposing it to the latent threat of ...Qh4+ (or ...Be7–h4+), which may force White to give up castling rights.

The King's Gambit is one of the oldest documented openings, appearing in one of the earliest chess books, Luis Ramírez de Lucena's Repetición de Amores y Arte de Ajedrez (1497). It was examined by the 17th-century Italian chess player Giulio Cesare Polerio. The King's Gambit was one of the most popular openings until the late 19th century, when improvements in defensive technique led to its decline in popularity. It is infrequently seen at master level today, as Black has several methods to obtain, but is still popular at amateur level.

History
The King's Gambit was one of the most popular openings for over 300 years, and has been played by many of the strongest players in many of the greatest, including the Immortal Game. Nevertheless, players have held widely divergent views on it. François-André Danican Philidor (1726–1795), the greatest player and theorist of his day, wrote that the King's Gambit should end in a draw with best play by both sides, stating that "a gambit equally well attacked and defended is never a decisive [game], either on one side or the other." Writing over 150 years later, Siegbert Tarrasch, one of the world's strongest players in the late 19th and early 20th centuries, pronounced the opening "a decisive mistake" and wrote that "it is almost madness to play the King's Gambit." Similarly, future world champion Bobby Fischer wrote a famous article, "A Bust to the King's Gambit", in which he stated, "In my opinion the King's Gambit is busted. It loses by force" and offered his Fischer Defense (3...d6) as a refutation. FM Graham Burgess, in his book The Mammoth Book of Chess, noted the discrepancy between the King's Gambit and Wilhelm Steinitz's accumulation theory. Steinitz had argued that an attack is only justified when a player has an advantage, and an advantage is only obtainable after the opponent makes a mistake. Since 1...e5 does not look like a blunder, White should therefore not be launching an attack.

While the King's Gambit Accepted was a staple of Romantic era chess, the opening began to decline with the development of opening theory and improvements in defensive technique in the late 19th century. By the 1920s, 1.e4 openings declined in popularity with the rise of the hypermodern school, with many players switching to 1.d4 and 1.c4 openings and. After World War II, 1.e4 openings became more popular again, with David Bronstein being the first grandmaster in decades to use the King's Gambit in serious play. He inspired Boris Spassky to also take up the King's Gambit, although Spassky was not willing to risk using the opening in any of his World Championship matches. Spassky did beat many strong players with it, however, including Bobby Fischer, Zsuzsa Polgar, and a famous against Bronstein himself.

In 2012, an April Fools' Day prank by Chessbase in association with Vasik Rajlich—author of chess engine Rybka—claimed to have proven to a 99.99999999% certainty that the King's Gambit is at best a draw for White, but only after 3.Be2. Revealing the prank, Rajlich admitted that current computer technology is nowhere near solving such a task.

The King's Gambit is rare in modern high-level play. The main reason is that it is hard to gain an opening advantage with White against strong opponents, with GM Matthew Sadler once joking that the dream of every King's Gambit player is a "worse but holdable ending". A handful of grandmasters have continued to use it, including Joseph Gallagher, Hikaru Nakamura, Baskaran Adhiban, Nigel Short, and Alexei Fedorov, albeit never as a main weapon.

King's Gambit Accepted: 2...exf4
Although Black usually accepts the gambit pawn, two methods of declining the gambit—the Classical Defense (2...Bc5) and the Falkbeer Countergambit (2...d5)—are also popular. After 2...exf4, the two main continuations for White are 3.Nf3 (King's Knight's Gambit) and 3.Bc4 (Bishop's Gambit).

King's Knight's Gambit: 3.Nf3
This is the most popular move. It develops the knight and prevents 3...Qh4+. Black's two main approaches are to attempt to hold on to the pawn with ...g5, or to return the pawn in order to facilitate.

Classical Variation: 3...g5
The Classical Variation arises after 3.Nf3 g5. Black defends the f4-pawn, and threatens to kick the f3-knight with ...g4, or else to consolidate with ...Bg7 and ...h6. The main continuations traditionally have been 4.h4 and 4.Bc4. More recently, 4.Nc3 (the Quaade Gambit or Quaade Attack) has been recommended by Scottish grandmaster (GM) John Shaw as a less explored alternative to 4.h4 and superior to 4.Bc4.

4.h4: Kieseritzky Gambit and Allgaier Gambit
With 4.h4 White practically forces 4...g4, thereby undermining any attempt by Black to set up a stable pawn chain with ...h6 and ...Bg7.

The Kieseritzky Gambit, 4.h4 g4 5.Ne5, is considered by modern writers such as Shaw and Gallagher to be the main line after 3...g5. It was popularized by Lionel Kieseritzky in the 1840s and used successfully by Wilhelm Steinitz. Boris Spassky used it to beat Bobby Fischer in a famous game at Mar del Plata in 1960. The main line of the Kieseritzky Gambit is considered to be 5...Nf6 (Berlin Defense) 6.Bc4 d5 7.exd5 Bd6 8.d4 Nh5 9.0-0 Qxh4 10.Qe1 Qxe1 11.Rxe1 0-0 12.Bb3 Bf5. The Long Whip Variation, 5...h5?! 6.Bc4 Rh7 (or 6...Nh6) is considered old-fashioned and risky, as Black loses a lot of time attempting to hold on to the pawn.

4.h4 g4 5.Ng5 is the Allgaier Gambit, intending 5...h6 6.Nxf7. This knight sacrifice is considered unsound.

4.Bc4 g4: Muzio Gambit and others
The extremely Muzio Gambit arises after 4.Bc4 g4 5.0-0 gxf3 6.Qxf3, where White has sacrificed a knight but has three pieces bearing down on f7. Such wild play is rare in modern chess, but Black must defend accurately. Perhaps the sharpest continuation is the Double Muzio after 6...Qf6 7.e5 Qxe5 8.Bxf7+, leaving White two pieces down in eight moves, but with a position that some masters consider to be equal. In practice White's play seems to be easier, especially when the opponent is surprised by such daring tactics.

Similar lines are the Ghulam Kassim Gambit, 4.Bc4 g4 5.d4, and the McDonnell Gambit, 4.Bc4 g4 5.Nc3. These are generally considered inferior to the Muzio, which has the advantage of reinforcing White's attack along the f-file. Also inferior is the Lolli Gambit 4.Bc4 g4 5.Bxf7+, which leaves White with insufficient compensation for the piece after 5...Kxf7 6.Ne5+ Ke8 7.Qxg4 Nf6 8.Qxf4 d6.

The Salvio Gambit, 4.Bc4 g4 5.Ne5 Qh4+ 6.Kf1, is considered better for Black due to the insecurity of White's king. Black may play safely with 6...Nh6 (Silberschmidt Variation), or counter-sacrifice with 6...f3 (Cochrane Gambit) or 6...Nc6 (Viennese Variation).

4.Bc4 Bg7: Hanstein Gambit and Philidor Gambit
A safer alternative to 4...g4 is 4...Bg7, which usually leads to the Hanstein Gambit after 5.d4 d6 6.0-0 h6 or the Philidor Gambit after 5.h4 h6 6.d4 d6 (other move orders are possible in both cases).

4.Nc3: Quaade Gambit
The Quaade Gambit (3.Nf3 g5 4.Nc3) is named after a Danish amateur who discussed it in correspondence with the Deutsche Schachzeitung in the 1880s. The move has received renewed attention following its recommendation by John Shaw in his 2013 book on the King's Gambit. A well-known trap here is 4...g4 5.Ne5 Qh4+ 6.g3 fxg3 7.Qxg4 g2+ (7...Qxg4 8.Nxg4 d5 is about equal) 8.Qxh4 gxh1=Q 9.Qh5 and White is close to winning. (Black's best defense is considered 9...Nh6 10.d4 d6 11.Bxh6 dxe5 12.Qxe5+ Be6 13.Qxh8 Nd7 14.Bxf8 0-0-0 and White will emerge a clear pawn ahead.) Instead, 4...Bg7 has been recommended. 4...d6 and 4...h6 transpose to Fischer's Defense and Becker's Defense, respectively. Also possible is 4...Nc6, recommended by Konstantin Sakaev.

After 4...Bg7 5.d4 g4, Simon Williams advocates 6.Bxf4 gxf3 in his DVD and Chess.com video series. White is down a knight, but has a strong attack. The Quaade Gambit has recently been advocated by Daniel King in his PowerPlay series for Chessbase.

4.d4: Rosentreter Gambit
This is likely to lead to similar positions to the Quaade Gambit; however, 4...g4 5.Ne5 Qh4+ 6.g3 fxg3 7.Qxg4 g2+!? (7...Qxg4=) is now viable due to the threat against the pawn on e4. After 8.Qxh4 gxh1=Q Shaw recommends 9.Nc3 for White, with a complicated position.

Becker Defense: 3...h6
The Becker Defense (3.Nf3 h6), has the idea of creating a on h6, g5, f4 to defend the f4 pawn while avoiding the Kieseritzky Gambit, so Black will not be forced to play ...g4 when White plays to undermine the chain with h4. White has the option of 4.b3, although the main line continues with 4.d4 g5 (ECO C37) and usually transposes to lines of the Classical Variation after 5.Bc4 Bg7 6.0-0 (ECO C38).

Bonch-Osmolovsky Defense: 3...Ne7
The rarely seen Bonch-Osmolovsky Defense (3.Nf3 Ne7) aims to defend the f4-pawn with ...Ng6, a relatively safe square for the knight compared to the Schallopp Defense. It was played by Mark Bluvshtein to defeat former world title finalist Nigel Short at Montreal 2007, even though it has never been highly regarded by theory.

Cunningham Defense: 3...Be7
The Cunningham Defense (3.Nf3 Be7) threatens a check on h4 that can permanently prevent White from castling; furthermore, if White does not immediately develop the king's bishop, Ke2 would be forced, which hems the bishop in. A sample line is 4.Nc3 Bh4+ 5.Ke2 d5 6.Nxd5 Nf6 7.Nxf6+ Qxf6 8.d4 Bg4 9.Qd2. White has strong central control with pawns on d4 and e4, while Black is relying on the white king's discomfort to compensate.

To avoid having to play Ke2, 4.Bc4 is White's most popular response. Black can play 4...Bh4+ anyway, forcing 5.Kf1 (or else the wild Bertin Gambit or Three Pawns' Gambit, 5.g3 fxg3 6.0-0 gxh2+ 7.Kh1, played in the nineteenth century). In modern practice, it is more common for Black to simply develop instead with 4...Nf6 5.e5 Ng4, known as the Modern Cunningham. An under-explored but seemingly playable line here is 5...Ne4!?, the Euwe Variation, which has a number of trappy ideas.

Schallopp Defense: 3...Nf6
The Schallopp Defense (3.Nf3 Nf6) is usually played with the intention of holding on to the pawn after 4.e5 Nh5. While it is not Black's most popular option, it attracted some attention in 2020 when Ding Liren used it to beat Magnus Carlsen in the online Magnus Carlsen Invitational tournament. The undefended knight on h5 means Black must be careful: for example 4.e5 Nh5 5.d4 d6 6.Qe2 Be7? (correct is 6...d5!=) 7.exd6 Qxd6 8.Qb5+ wins the h5-knight.

Modern Defense: 3...d5
The Modern Defense, or Abbazia Defense, (3.Nf3 d5) has much the same idea as the Falkbeer Countergambit, and can in fact be reached via transposition, i.e. 2...d5 3.exd5 exf4 4.Nf3. Black concentrates on gaining piece play and fighting for the initiative rather than keeping the extra pawn. It has been recommended by several publications as an easy way to equalize, although White's extra central pawn and piece activity gives a slight advantage. If White captures (4.exd5) then Black may play 4...Nf6 or recapture with 4...Qxd5, at which point it becomes the Scandinavian Variation of. This variation was considered most critical in the past, but recent trends seem to indicate a slight advantage for White.

Fischer Defense: 3...d6
"The refutation of any gambit begins with accepting it. In my opinion the King's Gambit is busted. It loses by force." — R. Fischer, "A Bust to the King's Gambit"

The Fischer Defense (3.Nf3 d6), although previously known, was advocated by Bobby Fischer after he was defeated by Boris Spassky in a Kieseritzky Gambit at the 1960 Mar del Plata tournament. Fischer then decided to refute the King's Gambit, and the next year the American Chess Quarterly published his analysis of 3...d6, which he called "a high-class waiting move".

The point is that after 4.d4 g5 5.h4 g4 White cannot continue with 6.Ne5 as in the Kieseritzky Gambit, 6.Ng5 is unsound because of 6...f6 trapping the knight, and 6.Nfd2 blocks the bishop on c1. This leaves the move 6.Ng1 as the only option, when after six moves neither side has developed a piece. The resulting slightly odd position offers White good attacking chances. A typical continuation is 6.Ng1 Bh6 7.Ne2 Qf6 8.Nbc3 c6 9.g3 f3 10.Nf4 Qe7 with an unclear position (Korchnoi/Zak).

The main alternative to 4.d4 is 4.Bc4. Play usually continues 4...h6 5.d4 g5 6.0-0 Bg7, transposing into the Hanstein Gambit, which can also be reached via 3...g5 or 3...h6.

MacLeod Defense: 3...Nc6
The MacLeod Defense, 3...Nc6, is named after Nicholas MacLeod. Joe Gallagher writes that 3.Nf3 Nc6 "has never really caught on, probably because it does nothing to address Black's immediate problems." Like Fischer's Defense, it is a. An obvious drawback is that the knight on c6 may prove a target for the d-pawn later in the opening.

Wagenbach Defense: 3...h5
An invention of the Hungarian/English player, János Wagenbach. John Shaw writes: "If given the time, Black intends to seal up the kingside with ...h4 followed by ...g5, securing the extra pawn on f4 without allowing an undermining h2–h4. The drawback is of course the amount of time required".

Bishop's Gambit: 3.Bc4
Of the alternatives to 3.Nf3, the most important is the Bishop's Gambit, 3.Bc4. White allows 3...Qh4+ 4.Kf1, losing the right to castle, but this loses time for Black after the inevitable Nf3 and White will develop rapidly. White also has the option of delaying Nf3, however, and can instead play g3, after which the game becomes quite sharp, with White having the option of Qf3 with an attack on f7, or Kg2 threatening hxg3. This idea is advocated, among others, by GM Simon Williams.

Korchnoi and Zak recommend as best for Black 3...Nf6 4.Nc3 c6, or the alternative move order 3...c6 4.Nc3 Nf6. After 5.Bb3 d5 6.exd5 cxd5 7.d4 Bd6 8.Nge2 0-0 9.0-0 g5 10.Nxd5 Nc6, Black was somewhat better in Spielmann–Bogoljubow, Märisch Ostrau 1923.

Black's other main option is 3...d5, returning the pawn immediately. Play might continue 3...d5 4.Bxd5 Nf6 5.Nc3 Bb4 6.Nf3 Bxc3 7.dxc3 c6 8.Bc4 Qxd1+ 9.Kxd1 0-0 10.Bxf4 Nxe4 with an equal position (Bilguer Handbuch, Korchnoi/Zak).

3...Nc6!?, Maurian Defense, is relatively untested, but if White plays 4.Nf3 Black can transpose into the Hanstein Gambit after 4...g5 5.d4 Bg7 6.c3 d6 7.0-0 h6 (Neil McDonald, 1998). John Shaw wrote that 3...Nc6 is a "refutation" of the Bishop's Gambit, as he says that Black is better in all variations.

Steinitz's 3...Ne7 and the 3...f5 (best met by 4.Qe2!) are generally considered inferior.

Other 3rd moves for White
Other 3rd moves for White are rarely played. Some of these are:
 * 3.Nc3 (Mason Gambit or Keres Gambit)
 * 3.d4 (Villemson Gambit or Steinitz Gambit)
 * 3.Be2 (Lesser Bishop's Gambit or Tartakower Gambit)
 * 3.Qf3 (Breyer Gambit or Hungarian Gambit)
 * 3.Qe2 (Basman Gambit)
 * 3.g3 (Gama Gambit)
 * 3.h4 (Stamma Gambit)
 * 3.Nh3 (Eisenberg Gambit)
 * 3.Kf2?! (The Tumbleweed)

King's Gambit Declined
Black can decline the offered pawn, or offer a.

Falkbeer Countergambit: 2...d5
The Falkbeer Countergambit is named after the 19th-century Austrian master Ernst Falkbeer. It runs 1.e4 e5 2.f4 d5 3.exd5 e4, in which Black sacrifices a pawn in return for quick and easy development. It was once considered good for Black and scored well, but White obtains some advantage with the response 4.d3!, and the line fell out of favor after the 1930s.

A more modern interpretation of the Falkbeer is 2...d5 3.exd5 c6!?, as advocated by Aron Nimzowitsch. Black is not concerned about pawns and aims for early piece activity. White has a better pawn structure and prospects of a better endgame. The main line continues 4.Nc3 exf4 5.Nf3 Bd6 6.d4 Ne7 7.dxc6 Nbxc6, giving positions analogous to the Modern Variation of the gambit accepted.

Classical Defense: 2...Bc5
A common way to decline the gambit is with 2...Bc5, the "classical". The bishop prevents White from castling and is such a nuisance that White often expends two tempi to eliminate it by means of Nc3–a4, to exchange on c5 or b6, after which White may castle without worry. It also contains an opening trap for novices: if White continues with 3.fxe5 Black continues 3...Qh4+, in which either the rook is lost (4.g3 Qxe4+, forking the rook and king) or White is checkmated (4.Ke2 Qxe4#). This line often comes about by transposition from lines of the Vienna Game or Bishop's Opening, when White plays f2–f4 before Nf3.

One rarely seen line is the Rotlewi Countergambit: 3.Nf3 d6 4.b4. The idea of the gambit is similar to that seen in the Evans Gambit of the Italian Game. White sacrifices a pawn to try to build a strong center with 4...Bxb4 5.c3 Bc5 (or 5...Ba5) 6.fxe5 dxe5 7.d4. This line is considered slightly dubious, however.

Other 2nd moves for Black
Other options in the KGD are possible, though unusual, such as the Adelaide Countergambit 2...Nc6 3.Nf3 f5, advocated by Tony Miles; 2...d6, which is the way the King’s Gambit was declined the first known time it was played, when after 3.Nf3, best is 3...exf4 transposing to the Fischer Defense (though 2...d6 invites White to play 3.d4 instead); and 2...Nf6 3.fxe5 Nxe4 4.Nf3 Ng5! 5.d4 Nxf3+ 6.Qxf3 Qh4+ 7.Qf2 Qxf2+ 8.Kxf2 with a small endgame advantage, as played in the 1968 game between Bobby Fischer and Bob Wade in Vinkovci. The greedy 2...Qf6 (known as the Nordwalde Variation), intending 3...Qxf4, is considered dubious. Also dubious are the Keene Defense: 2...Qh4+ 3.g3 Qe7 and the Mafia Defense: 1.e4 e5 2.f4 c5.

2...f5 is among the oldest countergambits in KGD, known from a game published in 1625 by Gioachino Greco. Vincenz Hruby also played it against Mikhail Chigorin in 1882. It is nonetheless considered dubious because 3.exf5 with the threat of Qh5+ gives White a good game. The variation is sometimes named the Pantelidakis Countergambit because GM Larry Evans answered a question from Peter Pantelidakis of Chicago about it in one of his columns in Chess Life and Review.

Related lines
In several lines of the Vienna Game White offers a sort of delayed King's Gambit. In the Vienna Gambit (1.e4 e5 2.Nc3 Nf6 3.f4), Black should reply 3...d5, since 3....exf4 4.e5 forces the knight to retreat. 1.e4 e5 2.Nc3 Nc6 3.f4 exf4 may lead to the Hamppe–Muzio Gambit after 4.Nf3 g5 5.Bc4 g4 6.0-0 gxf3 7.Qxf3, or to the Steinitz Gambit after 4.d4 Qh4+ 5.Ke2. Both of these lines may be reached via the King's Gambit proper, but the Vienna move order is more common.

White may also offer the gambit in the Bishop's Opening, e.g. 1.e4 e5 2.Bc4 Nc6 3.f4, though this is uncommon.

ECO
The Encyclopaedia of Chess Openings has ten codes for the King's Gambit, C30 through C39.
 * C30: 1.e4 e5 2.f4 (King's Gambit)

 * C31: 1.e4 e5 2.f4 d5 (Falkbeer Countergambit)

 * C32: 1.e4 e5 2.f4 d5 3.exd5 e4 4.d3 Nf6 (Morphy, Charousek, etc.)
 * C33: 1.e4 e5 2.f4 exf4 (King's Gambit Accepted)
 * C34: 1.e4 e5 2.f4 exf4 3.Nf3 (King's Knight's Gambit)
 * C35: 1.e4 e5 2.f4 exf4 3.Nf3 Be7 (Cunningham Defense)
 * C36: 1.e4 e5 2.f4 exf4 3.Nf3 d5 (Abbazia Defense)
 * C37: 1.e4 e5 2.f4 exf4 3.Nf3 g5 4.Nc3 /4.Bc4 g4 5.0-0 (Muzio Gambit)
 * C38: 1.e4 e5 2.f4 exf4 3.Nf3 g5 4.Bc4 Bg7 (Philidor, Hanstein, etc.)
 * C39: 1.e4 e5 2.f4 exf4 3.Nf3 g5 4.h4 (Allgaier, Kieseritzky, etc.)

title: King's Gambit


text:
Sicilian Defence

The Sicilian Defence is a chess opening that begins with the following moves:
 * 1. e4 c5

The Sicilian is the most popular and best-scoring response to White's first move 1.e4. The opening 1.d4 is a statistically more successful opening for White because of the high success rate of the Sicilian defence against 1.e4. New In Chess stated in its 2000 Yearbook that, of the games in its database, White scored 56.1% in 296,200 games beginning 1.d4, but 54.1% in 349,855 games beginning 1.e4, mainly because the Sicilian held White to a 52.3% score in 145,996 games.

17% of all games between grandmasters, and 25% of the games in the Chess Informant database, begin with the Sicilian.

Grandmaster John Nunn attributes the Sicilian Defence's popularity to its "combative nature": "in many lines Black is playing not just for equality, but for the advantage. The drawback is that White often obtains an early initiative, so Black has to take care not to fall victim to a quick attack." Grandmaster Jonathan Rowson considered why the Sicilian is the most successful response to 1.e4, even though 1...c5 develops no pieces and the pawn on c5 controls only d4 and b4. Rowson writes:

"To my mind there is quite a straightforward explanation. To profit from the initiative granted by the first move, White has to make use of his opportunity to do something before Black has an equal number of opportunities of his own. However, to do this, he has to make 'contact' with the black position. The first point of contact usually comes in the form of a pawn exchange, which leads to the opening of the position. ... So the thought behind 1...c5 is this: 'OK, I'll let you open the position, and develop your pieces aggressively, but at a price – you have to give me one of your center pawns.'"

The earliest recorded notes on the Sicilian Defence date back to the late 16th century by the Italian chess players Giulio Polerio and Gioachino Greco.

General concepts
By advancing the c-pawn two squares, Black asserts control over the d4-square and begins the fight for the. The move resembles 1…e5, the next most common response to 1.e4, in that respect. Unlike 1...e5, however, 1...c5 breaks the of the position, which strongly influences both players' future actions. White, having pushed a pawn, tends to hold the initiative on that side of the board. However, 1...c5 does little for Black's, unlike moves such as 1...e5, 1...g6, or 1...Nc6, which either develop a minor piece or prepare to do so. In many variations of the Sicilian, Black makes a number of further pawn moves in the opening (for example, ...d6, ...e6, ...a6, and ...b5). Consequently, White often obtains a substantial lead in development and dangerous attacking chances.

Meanwhile, advancing a pawn has given Black a  there and provides a basis for future operations on that flank. Often, Black's c5-pawn is traded for White's d4-pawn in the early stages of the game, granting Black a central. The pawn trade also opens the c- for Black, who can place a rook or queen on that file to support the queenside. In many variations, White castles queenside to exploit attacking chances on the kingside at the cost of moving his king to the flank where Black has a spatial advantage.

History
The Sicilian Defence was analysed by Giulio Polerio in his 1594 manuscript on chess, though he did not use the term 'Sicilian Defence'. It was later the subject of analyses by leading players of the day Alessandro Salvio (1604), Don Pietro Carrera (c. 1617), and Gioachino Greco (1623), and later Conte Carlo Francesco Cozio (c. 1740). The great French player and theoretician André Danican Philidor opined of the Sicilian in 1777, "This way of opening the game ... is absolutely defensive, and very far from being the best ... but it is a very good one to try the strength of an adversary with whose skill you are unacquainted."

In 1813, the English master Jacob Henry Sarratt effectively standardised his English translation of the name of this opening as 'the Sicilian Defence', referring to an old Italian manuscript that used the phrase il gioco siciliano ('the Sicilian game'). The Sicilian was fairly popular for much of the nineteenth century; Louis-Charles Mahé de La Bourdonnais, Adolf Anderssen, Howard Staunton, Louis Paulsen, and Carl Jaenisch all played it with some consistency. In the ninth edition of Modern Chess Openings, Walter Korn noted that the Sicilian "received three of its earliest practical tests, and a big boost in popularity, in the 1834 La Bourdonnais – McDonnell chess matches, 1843 Staunton–St. Amant match, and the London 1851 chess tournament." Staunton wrote of the Sicilian, "In the opinion of Jaenisch and the German Handbuch, with which I coincide, this is the best possible reply to 1.P-K4, [1.e4 in algebraic notation] 'as it renders the formation of a centre impracticable for White and prevents every attack'."

The opening fell out of favour in the later part of the nineteenth century, when some of the world's leading players rejected it. Paul Morphy, the world's best player in the late 1850s, decried "that pernicious fondness for the Sicilian Defense ... extending from about 1843 to some time after 1851". Wilhelm Steinitz, the first World Champion, also disliked the Sicilian and rejected it in favour of 1...e5. The death of the opening's two greatest proponents, Staunton and Anderssen, in 1874 and 1879 respectively, also contributed to its decline. It has been said that "these losses almost dealt a knockout blow to the Sicilian because it took a long time to find such important figures to carry the Sicilian's standard." George H. D. Gossip, in The Chess Player's Manual, first published in 1874, wrote, "Of late years ... discoveries have been made which have the effect of considerably strengthening White's attack, and the 'Sicilian' is now considered by most modern authorities to be a comparatively weak mode of play." Freeborough and Ranken, in their treatise Chess Openings: Ancient and Modern (1889, 1896), wrote that the Sicilian "had at one time the reputation of being the best reply to 1.P-K4 [1. e4], but this has not been confirmed by popular practice. Several eminent players have, however, held to the opinion that it is quite trustworthy."

The Sicilian continued to be shunned by most leading players at the start of the twentieth century, as 1...e5 held centre stage. José Raúl Capablanca, the World Champion from 1921 to 1927, famously denounced it as an opening where "Black's game is full of holes". Similarly, James Mason wrote, "Fairly tried and found wanting, the Sicilian has now scarcely any standing as a first-class defence. ... [It] is too defensive. There are too many holes created in the Pawn line. Command of the field, especially in the centre, is too readily given over to the invading force." Siegbert Tarrasch wrote that 1...c5 "is certainly not strictly correct, for it does nothing toward development and merely attempts to render difficult the building up of a centre by the first player. ... The Sicilian Defence is excellent for a strong player who is prepared to take risks to force a win against an inferior opponent. Against best play, however, it is bound to fail." The Sicilian was not seen even once in the 75 games played at the great St. Petersburg 1914 tournament.

Nonetheless, some leading players, such as Emanuel Lasker (World Champion from 1894 to 1921), Frank Marshall, Savielly Tartakower, and Aron Nimzowitsch, and later Max Euwe (World Champion from 1935 to 1937) played the Sicilian. Even Capablanca and Tarrasch, despite their critical comments, occasionally played the opening. It was played six times (out of 110 games) at New York 1924. The following year, the authors of Modern Chess Openings (4th edition) wrote, "The Sicilian has claims to be considered as the best of the irregular defences to 1.P-K4 at Black's disposal, and has been practised with satisfactory results by the leading players of the day." In this period Black's approach was usually slow and positional, and the all-out attacks by White that became common after World War II had not yet been developed.

The fortunes of the Sicilian were further revived in the 1940s and 1950s by players such as Isaac Boleslavsky, Alexander Kotov, and Miguel Najdorf. Reuben Fine, one of the world's leading players during this time period, wrote of the Sicilian in 1948, "Black gives up control of the centre, neglects his development, and often submits to horribly cramped positions. How can it be good? Yet, the brilliant wins by White are matched by equally brilliant wins by Black; time and again the Black structure has been able to take everything and come back for more." Later, Bent Larsen, Ljubomir Ljubojević, Lev Polugaevsky, Leonid Stein, Mark Taimanov, and Mikhail Tal all made extensive contributions to the theory and practice of the defence. Through the efforts of world champions Bobby Fischer and Garry Kasparov, the Sicilian Defence became recognised as the defence that offered Black the most winning chances against 1.e4. Both players favoured sharp, aggressive play and employed the Sicilian almost exclusively throughout their careers, burnishing the defence's present reputation. Today, most leading grandmasters include the Sicilian in their opening repertoire. In 1990, the authors of Modern Chess Openings (13th edition) noted that "in the twentieth century the Sicilian has become the most played and most analysed opening at both the club and master levels." In 1965, in the tenth edition of that book, grandmaster Larry Evans observed that "The Sicilian is Black's most dynamic, asymmetrical reply to 1.P-K4. It produces the psychological and tension factors which denote the best in modern play and gives notice of a fierce fight on the very first move."

Open Sicilian: 2.Nf3 and 3.d4
About 80% of Master-level games beginning 1.e4 c5 continue with 2.Nf3, after which there are three main options for Black: 2...d6, 2...Nc6, and 2...e6. Lines where White then plays 3.d4 are collectively known as the Open Sicilian, and result in, extremely complex positions. White has a lead in development and extra kingside space, which White can use to begin a kingside attack. This is counterbalanced by Black's central pawn majority, created by the trade of White's d-pawn for Black's c-pawn, and the open c-file, which Black uses to generate queenside counterplay and even a queenside attack if White decides to castle there.

2...d6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3
Black's most common move after 2.Nf3 is 2...d6 which prepares ...Nf6 to attack the e-pawn without letting White push it to e5. The game usually continues 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3. Black can then choose between four major variations: the Najdorf (5...a6), Dragon (5...g6), Classical (5...Nc6), and Scheveningen (5...e6). The rare Kupreichik Variation (5...Bd7) may transpose to one of the more common variations such as the Classical or Dragon, but it may also lead to a number of independent lines.

There are a few ways for either side to deviate from the sequence in the heading. After 3...cxd4, White occasionally plays 4.Qxd4, the Chekhover Variation, intending to meet 4...Nc6 with 5.Bb5 Bd7 6.Bxc6, when White hopes that the lead in development compensates for Black's bishop pair. Another unusual sideline is 3...cxd4 4.Nxd4 Nf6 5.f3!?, the Prins Variation, which by delaying Nc3 maintains the option of setting up a Maróczy Bind formation with a later c2-c4. Black can avoid the Prins Variation by playing 3...Nf6, when 4.Nc3 cxd4 5.Nxd4 transposes to main lines. However, 3...Nf6 gives White an extra option in 4.dxc5!?, when Black can play either 4...Nxe4 or 4...Qa5+. White could also protect the pawn on e4 with 5.Bd3 which also allows the option of setting up a Maróczy Bind formation with a later c2-c4, or interpose a check with 5.Bb5+ Nbd7 6.Bd3 or 5.Bb5+ Bd7 6.Bxd7+ Nbxd7.

Najdorf Variation: 5...a6
The Najdorf Variation is Black's most popular system in the Sicilian Defence. Najdorf's intention with 5...a6 was to prepare ...e5 on the next move to gain space in the centre. The immediate 5...e5?! is met by 6.Bb5+!, when Black must either play 6...Bd7 or 6...Nbd7. The former allows White to exchange off Black's light-squared bishop, after which the d5-square becomes very weak; but the latter allows 7.Nf5, when Black can only save the d-pawn by playing the awkward 7...a6 8.Bxd7+ Qxd7. In both cases, White's game is preferable.

Thus, by playing 5...a6, Black deprives White of the check on b5, so that ...e5 might be possible next move. In general, 5...a6 also prevents White's knights from using the b5-square, and helps Black create queenside play by preparing the ...b5 pawn push. This plan of 5...a6 followed by ...e5 represents Black's traditional approach in the Najdorf Variation. Later, Garry Kasparov also adopted the 5...a6 move order, but with the idea of playing ...e6 rather than ...e5. Kasparov's point is that the immediate 5...e6 (the Scheveningen Variation, discussed below) allows 6.g4, which is White's most dangerous line against the Scheveningen. By playing 5...a6 first, Black temporarily prevents White's g4 thrust and waits to see what White plays instead. Often, play will eventually transpose to the Scheveningen Variation.

Currently, White's most popular weapon against the Najdorf is 6.Be3. This is called the English Attack, because it was popularized by English grandmasters Murray Chandler, John Nunn and Nigel Short in the 1980s. White's idea is to play f3, Qd2, 0-0-0 and g4 in some order. Black can respond with 6...e6, 6...e5 or 6...Ng4. A related attacking idea for White is 6.Be3 e6 7.g4, known as the Hungarian Attack or Perenyi Attack.

The most popular response from Black after 6.Be3 is 6...e5, seizing quick initiative by threatening the d4-knight. From here, the white knight has two sensible retreats: a) 7.Nb3, the more popular approach, is met with 7...Be6, and Black develops normally (...Be7, ...Nbd7, ...Rc8, ...Qc7, ...0-0, ...b5). b) 7.Nf3 is less common as it delays the possibility of a kingside pawn storm, via f4 and f3 (supporting the advance of g4). Black meets 7.Nf3 with 7...Be7 8.Bc4 0-0 9.0-0 Be6 10.Bb3 Qc7, where he has achieved a comfortable position.

Formerly, 6.Bg5 e6 7.f4 was the main line of the Najdorf, when White threatens to attack the knight with 8.e5. Black can simply break the pin with 7...Be7, when White usually plays 8.Qf3 and 9.0-0-0. Some of Black's alternatives are 7...Qb6, the Poisoned Pawn Variation popularized by Fischer, Gelfand's 7...Nbd7, and 7...b5, the Polugaevsky Variation, which has the tactical point 8.e5 dxe5 9.fxe5 Qc7! 10.exf6 Qe5+ winning the bishop in return for the knight. A modern alternative to 6...e6 is 6...Nbd7.

White has other choices on the sixth move. 6.Be2 prepares to castle kingside and is a quieter alternative compared to 6.Be3 and 6.Bg5. Efim Geller was an early proponent of this move, after which Black can stay in "pure" Najdorf territory with 6...e5 or transpose to the Scheveningen with 6...e6. Other possibilities for White include 6.Bc4 (the Fischer–Sozin Attack), 6.f4, 6.f3, 6.g3, and 6.h3 (the Adams Attack, named after Weaver Adams), which was used several times by Bobby Fischer.

Dragon Variation: 5...g6
In the Dragon Variation, Black fianchettoes a bishop on the h8–a1 diagonal. It was named by Fyodor Dus-Chotimirsky in 1901, who noticed a resemblance between Black's kingside pawn structure (pawns on d6, e7, f7, g6 and h7) and the stars of the Draco constellation. White's most dangerous try against the Dragon is the Yugoslav Attack, characterised by 6.Be3 Bg7 7.f3 0-0 8.Qd2 Nc6, when 9.0-0-0, 9.Bc4 and 9.g4 are White's most common moves. This variation leads to extremely sharp play and is ferociously complicated, since the players castle on opposite wings and the game becomes a race between White's kingside attack and Black's queenside counterattack. White's most important alternative to the Yugoslav Attack is 6.Be2, the Classical Variation of the Dragon which leads to a less ferocious game.

Classical Variation: 5...Nc6
This variation can arise from two different move orders: 1.e4 c5 2.Nf3 d6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 Nc6, or 1.e4 c5 2.Nf3 Nc6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 d6. Unlike the other major variations considered in this section, Black defers the development of the king's bishop in favour of bringing out the queen's knight.

White's most common reply is 6.Bg5, the Richter–Rauzer Attack (ECO codes B60–B69). The move 6.Bg5 was Kurt Richter's invention, threatening to double Black's pawns after Bxf6 and forestalling the Dragon by rendering 6...g6 unplayable. After 6...e6, Vsevolod Rauzer introduced the modern plan of Qd2 and 0-0-0 in the 1930s. White's pressure on the d6-pawn often compels Black to respond to Bxf6 with ...gxf6, rather than recapturing with a piece (e.g. the queen on d8) that also has to defend the d-pawn. This weakens Black's kingside pawn structure, but in return Black gains the two bishops and a central pawn majority.

Another variation is 6.Bc4, the Sozin Variation (ECO code B57). It brings the bishop to an aggressive square. Black usually plays 6...e6 (ECO B88 transposed) to limit the range of White's bishop, but White can eventually put pressure on the e6-pawn by pushing the f-pawn to f5 (pawn-based attack beginning with f4). White can either castle kingside with 7.Bb3 a6 8.0-0 (the Fischer–Sozin Attack, named after Bobby Fischer and Russian master Veniamin Sozin, who originated it in the 1930s), or queenside with 7.Be3 Be7 (or 7...a6) 8.Qe2 and 9.0-0-0 (the Velimirović Attack). Instead of 6...e6, Black can also try Benko's move 6...Qb6, which forces White to make a decision over the d4-knight. This typically leads into more positional lines than the razor-sharp, highly theoretical Sozin and Velimirović variations.

White's third most common move is 6.Be2, (ECO codes B58–B59), after which Black can remain in independent variations with the Boleslavsky Variation 6...e5, named after Isaac Boleslavsky. The old main line 7.Nb3 is now less popular than the modern 7.Nf3, after which the game usually continues 7...h6 8.0-0 Be7 9.Re1 0-0 10.h3. Black can also transpose to the Scheveningen Variation with 6...e6; or to the Classical Variation of the Dragon with 6...g6. Other responses by White to the Classical include 6.Be3, 6.f3, and 6.g3.

Scheveningen Variation: 5...e6
In the Scheveningen Variation, Black is content to place the e-pawn on e6, where it guards the d5-square, rather than play the space-gaining ...e5. Moving the e-pawn also prepares ...Be7 followed by kingside castling. In view of this, Paul Keres introduced 6.g4, the Keres Attack, in 1943. White intends to drive away the black knight with g5. If Black prevents this with 6...h6, which is the most common answer, White has gained kingside space and discouraged Black from castling on that side, and may later play Bg2. If the complications after 6.g4 are not to White's taste, a major alternative is 6.Be2, a typical line being 6...a6 (this position can be reached from the Najdorf via 5...a6 6.Be2 e6) 7.0-0 Be7 8.f4 0-0. 6.Be3 and 6.f4 are also common.

While theory indicates that Black can hold the balance in the Keres Attack, players today often prefer to avoid it by playing 5...a6 first, an idea popularized by Kasparov. However, if determined to play the g4 thrust, White can prepare it by responding to 5...a6 with 6.h3 or 6.Rg1.

2...Nc6 3.d4 cxd4 4.Nxd4
2...Nc6 is a natural developing move and also prepares ...Nf6 (like 2...d6, Black stops White from replying e5). After 3.d4 cxd4 4.Nxd4, Black's most common move is 4...Nf6. Other important moves are 4...e6 (transposing to the Taimanov Variation), 4...g6 (the Accelerated Dragon) and 4...e5 (the Kalashnikov Variation). Less common choices include 4...Qc7, which may later transpose to the Taimanov Variation, 4...Qb6, the Grivas Variation, and 4...d6.

After 4...Nf6, White usually replies 5.Nc3. Black can play 5...d6, transposing to the Classical Variation; 5...e5, the Sveshnikov Variation; or 5...e6, transposing to the Four Knights Variation.

Sveshnikov Variation: 4...Nf6 5.Nc3 e5
The Sveshnikov Variation was pioneered by Evgeny Sveshnikov and in the 1970s. Before their efforts, the variation was called the Lasker–Pelikan Variation. Emanuel Lasker played it once in his world championship match against Carl Schlechter, and Jorge Pelikan played it a few times in the 1950s, but Sveshnikov's treatment of the variation was the key to its revitalization. The move 5...e5 seems anti-positional as it leaves Black with a backwards d-pawn and a weakness on d5. Also, Black would have to accept the doubled f-pawns in the main line of the opening. The opening was popularised when Sveshnikov saw its dynamic potential for Black in the 1970s and 80s. Today, it is extremely popular among grandmasters and amateurs alike. Though some lines still give Black trouble, it has been established as a first-rate defence. The main line after 5...e5 runs as follows:

6. Ndb5
 * The theoretically critical move, threatening Nd6+. All other moves are considered to allow Black easy equality. 6.Nxc6?! is usually met by 6...bxc6, when Black's extra pawn in the centre gives good play; alternatively, even 6...dxc6 7.Qxd8+ Kxd8 is sufficient for equality. 6.Nb3 and 6.Nf3 can be well met by 6...Bb4, threatening to win White's pawn on e4. 6.Nf5 allows 6...d5! 7.exd5 Bxf5 8.dxc6 bxc6 9.Qf3 Qd7. 6.Nde2 can be met by either 6...Bc5 or 6...Bb4.

6...d6
 * Black does not allow 7.Nd6+ Bxd6 8.Qxd6, when White's pair of bishops give them the advantage.

7. Bg5
 * White gets ready to eliminate the knight on f6, further weakening Black's control over the d5-square. A less common alternative is 7.Nd5 Nxd5 8.exd5 Nb8 (or 8...Ne7), when White will try to exploit the queenside pawn majority, while Black will seek counterplay on the kingside.

7...a6
 * Black forces White's knight back to a3.

8. Na3
 * The immediate 8.Bxf6 forces 8...gxf6, when after 9.Na3, Black can transpose into the main line with 9...b5 or deviate with 9...f5!?

8...b5!
 * 8...b5 was Sveshnikov's innovation, controlling c4 and threatening ...b4 forking White's knights. Previously, Black played 8...Be6 (the Bird Variation), which allowed the a3-knight to return to life with 9.Nc4. The entire variation up to 8...b5 is referred to as the Chelyabinsk Variation. It can also be reached from the alternate move order 1.e4 c5 2.Nf3 e6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 Nc6 6.Ndb5 d6 7.Bf4 e5 8.Bg5 a6 9.Na3 b5, which is one move longer. (That alternative move order gives White other alternatives, including 6.Nxc6 bxc6 7.e5 Nd5 8.Ne4, intending c4, and the gambit 6.Be2 Bb4 7.0-0!?, allowing ...Bxc3 8.bxc3 Nxe4.) The move numbers in the following discussion are based on the move order given in bold.

The Sveshnikov Variation has become very popular in master level chess. Black's ...e5 push seems anti-positional: it has made the d6-pawn backward and the d5-square weak. However, in return, Black gets a foothold in the centre and gains time on White's knight, which has been driven to the edge of the board on a3. Top players who have used this variation include Magnus Carlsen, Vladimir Kramnik, Veselin Topalov, Teimour Radjabov, Boris Gelfand, Michael Adams and Alexander Khalifman, among many others.

In the diagrammed position after 8...b5, White usually parries the threat of ...b4 by playing 9.Bxf6 or 9.Nd5. After 9.Bxf6, 9...Qxf6?! 10.Nd5 Qd8 fails to 11.c4 b4 (11...bxc4 12.Nxc4 is good for White, who threatens 13.Qa4) 12.Qa4 Bd7 13.Nb5! axb5 14.Qxa8 Qxa8 15.Nc7+ Kd8 16.Nxa8 and the knight escapes via b6. Thus 9...gxf6 is forced, and White continues 10.Nd5. White's powerful knight on d5 and Black's shattered kingside pawn structure are compensated by Black's bishop pair and White's offside knight on a3. Also, Black has the plan of playing 10...f5, followed by ...fxe4 and ...f5 with the second f-pawn, which would give them good control of the centre. An alternative plan is to play 10...Bg7 followed by ...Ne7 to immediately trade off White's powerful knight; this line is known as the Novosibirsk Variation.

Instead of 9.Bxf6, White can also play 9.Nd5, which usually leads to quieter play. White decides not to double Black's f-pawns and the game often continues 9...Be7 10.Bxf6 Bxf6 11.c3. This allows White to maintain the knight on d5 by trading off Black's knight on f6, and prepares to bring the knight on a3 back into play with the manoeuvre Na3–c2–e3. Another line is 10.Nxe7 Nxe7! (fighting for control of d5 and not fearing the doubled pawns) 11.Bxf6 gxf6. However, a recent development in the Sveshnikov has been 11.c4 (instead of c3), which often leads to positions where White is pressing for the win at no risk. A quick draw is possible after 9.Nd5 Qa5+!? 10.Bd2 (in order to prevent 10...Nxe4) 10...Qd8 11.Bg5 Qa5+ etc. In order to avoid this, White can play 11.Nxf6+ or 11.c4.

Accelerated Dragon: 4...g6
Like the standard Dragon Variation, Black develops the bishop to g7 in the Accelerated Dragon. The difference is that Black avoids playing ...d7–d6 and can later play ...d7–d5 in one move if possible. For example, if White tries to play in the style of the Yugoslav Attack with 5.Nc3 Bg7 6.Be3 Nf6 7.f3 0-0 8.Qd2, 8...d5! equalises immediately. When White does play 5.Nc3, it is usually with the idea of continuing 5...Bg7 6.Be3 Nf6 7.Bc4 0-0 8.Bb3 (forestalling any tricks involving ...Nxe4 and ...d5), followed by kingside castling.

The critical test of Black's move order is 5.c4, the Maróczy Bind. White hopes to cramp Black's position by impeding the ...d7–d5 and ...b7–b5 pawn thrusts. Generally, this line is less tactical than many of the other Sicilian variations, and play involves much strategic maneuvering on both sides. After 5.c4, the main line runs 5...Bg7 6.Be3 Nf6 7.Nc3 and now 7...0-0 or 7...Ng4 is most frequently played.

Kalashnikov Variation: 4...e5 5.Nb5 d6
The Kalashnikov Variation (ECO code B32) is a close relative of the Sveshnikov Variation, and is sometimes known as the Neo-Sveshnikov. The move 4...e5 has had a long history; Louis-Charles Mahé de La Bourdonnais used it in his matches against Alexander McDonnell in 1834, and it was also popular for a short time in the 1940s. These earlier games focused on the Löwenthal Variation (similar to the Kalashnikov but the reply to 5.Nb5 is 5...a6) with 4...e5 5.Nb5 a6 6.Nd6+ Bxd6 7.Qxd6 Qf6, where Black gives up the two bishops to achieve a lead in development. The move fell out of use, however, once it was determined that White kept the advantage in these lines. Another fifth move alternative for Black is 5...Nf6, which can transpose into the Sveshnikov Variation after 6.N1c3 or 6.Bg5 d6 7.N1c3.

Only in the late 1980s did Black players revive 4...e5 with the intention of meeting 5.Nb5 with 5...d6: this is the Kalashnikov Variation. The ideas in this line are similar to those in the Sveshnikov – Black accepts a backward pawn on d6 and weakens the d5-square but gains time by chasing the knight. The difference between the two variations is that Black has not developed the knight to f6 and White has not brought the knight to c3, so both players have extra options. Black may forego ...Nf6 in favour of ...Ne7, e.g. after 6.N1c3 a6 7.Na3 b5 8.Nd5 Nge7, which avoids White's plan of Bg5 and Bxf6 to inflict doubled f-pawns on Black. Or, Black can delay bringing out the knight in favour of playing ...Be7–g5 or a quick ...f5. On the other hand, White has the option of 6.c4—the Maróczy Bind—which solidifies control of d5 and clamps down on ...b5, but leaves the d4-square slightly weak.

2...e6 3.d4 cxd4 4.Nxd4
Black's move 2...e6 gives priority to developing the dark-squared bishop. After 3.d4 cxd4 4.Nxd4, Black has three main moves: 4...Nc6 (the Taimanov Variation), 4...a6 (the Kan Variation) and 4...Nf6. After 4...Nf6 5.Nc3 (not 5.e5? Qa5+), Black can transpose to the Scheveningen Variation with 5...d6, play 5...Nc6, the Four Knights Variation or 5...Bb4, the Pin Variation.

Taimanov Variation: 4...Nc6
Named after Mark Taimanov, the Taimanov Variation can be reached through 2...e6 3.d4 cxd4 4.Nxd4 Nc6 or 2...Nc6 3.d4 cxd4 4.Nxd4 e6. Black develops the knight to a natural square and keeps options open regarding the placement of the other pieces. One of the ideas of this system is to develop the king's bishop to b4 or c5. White can prevent this by 5.Nb5 d6, when 6.c4 leads to a version of the Maróczy Bind favoured by Karpov. The resulting position after 6.c4 Nf6 7.N1c3 a6 8.Na3 b6 is a type of Hedgehog.

The Kasparov Gambit 8...d5 was played twice in the World Chess Championship 1985, but virtually disappeared from master praxis after the game Karpov–Van der Wiel, Brussels (SWIFT) 1986.

5.Nc3 is more common nowadays than 5.Nb5, when 5...d6 normally transposes to the Scheveningen Variation and 5...Nf6 is the Four Knights Variation (see below). Independent moves for Black are 5...Qc7 and 5...a6, with the former being the more usual move order seen in recent years, as after 5...a6, the continuation 6.Nxc6 bxc6 7.Bd3, despite its apparent simplicity, has given Black difficulties in reaching equality. Taimanov's idea was to play 5...a6 (preventing Nb5) followed by ...Nge7 and ...Nxd4; however, the modern treatment of the line is to play ...Nf6, for example 5.Nc3 Qc7 6.Be2 a6 7.Be3 Nf6.

Kan (Paulsen) Variation: 4...a6
Named after Ilya Kan. By playing 4...a6, Black prevents Nb5 and prepares an eventual ...b5 advance.

The most popular fifth move for White is 5.Bd3, when after 5...Bc5 6.Nb3 Black can either retreat 6...Be7 where 7.Qg4 makes Black's kingside problematic, or 6...Ba7. Also possible is 5.c4 to create a Maróczy Bind setup.

White's second most popular reply is 5.Nc3, when Black's development of the kingside knight often takes focus, since playing ...Nf6 can be met with e5 which both creates a Black weakness on the d6-square and causes the Black knight a disadvantageous move. So Black normally plays a move to control the e5-square and prevent the pawn from advancing. The main Kan move is 5...Qc7, although 5...Nc6 transposing into a Taimanov or 5...d6 transposing into a Scheveningen can occur. An alternative idea is the immediate 5...b5 to create pressure from the queenside with the idea of playing ...b4 attacking the c3-knight, or ...Bb7 to build pressure along the long white-squared diagonal. White generally answers with 6.Bd3, supporting the e4-pawn.

Four Knights Variation: 4...Nf6 5.Nc3 Nc6
The Four Knights Variation is mainly used as a way of getting into the main line Sveshnikov Variation, reached after 6.Ndb5 d6 7.Bf4 e5 8.Bg5 a6 9.Na3 b5 or 6.Bf4 d6 7.Ndb5 e5 8.Bg5 a6 9.Na3 b5. The point of this move order is to avoid lines such as the Rossolimo Variation (1.e4 c5 2.Nf3 Nc6 3.Bb5), or 1.e4 c5 2.Nf3 Nc6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 e5 6.Ndb5 d6 7.Nd5, which are possible in the standard Sveshnikov move order. On the other hand, in the Four Knights move order, White acquires the extra option of 6.Nxc6 bxc6 7.e5 Nd5 8.Ne4, so White is not obliged to enter the Sveshnikov.

If Black is not aiming for the Sveshnikov, the main alternative is to play 6...Bb4 in reply to 6.Ndb5. Then 7.a3 Bxc3+ 8.Nxc3 d5 9.exd5 exd5 leads to a position where Black has given up the two bishops but has active pieces and the possibility of playing ...d5–d4.

Pin Variation: 4...Nf6 5.Nc3 Bb4
The Pin Variation (also called the Sicilian Counter-Attack) is considered theoretically suspect, but if White is unprepared the tactics can be difficult to calculate at the board. After 6.e5! (6.Bd3 is less challenging) Black has:
 * 6...Ne4?! 7.Qg4! Nxc3 8.Qxg7 Rf8 9.a3 Nb5+ 10.axb4 Nxd4 11.Bg5 Qb6 12.Bh6 Qxb4+ 13.c3 Nf5 14.cxb4 Nxg7 15.Bxg7 with a clear advantage to White, Szabo-Mikenas, Kemeri 1939
 * 6...Nd5 7.Bd2 Nxc3 8.bxc3 Be7 9.Qg4 and Black must either weaken the kingside with 9 ... g6 or give up the exchange after 9 ... 0-0 10.Bh6 g6. White need not take the exchange, and attacking with 11.h4 may in fact be stronger.

Also intriguing is 6. Nb5!, with 6...Nxe4?! met with 7. Qg4, with strong compensation for the pawn.

2.Nf3 without 3.d4: White's third move alternatives
White can play 2.Nf3 without intending to follow up with 3.d4. The systems given below are usually classified along with White's second move alternatives as.

Moscow Variation: 3.Bb5+
After 1.e4 c5 2.Nf3 d6, White's most important alternative to 3.d4 is 3.Bb5+, known as the Moscow Variation or Canal–Sokolsky Attack. Grandmasters sometimes choose this variation when they wish to avoid theory; for instance, it was played by Garry Kasparov in the online game Kasparov–The World. Experts in this line include GMs Sergei Rublevsky and Tomáš Oral. Former World Champion Magnus Carlsen has also played this variation extensively. Black can block the check with 3...Bd7, 3...Nc6 or 3...Nd7. The position after 3...Nc6 can also be reached via the Rossolimo Variation after 1.e4 c5 2.Nf3 Nc6 3.Bb5 d6.

Most common is 3...Bd7, when after 4.Bxd7+ Qxd7, White can either play 5.0-0 followed by c3 and d4, or 5.c4 in the style of the Maróczy Bind.

Others
Another possibility for White is 3.c3, a delayed variation of the Sicilian Defence, Alapin Variation intending to establish a pawn centre with d4 next move. The most frequent continuation is 3...Nf6 4.Be2, when 4...Nxe4? loses to 5.Qa4+ and likewise 4...Nc6 5 d4 Nxe4? loses to 6 d5 and 7 Qa4+

Rossolimo Variation: 3.Bb5
The Rossolimo Variation, 3.Bb5, is a well-respected alternative to 3.d4. It is named after Nicolas Rossolimo and is related to the Moscow Variation. White's usual intention is to play Bxc6, giving Black doubled pawns. Black's major responses are 3...g6 preparing ...Bg7, 3...d6 preparing ...Bd7 (a hybrid line that also arises from the Moscow Variation after 2...d6 3.Bb5+ Nc6), and 3...e6 preparing 4...Nge7. Sergei Rublevsky and Tomáš Oral both play this line as well as the Moscow Variation. The Italian American Grandmaster Fabiano Caruana is perhaps the biggest proponent of this line at the top level, and has played this variation in Games 1, 3 and 5 of his World Championship Match against Magnus Carlsen.

Others
3.Nc3 is a common transpositional device for White, who can play 4.d4 or 4.Bb5 next move depending on Black's response. Black sometimes plays 3...e5 to avoid both moves; then 4.Bc4 is considered White's best move. 3.c3 transposes to lines of the Alapin Variation after 3...Nf6 or 3...d5, while 3.c4 transposes into the Symmetrical English.

2...e6 without 3.d4
White sometimes plays 3.Nc3 as a waiting move, though it has little independent significance. With 3.d3, White plans to develop in King's Indian Attack style with g3 and Bg2; this line was used by Fischer to crush Oscar Panno in a famous game (Fischer–Panno, Buenos Aires 1970). 3.c3 will transpose to lines of the Alapin Variation after 3...Nf6, or the French Defence after 3...d5 4.e5 Nc6 5.d4, though 4...d4 is stronger, as after 5.cxd4 cxd4 6.Qa4+ Nc6 7.Bb5 Bd7 8.Bxc6 Bxc6 9.Qxd4 Bxf3 is a strong pawn sacrifice, giving Black excellent compensation. 3.c4 transposes into the Symmetrical English. 3.b3, intending Bb2, is a rare independent try, occasionally essayed by Heikki Westerinen in the 1970s.

3.Bd3
Danny Kopec has suggested the move 3.Bd3 against any of Black's common responses, intending to follow up with c3 and Bc2.

2.Nf3: Black's second move alternatives
After 1.e4 c5 2.Nf3, Black has some less commonly played options apart from 2...d6, 2...Nc6 and 2...e6.

Hyper-Accelerated Dragon: 2...g6
After 2...g6, White commonly plays 3.d4, which may transpose to the Accelerated Dragon after 3...cxd4 4.Nxd4 Nc6, although White may deviate by playing 4.Qxd4, and Black can also avoid the transposition with 3.d4 Bg7 4.dxc5 Qa5+. Other third move options for White are 3.c3 transposing to a variation of the Alapin, and 3.c4 (Maróczy Bind).

O'Kelly Variation: 2...a6
2...a6 is the O'Kelly Variation. Black's idea is to meet 3.d4 with 3...cxd4 4.Nxd4 Nf6 5.Nc3 e5 when 6.Ndb5 is prevented, and after 6.Nb3 or 6.Nf3 Black will equalize by playing 6...Bb4 and possibly ...d5. However, White may avoid this by instead playing 3.c3 or 3.c4.

Nimzowitsch–Rubinstein Variation: 2...Nf6
2...Nf6 is the Nimzowitsch Variation. It bears some similarity to Alekhine's Defence. White's strongest reply is to chase the knight by 3.e5 Nd5 4.Nc3 and now (a) 4...Nxc3 5.dxc3, when 5...b6?, as Nimzowitsch played and recommended, loses to 6.e6! f6 7.Ne5! or (b) 4...e6 (the main line) 5.Nxd5 exd5 6.d4 Nc6 7.dxc5 Bxc5 8.Qxd5 Qb6 (8...d6 9.exd6 Qb6 is also played) 9.Bc4! Bxf2+ 10.Ke2 0-0 11.Rf1 Bc5 12.Ng5 Nd4+ 13.Kd1 with sharp play favouring White.

Others
Other moves include:
 * 2...b6 is the Katalymov Variation, after the Kazakh/Russian master Boris Katalymov. It is generally considered better for White, though it has frequently been played by the French GM Christian Bauer. Other GMs, including Gata Kamsky, have occasionally used it as a surprise weapon.
 * 2...Qc7 is the Quinteros Variation. It will frequently transpose into a standard line such as the Taimanov Variation or Kan Variation, or else White can play 3.c3 in the style of the Alapin Variation, where Black's queen may not be so well placed on c7.

Closed Sicilian: 2.Nc3
2.Nc3 is White's second most common move responding to 1.e4 c5. Black's options are similar to those for 2.Nf3, the most common being ...Nc6, along with ...e6 and ...d6, and less commonly ...a6 and ...g6. 2...e5 transposes into a variant of the Vienna Game. In all cases, White can then play 3.Nf3, as if White had played 2.Nf3 then 3.Nc3 (e.g. 2.Nf3 Nc6 3.Nc3 (ECO code B30)).

For the most part, other moves are the Closed Sicilian. Possible moves are 3.g3 and 3.f4 in general, also 3.Nge2, and less commonly 3.d3 and 3.Bc4. Many lines transpose to the Open Sicilian, the Moscow Variation, or the Rossolimo Variation, but there are many that do not.

Also of some interest is 3.Bb5 to ...Nc6.

A typical line is 2...Nc6 3.g3 (ECO code B24). Also, 2...Nc6 3.f4 is the Closed Sicilian, Grand Prix Attack (part of B23).

White can also keep options open with 3.Nge2. Andrew Soltis has dubbed that the "Chameleon System", since White maintains the option of playing a Closed Sicilian with 4.g3 or transposing to a standard Open Sicilian with 4.d4 cxd4 5.Nxd4. Two drawbacks are that (a) the Closed Sicilian lines with an early Nge2 are not very challenging for Black, and (b) if Black plays 2...Nc6 3.Nge2 g6, 4.d4 reaches an Accelerated Dragon where White has lost the option of playing c4, the Maróczy Bind, often considered White's best line. In view of possible transpositions to the main Sicilian variations, Black has various replies to 2.Nc3 in the Open Sicilian. 2...Nc6 is the most common choice, but 2...e6 and 2...d6 are often played. The Main line of the Closed Sicilian is 2.Nc3 Nc6 3.g3 g6 4.Bg2 Bg7 5.d3 d6 (diagram), when White's main options are 6.Be3 followed by Qd2 and possibly 0-0-0, and 6.f4 followed by Nf3 and 0-0.

White's second move alternatives
After 1.e4 c5, other moves besides 2.Nf3 and 2.Nc3 are popular.

Alapin Variation: 2.c3
2.c3 is the Alapin Variation or c3 Sicilian. Originally championed by Semyon Alapin at the end of the 19th century, it was revived in the late 1960s by Evgeny Sveshnikov and Evgeny Vasiukov. Nowadays its strongest practitioners include grandmasters Sergei Tiviakov and Eduardas Rozentalis.

White aims to set up a classical pawn centre with 3.d4, so Black should counter immediately in the centre by 2...Nf6 or 2...d5.

The line 2...Nf6 3.e5 Nd5 resembles Alekhine's Defence, but the inclusion of the moves c3 and ...c5 is definitely in Black's favour. Now White can play 4.d4 cxd4 5.Nf3, when Black has a choice between 5...e6 and 5...Nc6. Another idea for White is 5.Bc4, which is met by 5...Qc7.

The other main line is 2...d5 3.exd5 Qxd5 4.d4 Nf6 5.Nf3, when Black's main options are 5...e6 and 5...Bg4. In this line, White usually ends up with an isolated queen's pawn after pawns are exchanged on d4.

A rarer option on Black's second move is 2...e6, with the aim of transposing to the Advance Variation of the French Defence after 3.d4 d5 4.e5.

Grand Prix Attack: 2.f4
2.f4 is the Grand Prix Attack or McDonnell Attack: the latter name stems from the 14th match game played in London in 1834 between Alexander McDonnell and Charles Louis Mahé de La Bourdonnais, won by Black. According to Jeremy Silman and others, Black's best reply is 2...d5 3.exd5 Nf6!, the Tal Gambit, which has caused the immediate 2.f4 to decline in popularity. White may decline the gambit with 3.Nc3, called the "Toilet Variation", so named after its reputed place of invention. A less common option is 2...e6, as La Bourdonnais played against McDonnell. Players usually enter the Grand Prix Attack nowadays by playing 2.Nc3 first before continuing 3.f4. The modern main line runs 2.Nc3 Nc6 3.f4 g6 4.Nf3 Bg7. Here White can play the positional 5.Bb5, threatening to double Black's pawns with Bxc6, or the more aggressive 5.Bc4, aiming for a kingside attack.

Smith–Morra Gambit: 2.d4 cxd4 3.c3
2.d4 cxd4 3.c3 is the Smith–Morra Gambit. Declining it by either 3...Nf6 or 3...d5, transposing to the c3 line, is possible, but accepting it by 3...dxc3 is critical. After 4.Nxc3, White is considered not to have enough compensation for the pawn;   however, it can be dangerous for Black if they are unprepared, as there are many pitfalls for the unwary.

Other moves
Other reasonable moves include:
 * 2.Ne2 is the Keres Variation, a favourite of Paul Keres, and has similar ideas to the Chameleon System discussed under 2.Nc3 – White can follow up with 3.d4 with an Open Sicilian, 3.g3 with a Closed Sicilian, or 3.Nbc3, continuing to defer the choice between the two.
 * 2.g3 is known as the Lasker–Dunne Attack. It was played between Steinitz and Anderssen in their 1866 match. It was also sometimes played by Taimanov. It can transpose to the Closed Sicilian but offers other options such as 2...d5 3.exd5 Qxd5, with Black's queen threatening to capture White's exposed rook, and an incipient central buildup with c3 and d4 for White.
 * 2.c4 occasionally leads to positions that resemble lines in the English Opening. Palliser and Keres recommend avoiding mainline English theory with 2...Nc6 3.Nc3 e5!, which prevents White from playing d4.
 * 2.d3 signals White's intention to develop along King's Indian Attack lines, and usually transposes to the Closed Sicilian.
 * 2.e5, which gains space and prevents Black playing ...Nf6. White often supports the e5-pawn with 3.f4 or 3.Nf3. The drawback of 2.e5 is that no additional pressure is brought to the centre, allowing Black various options.
 * 2.Na3 is an eccentric move recently returned to prominence by GM Vadim Zvjaginsev at the 2005 Russian Chess Championship Superfinal. He used it three times during the tournament, drawing twice and beating Alexander Khalifman.
 * 2.Qh5, threatening the c-pawn as in the Wayward Queen Attack, was played twice in 2005 by Hikaru Nakamura, but the move is considered dubious. Simply 2...Nf6 gives Black a comfortable position after 3.Qxc5 Nxe4, while 3.Qh4 displaces the queen and loses time. Nakamura lost in 23 moves to Andrei Volokitin in 2005, and Neil McDonald criticised the opening experiment as "rather foolish".
 * 2.a3, the Mengarini Variation, is similar to the Wing Gambit, the idea being to play 3.b4 next move.
 * 2.b3 followed by 3.Bb2 is the Snyder Variation, named for USCF master Robert M. Snyder. It has been used occasionally by Nigel Short and is a favourite of Georgian GM Tamaz Gelashvili.
 * 2.Bc4 is the Bowdler Attack, and though once played at the highest level, is popular today only among club players or beginners who are unfamiliar with the Sicilian and are looking either to attack the weak f7 pawn or to prepare for a quick kingside castle. However, after a move such as 2...e6, Black will soon play ...d5 and open up the centre while gaining time by attacking the bishop. Anderssen–Wyvill, London 1851, continued 2...e6 3.Nc3 a6 4.a4 Nc6 5.d3 g6 6.Nge2 Bg7 7.0-0 Nge7 8.f4 0-0 9.Bd2 d5 10.Bb3 Nd4 11.Nxd4, and now Soltis recommends 11...cxd4! 12.Ne2 Bd7!
 * 2.b4 is the Wing Gambit. White's idea is 2.b4 cxb4 3.a3, hoping to deflect Black's c-pawn, then dominate the centre with an early d4. However, chess theory has proven in the past that this idea is dubious at best. The Wing Gambit is thus generally considered too reckless, and rarely seen in grandmaster praxis. GM Joe Gallagher calls it "a forgotten relic, hardly having set foot in a tournament hall since the days of Frank Marshall and Rudolph Spielmann. White sacrifices a pawn for ... well, not a lot."

ECO codes
The Encyclopaedia of Chess Openings classifies the Sicilian Defence under the codes B20 through B99, giving it more codes than any other opening. In general these guidelines apply:
 * Codes B20 through B29 cover lines after 1.e4 c5 where White does not play 2.Nf3, and lines where White plays 2.Nf3 and Black responds with a move other than 2...d6, 2...Nc6 or 2...e6.
 * Codes B30 through B39 cover the lines beginning 1.e4 c5 2.Nf3 Nc6 that do not transpose into lines that can also begin with 2...d6. The most important variations included here are the Rossolimo, Kalashnikov, Sveshnikov and Accelerated Dragon.
 * Codes B40 through B49 cover the lines beginning 1.e4 c5 2.Nf3 e6, most importantly the Taimanov and Kan variations.
 * Codes B50 through B59 cover the lines after 1.e4 c5 2.Nf3 d6 not covered in codes B60–B99. This includes the Moscow Variation (3.Bb5+), 3.d4 cxd4 4.Qxd4, and lines in the Classical Variation except for the Richter–Rauzer Attack, including the Sozin Attack and the Boleslavsky Variation.
 * Codes B60 through B69 cover the Richter–Rauzer Attack of the Classical Variation.
 * Codes B70 through B79 cover the normal (unaccelerated) Dragon Variation.
 * Codes B80 through B89 cover the Scheveningen Variation.
 * Codes B90 through B99 cover the Najdorf Variation.

title: Sicilian Defence


text:
Kyushu J7W Shinden

The Kyūshū J7W Shinden (震電, "Magnificent Lightning") is a World War II Japanese propeller-driven prototype fighter plane with wings at the rear of the fuselage, a nose-mounted canard, and a pusher engine.

Developed by the Imperial Japanese Navy (IJN) as a short-range, land-based interceptor, the J7W was a response to Boeing B-29 Superfortress raids on the Japanese home islands. For interception missions, the J7W was to be armed with four forward-firing 30 mm type 5 cannons in the nose.

The Shinden was expected to be a highly maneuverable interceptor, but only two prototypes were finished before the end of the war. A jet engine–powered version was considered, but never reached the drawing board.

Design and development
In the IJN designation system, "J" referred to land-based fighters and "W" to Watanabe Tekkōjo, the company that oversaw the initial design.

The idea of a canard-based design originated with Lieutenant Commander Masayoshi Tsuruno, of the technical staff of the IJN in early 1943. Tsuruno believed the design could easily be retrofitted with a turbojet, when suitable engines became available. His ideas were worked out by the First Naval Air Technical Arsenal (Dai-Ichi Kaigun Koku Gijitsusho), which designed three gliders designated Yokosuka MXY6, featuring canards. These were built by Chigasaki Seizo K. K. and one was later fitted with a 22 hp Semi 11 (Ha-90) 4-cylinder air-cooled engine.

The feasibility of the canard design was proven by both the powered and unpowered versions of the MXY6 by the end of 1943, and the Navy were so impressed by the flight testing, they instructed the Kyushu Aircraft Company to design a canard interceptor around Tsuruno's concept. Kyushu was chosen because both its design team and production facilities were relatively unburdened, and Tsuruno was chosen to lead a team from Dai-Ichi Kaigun Koku Gijitsusho to aid Kyushu's design works.

The construction of the first two prototypes started in earnest by June 1944, stress calculations were finished by January 1945, and the first prototype was completed in April 1945. The 2,130 hp Mitsubishi MK9D (Ha-43) radial engine and its supercharger were installed behind the cockpit and drove a six-bladed propeller via an extension shaft. Engine cooling was to be provided by long, narrow, obliquely mounted intakes on the side of the fuselage. It was this configuration that caused cooling problems while running the engine while it was still on the ground. This, together with the unavailability of some equipment parts postponed the first flight of the Shinden.

Even before the first prototype took to the air, the Navy ordered the J7W1 into production, with a quota of 30 Shinden a month given to Kyushu's Zasshonokuma factory and 120 from Nakajima's Handa plant. It was estimated some 1,086 Shinden could be produced between April 1946 and March 1947.

On 3 August 1945, the prototype first flew, with Tsuruno at the controls, from Mushiroda Airfield. Two more short flights were made, a total of 45 minutes airborne, one each on the same days as the atomic bombings of Hiroshima and Nagasaki occurred, before the war's end. Flights were successful, but showed a marked torque pull to starboard (due to the powerful engine), some flutter of the propeller blades, and vibration in the extended drive shaft.

Surviving aircraft

The two prototypes were the only examples of the Shinden ever completed. After the end of the war, one was scrapped; the other was claimed by a U.S. Navy Technical Air Intelligence Unit in late 1945, dismantled, and shipped to the United States.

The sole surviving J7W1 was reassembled, but has never been flown in the United States; the USN transferred it to the Smithsonian Institution in 1960. Its forward fuselage is currently on display at the Steven F. Udvar-Hazy Center annex (at Dulles Airport) of the National Air and Space Museum in Washington DC. According to the NASM, 'miscellaneous parts' are stored at Building 7C at the older storage/annex facility, the Garber Facility in Suitland, Maryland. A replica of the J7W1, built by a then-unknown production company, was unveiled at the Tachiarai Peace Memorial Museum in July 2022. The company was later revealed to be Toho Studios with the replica being made for the production of Godzilla Minus One (2023).

In popular culture
The plane was featured in Godzilla Minus One, where it was used against the titular monster.

A modified version of the plane, designated the Sanka Mk.B, was featured heavily in the film The Sky Crawlers.

The Shinden was also featured in Ted Nomura's six issue Kamikaze: 1946 comic of 2000/2001

title: Kyushu J7W Shinden


text:
Talk:European System of Central Banks

I don't really see why all that copyright notice stuff is needed. ECB doesn't require it, and the article was properly sourced as it was. --Vikingstad 23:28, 1 Mar 2004 (UTC)

mumbo jumbo
I took off the irrelevant copyright notice (from the ECB). It's clear that Wikipedia was not violating the ECB copyright conditions.

However, it is clear that this article was primarily written by central bankers or Eurocrats who don't know how to write clearly. It contradicts itself e.g. 1st and 3rd sentences. Let's try to clean this up more and put it in plain English. Smallbones 11:41, 21 April 2006 (UTC)

Eurosystem
Why are the objectives of the Eurosystem mentioned in this article and not the objectives of the European System of Central Banks itself? It is odd that the objectives of the ESCB are mentioned in the article Eurosystem but not here. --PJ Geest (talk) 16:47, 30 July 2009 (UTC)

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title: Talk:European System of Central Banks