For the Chigorin Variation of the Ruy Lopez, see Ruy Lopez § Chigorin Variation.
Chess opening
Chigorin Defense
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Moves
1.d4 d5 2.c4 Nc6
ECO
D07
Named after
Mikhail Chigorin
Parent
Queen's Gambit
The Chigorin Defense is a chess opening named for 19th century Russian grandmaster Mikhail Chigorin. An uncommonly played defense to the Queen's Gambit, it begins with the moves:
1. d4 d5
2. c4 Nc6
The Chigorin Defense violates several classical principles: Black does not maintain the center pawn at d5, the c-pawn is blocked, and Black must be willing to trade a bishop for a knight. In return Black gets quick development and piece pressure on the center.
Although opening assessments change as improvements are found for each side, the Chigorin is generally considered playable for Black and it is useful as a surprise weapon against the Queen's Gambit. Alexander Morozevich is perhaps the only modern grandmaster who regularly plays the Chigorin Defense, although in the 1980s, Vasily Smyslov did employ the opening against Garry Kasparov. Morozevich has also published a book on the Chigorin Defence,[1] in which he gives both a theoretical and a personal view on the opening.
This article uses algebraic notation to describe chess moves.
Main variations
The Chigorin Defense has the ECO classification D07.
Because the Chigorin is an unusual defense, the theory of this opening is not as well developed as that for more popular openings.
After 1.d4 d5 2.c4 Nc6 some of the most commonly played variations are:
3...dxc4 4.Nf3 Nf6 5.e4 Bg4 6.Be3 e6 7.Bxc4 Bb4 is a position that occurs very frequently in current practice.
3.Nf3
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3.Nf3 Bg4 4.cxd5 Bxf3
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3.cxd5 Qxd5 4.e3 e5 5.Nc3 Bb4 6.Bd2 Bxc3
3...Bg4 4.cxd5 Bxf3 (see first diagram)
5.gxf3 Qxd5 6.e3 and now Black has two very different, but proven ways of playing 6...e5 7.Nc3 Bb4 and 6...e6 7.Nc3 Qh5.
5.dxc6 Bxc6 6.Nc3 and Black has now two well established options 6...Nf6 and 6...e6.
3...e6 is fine.
3.cxd5 Qxd5
4.e3 e5 5.Nc3 Bb4 6.Bd2 Bxc3 (see second diagram)
7.bxc3 and now black's main moves are 7...Nf6 and 7...Qd6.
7.Bxc3 has received considerable attention in recent years and 7...exd4 8.Ne2 Nf6 9.Nxd4 0-0 seems to be considered Black's most reliable choice, but the sharper 8...Bg4 is also sometimes played.
4. Nf3
Notes
^Alexander Morozevich & Vladimir Barskij, The Chigorin Defence According to Morozevich, 2007
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Matlab has a function called dmperm that computes the so-called Dulmage–Mendelsohn decomposition of a n x n matrix. From wikipedia, the Dulmage–Mendelsohn is a partition of the vertices of a bipartite graph into subsets, with the property that two adjacent vertices belong to the same subset if and only if they are paired with each other in a perfect matching of the graph. Looking both on scipy and numpy, I could not find this function, nor some similar version. Is it possible to implement it using basic linear algebra operations? Any idea if this is implemented in some Python package?
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