Tune Your Chess Tactics Antenna

by Emmanuel Neiman

  Tactically, the double attack is simpler: it simply means to simultaneously attack two unprotected (or insufficiently protected) points. The study of the motif is very important, and it should give a serious clue to the searcher. Additionally, we can spot possible weaknesses, which we will turn into undefended points by sacrifices.

  Most of the time, the second theme that is linked with the double attack is the decoy, which means luring a piece to a specific square on which, in our chapter, we will be able to deliver a double attack.

  Let’s begin with a light trap:

  Neiman,Emmanuel

  Velikov,Petar

  Evry 2002 (7)

  1.d4 d5 2.Bg5 c6 3.e3 h6 4.Bh4 Qb6 5.b3 e5

  The last move ‘sacrifices’ a central pawn. Knowing the cautious style of my opponent, I suspected some trick and did not dare to take the pawn.

  After

  6.dxe5

  (6.Nf3 was played in the game) the double attack is possible thanks to the opening of the fourth rank. The two weak points are:

  - one bishop on an unprotected square;

  - the possibility to give check to the white king.

  6…Qb4+

  Followed by 7…Qxh4.

  Double threat

  Biriukov,Nikolay

  Yilmaz,Mustafa Enes

  Kharkov 2011 (5)

  The queen is the classical executioner of a double attack.

  1.c4 e5 2.Nc3 Nc6 3.g3 g6 4.Bg2 Bg7 5.e4d6 6.d3 Nd4

  7.Nce2 Ne6 8.Nf3 Ne7 9.d4 0-0 10.0-0 f5 11.exf5 gxf5 12.d5 Nc5 13.Ne1 f4 14.gxf4 Ng6 15.fxe5 Nxe5 16.Ng3 Nxc4 17.Rb1 Bd7 18.Nh5 Bh8 19.b4 Bf5 20.bxc5 Bxb1 21.Nf4 Bf5 22.Ne6 Qh4 23.Nf3 Qg4 24.h3 Qh5 25.Nf4 Qe8 26.Nh4 Qf7 27.Ne6 dxc5 28.Bh6 Rfd8 29.Nxd8 Rxd8

  Once you have spotted the two weaknesses, the double attack is not hard to find. Of course, the rook on d8 and the knight on c4 are both unprotected and located on open lines. This is a case for her majesty.

  30.Qc1!Rd6 31.Qxc4

  1-0

  31…Rxh6 32.Nxf5 Qxf5 33.d6++−and 34.dxc7 is winning.

  Le Roux,Jean Pierre

  Hamdouchi,Hicham

  Caen ch-FRA 2011 (1)

  1.Nf3 Nf6 2.c4 g6 3.d4 Bg7 4.g3 0-0 5.Bg2 c6 6.Nc3 d5 7.cxd5 cxd5 8.Ne5 e6 9.0-0 Nfd7 10.Nf3 Nc6 11.e4 dxe4 12.Nxe4 h6 13.Be3 Nb6 14.Rc1 Nd5 15.Nc3 Nce7 16.Nxd5 Nxd5 17.Bd2 Qb6 18.Qa4 Rd8 19.Ne5 Qxb2 20.Bxd5 exd5

  21.Rc2 Qb6 22.Rfc1 Bh3 23.Rc7 Rf8 24.Bf4 g5 25.Be3 Rad8 26.Nd7

  White has created a kind of double attack here, with the knight fork on d7. The main point in this position is the weakness of the light squares around the white king. Black was able to elegantly apply our theme:

  26…Rxd7

  First the rook is lured to d7.

  27.Rxd7 Qe6!

  Attacking the rook, and also threatening mate after 28…Qe4. There’s no escape. If 28.Rdc7, 28…Qe4 wins.

  Bartel,Mateusz

  Nikolaidis,Joannis

  Eretria 2011 (1.4)

  1.d4 Nf6 2.c4 d6 3.Nc3 Nbd7 4.e4 e5 5.Nge2 c6 6.f3 a6 7.Be3 Be7 8.d5 cxd5 9.cxd5 Nh5 10.Qd2 g6 11.0-0-0 b5 12.Ng3 Ndf6 13.Kb1 Bd7 14.Nce2 a5 15.Nxh5 Nxh5 16.g4 Ng7 17.h4 h5 18.g5 0-0 19.f4 Bg4 20.fxe5 Bf3 21.Rh3 Bxe4+ 22.Ka1 Bf5 23.Rh1 Bg4 24.Bh3 Bxh3 25.Rxh3 Qd7 26.exd6 Bxd6 27.Rhh1 Nf5

  28.Bf4 Rfe8 29.Bxd6 Qxd6 30.Nc3 b4 31.Nb5 Qd7 32.Nd4 Ne3 33.Nc6 Nxd1 34.Rxd1 Re4 35.Qd3 Rae8 36.Nxa5 R8e5 37.d6 Re3 38.Qd2

  Black had a very simple win available here. Can you spot the two weaknesses (two undefended points) that allow Black to win, thanks to a double attack? 38…R3e4 was played in the game, which was ultimately won by White.

  38…Rxa5

  was easily winning as after the normal

  39.Qxe3

  a double attack is available: 39…Qa4!, threatening mate in one while attacking the rook on d1. The game would have immediately ended in Black’s favour.

  Double Attack

  Do you see how White can realize a double attack here?

  27.e6!

  This pawn push reveals the possibility to attack Black’s two unprotected rooks simultaneously.

  27…fxe6

  Black has to take, because f7 was attacked.

  28.Qe5

  winning a rook.

  Thanks to the poor king’s position, 28.Rfe1, for example, would also win, but we prefer the double attack!

  Sometimes, the attacker notices one possible attack on an unprotected point. In this case you should not attack this weakness right away, but wait until you can create a second one, which will allow you to create a double attack.

  Once you notice the chance to make a double attack, the typical device is to lure the second unprotected piece to the losing square with a decoy.

  Two classic examples:

  Spassky,Boris

  Averkin,Orest

  Moscow ch-URS 1973 (2)

  1.e4 c5 2.Nf3 Nc6 3.d4 cxd4 4.Nxd4 e6 5.Nb5 d6 6.c4 Nf6 7.N1c3 a6 8.Na3 Be7 9.Be2 0-0 10.0-0 Bd7 11.Be3 Rb8 12.Rc1 Qa5 13.f4 Rfd8 14.Qd2 Be8 15.Rfd1 Nb4 16.Qe1 b5 17.Kh1 Rdc8 18.cxb5 axb5 19.e5 dxe5 20.fxe5 Nd7

  21.Naxb5 Nxe5 22.Bf4 Ned3 23.Bxd3 Nxd3 24.Rxd3 Bxb5 25.Rg3 Rb6

  If you look at possible weak points in Black’s position, you will notice the g7-square, attacked once by the rook on g3, and defended only once by the king. The obvious attack with 26.Qe5, threatening mate in one, would easily be repelled, of course. So White has to create a second weakness, which will allow him to attack two objects at the same time.

  Here an examination of the motifs can help us. There’s another interesting piece arrangement that has to be spotted: the alignment on the d8-a5 diagonal of Black’s queen and rook.

  This should be a strong enough hint for you to find the clinical solution:

  26.Bc7!Rxc7 27.Qe5 g6

  The best defensive try was 27…Kf8! 28.Qxc7 Bd6 29.Qd8+ Be8 and Black has a defendable position.

  28.Qxc7 Bh4 29.Rf3 Be8 30.Rxf7 Bxf7 31.Rf1 Be8 32.Qc8 Kg7 33.Qxe8 Bf6 34.Ne4 e5 35.Nxf6

  1-0

  Another decoy enables White to win material by creating a second weakness in the following game:

  Kasparov,Garry

  Ligterink,Gert

  Malta ol 1980 (6)

  1.d4 Nf6 2.c4 e6 3.Nf3 b6 4.g3 Bb7 5.Bg2 Be7 6.Nc3 Ne4 7.Bd2 Bf6 8.0-0 0-0 9.Rc1 c5 10.d5 exd5 11.cxd5 Nxd2 12.Nxd2 d6 13.Nde4 Re8 14.Qd2 a6 15.b4 Be7 16.bxc5 bxc5 17.Qf4 Qc7 18.Na4 Qa5 19.Rb1 Bxd5 20.Nb6 Bxe4 21.Bxe4 Ra7

  Again we can notice a weak point on the kingside: h7 is attacked once and defended once. A direct and brutal attack would be a loss of time, but taking into account this possibility, we can try to create a second weakness. Once again a study of the signals helps us: the forking distance between a rook on c8 and square h7 for the white queen. Hence, logically, the first move is the clever

  22.Nc8!

  Attacking the rook on a7 and the knight on b8.

  22…Rxc8

  In the game there followed 22…Nc6 23.Nxa7 Nxa7 24.Bd5 and Black resigned.

  23.Qf5

  A double attack that wins easily.

  Exercises

  Exercise 1 Signal 2

  *

  Novikov,Igor

  Rhodin,Christian

  Bern 1993 (2)

  1.d4 Nf6 2.c4 e6 3.Nf3 b6 4.g3 Bb7 5.Bg2 Be7 6.0-0 0-0 7.b3 c5 8.Nc3 Ne4 9.Bb2 Bf6 10.Qd3 d5 11.cxd5 Nxc3 12.Bxc3 cxd4 13.Bb4 Ba6 14.Qd2 Re8 15.Nxd4 Bxd4 16.Qxd4 Nc6 17.Qg4 Nxb4 18.dxe6 Rxe6 19.Rfd1 Qf8 20.Bxa8 Bxe2 21.Bf3 Bxd1 22.Rxd1 Qe7 23.a3 Nc6

  (Solution on page 147)

  Exercise 2 Signal 2

  *

  Bacrot,Etienne

  Vachier-Lagrave,Maxime

  Bastia rapid 2012 (3)

  1.Nf3 c5 2.c4 Nc6 3.d4 cxd4 4.Nxd4 Nf6 5.g3 e5 6.Nb5 Bb4+ 7.Bd2 a6 8.Bxb4 axb5 9.Bd6 Ne4 10.Bg2 Qa5+ 11.b4 Nxb4 12.Bxe4 Nc2+ 13.Kf1 Nxa1 14.Bxe5 Qxa2 15.Bxg7 Rg8 16.Bf6 Ra6 17.Bxa1 Qxa1 18.cxb5 Rh6

  (Solution on page 147)

  Exercise 3 Signal 2

  *

  San Segundo Carrillo,Pablo

  Rodriguez Vargas,Orestes

  Salamanca 1991 (2)

  1.e4 c5 2.Nf3 d6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 N
c6 6.Bg5 Bd7 7.Nb3 e6 8.Qd2 a6 9.0-0-0 b5 10.a3 b4 11.axb4 Nxb4 12.f4 Be7 13.e5dxe5 14.fxe5 Nfd5 15.Bxe7 Qxe7 16.Nxd5 exd5 17.h4 0-0 18.Qg5 Qe8 19.h5 h6 20.Qf4 Rb8 21.Bd3 Be6 22.g4 f6 23.exf6 Rxf6 24.Qd4 Qf8 25.g5 hxg5 26.Rde1 Rf4 27.Qe3 Nxd3+ 28.Qxd3 Re4 29.Nc5 Qf4+ 30.Kb1

  (Solution on page 147)

  Exercise 4 Signal 2

  **

  Lasker,Emanuel

  Euwe,Max

  Nottingham 1936 (13)

  1.d4 d5 2.c4 c6 3.Nf3 Nf6 4.e3 Bf5 5.Bd3 e6 6.cxd5 Bxd3 7.Qxd3 exd5 8.Nc3 Bd6 9.0-0 0-0 10.Re1 Nbd7 11.e4 dxe4 12.Nxe4 Nxe4 13.Qxe4 Re8 14.Qxe8+ Qxe8 15.Rxe8+ Rxe8 16.Kf1 Nb6 17.Bd2 f6 18.Re1 Rxe1+ 19.Nxe1 Kf7 20.Ke2 Ke6 21.h3 Nc4 22.Bc1 Bc7 23.Kd3 Ba5

  (Solution on page 147)

  Exercise 5 Signal 2

  **

  Ivanov,Sergey

  Westerburg Jonathan

  Stockholm 2011/12 (3)

  1.d4 Nf6 2.Nf3 e6 3.c4 b6 4.g3 Ba6 5.Qc2 Bb7 6.Bg2 c5 7.d5 exd5 8.cxd5 Nxd5 9.0-0 Be7 10.Rd1 Nf6 11.Nc3 d5 12.e4 0-0 13.e5 Ne8

  (Solution on page 148)

  Exercise 6 Signal 2

  ***

  Tikkanen,Hans

  Goudriaan,Etienne

  Wijkaan Zee C 2012 (4)

  1.c4 Nf6 2.g3 e6 3.Bg2 d5 4.d4 Be7 5.Nf3 0-0 6.0-0 dxc4 7.Qc2 b5 8.a4 b4 9.Bg5 Nbd7 10.Ne5 Nxe5 11.Bxf6 gxf6 12.dxe5 Rb8 13.Rd1 Qe8 14.Qxc4 Bb7

  14…Bd7 15.b3.

  (Solution on page 148)

  Chapter 10

  Alignment

  Alignment is a very common motif, which will enable you to realize many tactical themes: the pin, the skewer, the discovered attack and line clearance being the main ones. Some examples:

  Pin

  Meier,Georg

  Kramnik,Vladimir

  Dortmund 2011 (2)

  1.d4 Nf6 2.c4 e6 3.Nf3 b6 4.g3 Ba6 5.b3 Bb4+ 6.Bd2 Be7 7.Bg2 0-0 8.Nc3 d5 9.cxd5 exd5 10.0-0 Re8 11.Rc1 Bb7 12.Ne5 Na6 13.Bf4 h6 14.Nb5 Bf8 15.Bh3 c5 16.a3 Ne4 17.Rc2 g6 18.Qc1 g5 19.Be3 Bg7 20.Nf3 Qe7 21.Rd1 Rad8 22.Nxa7 Nd6 23.a4 Nb4 24.dxc5 bxc5 25.Rxc5 Na2 26.Qc2 Nb4 27.Qc1 Nc4 28.bxc4 d4 29.Bxg5 Qxc5 30.Bxd8 d3 31.Ne1 Rxe2 32.Qf4

  In this hot game, Black now wins thanks to a possible pin. Black provokes an alignment of White’s king and queen, and uses it in order to pin them.

  32…Rxf2!

  0-1

  On 33.Qxf2 (33.Qb8 Rf4#) 33…Bd4 is easily winning.

  Pin

  Lombardy,William

  Polugaevsky,Lev

  Reykjavik 1978

  1.c4 Nf6 2.Nc3 e6 3.Nf3 Bb4 4.Qc2 c5 5.a3 Ba5 6.g3 Nc6 7.Bg2 0-0 8.0-0 Qe7 9.d3 h6 10.e3 d6 11.b3 Bd7 12.Bb2 Rab8 13.d4 cxd4 14.exd4 Rfc8 15.b4 Bd8 16.Rfe1 Qf8 17.Qd3 Ne7 18.Nd2 b6 19.Nb3 a5 20.d5 e5 21.Nb5 Ne8 22.Rac1 axb4 23.axb4 Rb7 24.Nd2 Ng6 25.h4 f5 26.Ra1 e4 27.Qb3 Bf6 28.Na7 Bxb2 29.Qxb2 Rcc7

  30.Nc6!

  The beginning of a deep combination, which is based on various alignments and pins.

  30…Bxc6 31.dxc6 Rxc6

  32.Nxe4! fxe4 33.Bxe4 Ne7 34.Ra8!

  A terrible pin. White is threatening to take on c6 and then on e8.

  34…Rcc7 35.Bg6!?

  It was also possible to strengthen the pin along the eighth rank with 35.Qa2, controlling a7: 35…Kh8 36.Bxb7 Rxb7 37.Rd8 Kh7 38.Qa8 and wins.

  35…Nxg6 36.Rexe8

  1-0

  Pins

  Arjun,Bharat

  Leer-Salvesen,Bjarte

  Stockholm 2011/12 (4)

  1.Nf3 d5 2.c4 e6 3.g3 Nf6 4.Bg2 Be7 5.0-0 0-0 6.b3 c5 7.e3 Nc6 8.Nc3 d4 9.exd4 cxd4 10.Ne2 e5 11.d3 h6 12.a3 a5 13.Rb1 Bf5 14.Nh4 Bh7 15.f4 exf4 16.gxf4 Ng4 17.Nf3 Ne3 18.Bxe3 dxe3 19.d4 Bxb1 20.Qxb1 Bxa3 21.d5 Nb8 22.Nfd4 Re8 23.Rf3 Ra6 24.Nf5 Bf8 25.Rg3 Rg6 26.Rxg6 fxg6 27.Nfd4 Qf6 28.Ne6 Nd7 29.Qc1 Kh8 30.Bh3 Qh4 31.Qxe3

  The white queen and king are aligned. So are White’s knight and queen. Thanks to those pins, Black wins by force:

  31…BC5!

  This pin is fatal; it wins the exchange and the game.

  32.N2d4 Qf6

  32…Nf8 was even stronger: 33.Qg3 (on 33.Kg2, Nxe6 and Qf6 wins.) Qxg3+ 34.hxg3 Nxe6 35.Bxe6 Bxd4+.

  33.Kg2 Bxd4 34.Qxd4 Rxe6! 35.Qxf6 Rxf6 36.Bxd7−+ Kg8

  Black wins easily in the ending.

  37.Be6+ Kf8 38.Kf3 Ke7 39.c5 Rf8 40.Ke4 b6 41.Ke5 bxc5 42.d6+ Kd8 43.h4 Rf6 44.Bh3 Rf7 45.Be6 Rb7 46.Bc4 Rb4 47.Kd5 a4 48.bxa4 Rxa4 49.Kxc5 Ra3 50.Bf7 Ra5+ 51.Kc6 Rh5 52.Bxg6 Rxh4 53.f5 Rh1 54.Kd5 Kd7 55.f6 Rd1+ 56.Ke5 Re1+ 57.Be4 gxf 6+ 58.Kf5 Rxe4

  0-1

  Discovered attack

  Yu Ruiyuan

  Oleksienko,Mikhail

  Chennai Open 2012 (7)

  1.e4 c5 2.Nf3 d6 3.Bb5+ Nd7 4.d4 a6 5.Bxd7+ Bxd7 6.0-0 cxd4 7.Qxd4 Bg4 8.Qd3 Nf6 9.Bg5 e6 10.c4 Be7 11.Nc3 0-0 12.Nd4 h6 13.Bh4 g5 14.Bg3 Bh5 15.Nde2 Qb6 16.Kh1 Rfd8 17.f4 Qxb2 18.Rab1 Qa3 19.Rb3 Qc5 20.Rxb7 Rd7 21.Bf2 Qa5 22.Rb2 Rc8 23.Bd4 Bxe2 24.Nxe2 gxf4 25.Nxf4 e5 26.Bb6 Qa4 27.Nd5 Nxd5 28.cxd5 Bg5 29.Qf3 Rb8 30.Qg4 Kh8 31.h4 Bf4

  Here we can notice that the undefended rook on b8 is aligned with the white rook on b2.

  We can exploit this with a preparatory sacrifice:

  32.Rxf4!

  1-0

  If Black accepts with 32…exf4 (32…Rg8 33.Qh5 exf4 34.Qxh6#) now comes the discovered attack: 33.Bd4+ Qxd4 34.Rxb8+ Kh7 35.Qg8#.

  Decoy/Discovered Attack

  Schindler, Christian

  Wagner,Dennis

  Osterburg ch-GER 2012 (1)

  1.d4 d5 2.c4 dxc4 3.e3 e5 4.Bxc4 exd4 5.exd4 Bd6 6.Nf3 Nf6 7.Qe2+ Be7 8.0-0 0-0 9.Re1 Bb4 10.Nc3 Nc6 11.a3 Ba5 12.b4 Bb6 13.d5 Re8 14.Qd1 Rxe1+ 15.Qxe1 Nd4 16.Nxd4 Bxd4 17.Be3 Bxc3 18.Qxc3 Nxd5 19.Bxd5 Qxd5 20.Qxc7 b6 21.Rc1 Bb7 22.Qg3 Rd8 23.Re1 h5 24.h4 Rd6 25.Qg5 Qc6 26.f3 Qc3 27.Re2 Bxf3 28.Rf2 Bc6 29.Qe7 Rd7 30.Qg5 Rd3 31.Bf4 f6 32.Qxh5 Qd4 33.Qe2 Be4 34.Kh2 Rxa3 35.Bg3 Re3 36.Qg4 Re1 37.h5

  Here the alignment is between the white and the black queen, only separated by the black bishop; hence the idea of a discovered attack prepared with

  37…Rh1+!

  A decoy that forces White ‘s king to go to a light square.

  38.Kxh1 Bxg2+

  0-1

  The white queen is lost.

  Line Clearance/Discovered Attack

  Izeta Txabarri,Felix

  Peric,Slavisa

  Suances Open 1997

  1.d4 d5 2.c4 dxc4 3.Nf3 c5 4.e3 e6 5.Bxc4 Nf6 6.Qe2 cxd4 7.exd4 Be7 8.0-0 a6 9.Nc3 0-0 10.Bg5 Nc6 11.Rad1 Re8 12.Ne5 Nb4 13.f4 Nbd5 14.f5 Rf8 15.Nxf7 Rxf7 16.fxe6 Rf8 17.Nxd5 Nxd5 18.Bxe7 Nxe7 19.Rxf8+ Qxf8 20.d5 b5 21.Bb3 Bb7 22.d6 Rd8 23.dxe7 Rxd1+ 24.Qxd1 Qxe7

  A very simple and classical example of a fatal alignment. The white bishop and the black king are aligned, only separated by the pawn on e6, which is kept at bay by the black queen. In such a situation, the greatest sacrifice can be made in order to open the diagonal, and that is what Izeta did – he gave the queen:

  25.Qd8+!

  1-0

  Mate cannot be avoided, for example: 25…Qxd8 (25…Qf8 26.e7+ Kh8 27.exf8Q#) 26.e7+ Qd5 (26…Bd5 27.Bxd5+Qxd5 28.e8Q#) 27.e8Q#.

  Skewer/Discovered Attack

  Karpov,Anatoly

  Topalov,Veselin

  Dos Hermanas 1994 (9)

  1.d4 Nf6 2.Nf3 c5 3.d5 e6 4.Nc3 Nxd5 5.Nxd5 exd5 6.Qxd5 Be7 7.e4 0-0 8.Be2 d6 9.0-0 Nc6 10.c3 Be6 11.Qh5 h6 12.Rd1 Re8 13.Bf4 Bf8 14.Nd2 g6 15.Qf3 d5 16.Qg3 Qe7 17.exd5 Bxd5 18.Bf1 Qf6 19.Nb3 Rad8 20.Rd2 Be6 21.Bc7 Rxd2 22.Nxd2 Bf5 23.Nc4 Re4 24.Ne3 Bc8 25.Rd1 Re8 26.h3 Qg5 27.Qf3 Kg7 28.Bf4 Qe7 29.Nd5 Qe4

  30.Nf6!

  A fork intended to decoy the king onto the f-file.

  30…Kxf6

  30…Qxf3 31.Nxe8+ Kg8 32.gxf3 nets White a rook.

  31.Be5+!

  This is the point. The discovered check involves the sacrifice of a second minor piece, but very soon White will be an exchange up.

  31…Kxe5

  Black is two pieces up at the moment, but he will soon be forced to give up a rook and a bishop due to several alignments.

  32.Qxe4+

  A clear-cut solution, entering a winning endgame. The typical computer move 32.Qxf7!? also wins, because next, 33.f4+ will win the queen or mate within a few moves.

 
32…Kxe4 33.Re1+ Kf5 34.Rxe8

  With a double attack on both bishops. The game is over because such a rook is too strong compared to a minor piece in endgames.

  34…Be6 35.Rxf8 Bxa2 36.Rc8

  With 37.Rc7 to come, for example 36…Bd5 37.Rc7 b6 38.c4, winning a piece. Black resigned.

  Discovered Attack

  Cetkovic,Momcilo

  Molerovic,Milivoje

  Yugoslavia 1951

  This position contains many favourable motifs for White:

  - Black’s queen is cornered, and situated on the same rank as White’s;

  - the black king is not well placed either; it stands in the middle of the board, with open lines leading to it. The beautiful discovered attack

  1.Bh7!!

  threatening mate in one, and to take the queen, wins on the spot.

  Another win was 1.Ra1 Qb2 2.Rfb1 Qc3 and now a very technical move: 3.Bd3! and the queen will be caught on the next move with Bd2 (the immediate 3.Bd2 allows 3…d3! with some chances of survival – not 3…Qxc2 because of the discovered attack 4.Bxh6+).

  Exercises

  Exercise 1 Signal 3

  *

  Dolzhikova,Olga

  Spirin,Oleg

  Oslo 2011 (9)