29 October 2014

Zugzwang

In the game of chess, a player is required when it is his or her turn. Sometimes a player would prefer to pass, but the rules do not permit it. This compulsion to move in a bad position is called zugzwang.

The player to move in this position will lose a pawn. Although this position is an example of zugzwang, it is not fatal. The loss of a pawn in this position does not mean the loss of the game.


In the next position, the player to move loses a pawn and the game.


In the third game of their match during the First American Chess Congress, 1857, Paul Morphy reached this position with Black against James Thompson.

Black to move

1...a1N+ wins easily. I tested this idea against Stockfish this morning and had no problems winning in a few minutes. However, even stronger would be 1...Bc3 and Morphy's 1...Ka3. Both moves place White in zugzwang.

26 October 2014

Pawn Structure Chess

McDonnell -- La Bourdonnais 1834

Readers may find a note of irony in my reasons for the gap of time between this post and the previous one concerning the first match between Alexander McDonnell (1798-1835) and Louis-Charles Mahé de La Bourdonnais (1795-1840). At the end of June, I started posting analysis of the games in this historic match between the top British player and the champion of France (see "Three Fighting Draws"). I kept up these posts with some regularity through game 22, but then abrubtly stopped in mid-September with three games remaining (see "La Bourdonnais's Infantry").

Teaching history cuts into my time for chess.

This neglect relates to McDonnell's career. At the time of the match McDonnell was secretary to the Committee of West Indian Merchants. This business group was involved in lucrative trans-Atlantic business ventures. I have been studying some of the broader contexts of these ventures.

I teach occasional college history classes for adult students. These classes are brief (six weeks) and quite intense in their focus. The past few weeks, I have been occupied with a new course--relatively new in the worlds of academia and my university and wholly new to me. It is called Atlantic World and covers history of four continents through three centuries. My academic training was focused on North America so I had much to learn preparing for this class.

A central facet of the Atlantic world was the trans-Atlantic slave trade and the production of sugar in the New World. Britain ended its participation in the trans-Atlantic slave trade in 1807 and abolished slavery in 1833. The time of McDonnell's work in West Indian business was a time of dramatic change.

Now that the end of my class draws near, I have more time for study of chess.

McDonnell prevailed in game 23, which was a battle centered on isolated pawns.

De Labourdonnais,Louis Charles Mahe -- McDonnell,Alexander [D00]
London m1 London (23), 1834

1.d4 d5 2.Bf4 c5 3.e3 Nc6 4.Nf3 Bg4 5.Be2 

In 2007, Vladimir Kramnik would play  5.c3.

5...Bxf3

Black creates a minor piece imbalance.

5...e6 was an alternative worth considering.

6.Bxf3 e6

White to move

7.c4

7.0–0 Nf6 8.c3 Be7 9.Nd2 0–0 10.Qb3 Qb6 11.Qxb6 axb6  and White won in 60 moves in Stoletov,G (2246) -- Kovalev,A (1955), Konakovo 2011.

7...Nf6 

From this pawn structure, an isolated queen pawn is common.

8.Nc3 cxd4 9.exd4 dxc4

White has an IQP; Black is a pawn ahead. Black's minor piece exchange deflected White's light-squared bishop from the f1–a6 diagonal.

10.0–0 Be7 11.Bxc6+

White eliminates the minor piece imbalance in order to win back the pawn.

11...bxc6 12.Qa4 0–0 13.Qxc4 

13.Qxc6 does not seem as good. 13...Rc8 14.Qa4 Qb6.

13...Rc8

It seems to me that White's IQP and Black's two isolated pawns should tip the balance slightly in White's favor.

14.a3 Bd6 15.Bg3

15.Bxd6 seems better 15...Qxd6 16.Qc5.
15.Bg5? is worse. 15...Bxh2+ 16.Kxh2 Ng4+ 17.Kg1 Qxg5.

15...Bxg3

White to move

16.fxg3?!

This move increases the mobility of the rook, but also places a burden upon the isolated d-pawn. This move also weakens the e3 square. Looking back from the conclusion of the game makes this move seem the first significant error.

I prefer 16.hxg3. But, even this move offers Black some opportunities. Perhaps White's troubles began on the previous move.

16...Nd5 17.Rae1

Guarding e3

17...Qg5

Increasing pressure on e3.

18.Ne4

Driving the queen back.

18...Qe7 19.b4?!

Another plan might have been 19.Nc5 blockading the isolated c-pawn. White could then place his queenside pawns on b3 and a4. However, Black might then build up pressure on d4. 19...Nb6 20.Qa6 Rfd8 21.Rd1 Rd5 22.Rd2 Rcd8 23.Rfd1 e5! 24.Qe2.

19...a5

Any advantage that White might have realized with fewer isolated pawns will be gone soon.

20.Nc5 axb4 21.axb4 Rb8

White's queen may be compelled to defend White's two isolated pawns, although only one is attacked at present.

White to move

22.Na6?

This move seems to fail tactically.

22.Rb1 Rb5 23.Nd3 Qb7.

22...Rb6 23.b5 Qa3

Black again puts pressure on e3

24.Qc5

24.Ra1 Qe3+ 25.Kh1 cxb5 26.Qc5 b4 and White will need to give up a piece to stop Black's b-pawn.

24...Qxc5 25.Nxc5 Rxb5 

White to move

26.Nd7

26.Rc1 Rd8 27.Rfd1 Ne3 28.Rd3 Nf5 29.Nb3 Rbd5 30.Rxc6 Kf8 31.Rc4 e5 and Black should win.

26...Rc8 27.Ne5 Rb7 28.Rc1 Rbc7 29.Rc5

29.Nd3 c5 30.dxc5.

29...f6 30.Nc4 Kf8

White to move

31.Ra1

La Bourdonnais aims to collect Black's c-pawn. This plan is doomed.

31.Nd6 Rb8 32.Ne4.

31...Ke7 32.Ra6 Nb4 33.Ra4 Rb8! 34.Na5

Black to move

This position is useful for instructing elementary chess students.

34...Nd3

White is losing material due to the checkmate threat. The tactic combines fork and discovery. A line is opened for the rook while the knight forks rook and the king's escape square.

35.Kf1

35.Rc3 Rb1+ and checkmate next move.

35...Nxc5 36.dxc5 Rb5 0–1

McDonnell's play against pawn weaknesses gave hi the win.

24 October 2014

Painful Memory

In 2005, I was playing an underrated elementary age youth late at night at the Spokane Chess Club. It was part of one of our summer quad events. A critical position was reached when he played 21.bxc3 and offered a draw. I was down an exchange plus a pawn.

Black to move

The next morning I awoke from a deep sleep at about 3:00 am and immediatly set up the game in Fritz. I required less than five minutes to demonstrate what I should have seen several hours earlier.

What did I learn in my sleep?

23 October 2014

Lesson of the Week

Essentials of Rook Endings

My primary chess club had been divided into groups meeting on different days by age in years past. This year the division was changed to one based on skill. Consequently, my beginning* group on Tuesdays receives different instruction than the advanced group on Thursdays. Members of my in-school chess class and those who have contracted with me for individual lessons will get one or another of these lessons when appropriate.

The beginning group this week is working on recognizing checkmate. Interested parents may contact me to recieve a copy of the Checkmate in One exercise they will be working through over the next several weeks. I created a set of 48 positions from actual play. In every position, there is a possible checkmate on the move. My beginning group worked through the first six this week.

The advanced group is working through developing plans and correctly evaluating a series of positions that arose, or could have arisen, in one of my online games. My game ended in a textbook draw that my opponent insisted upon playing out. Along the way, we both missed clear winning chances during the course of a rook ending.

The first position occured near the end of the game. White recognizes that the position has reached the textbook Philidor Position that he had been aiming at for the past few moves.

White to move

White draws by occupying the third rank with his rook. The game continued 67.Ra3+ Kd4 68.Ke1 e3. Now that Black has advanced the pawn, White resorts to checks from the rear. Black cannot escape these checks and also maintain the pawn.

69.Ra8 Ke4 70.Re8+ and the game went on another twelve moves with White continuously checking the Black king.

The second instructive position comes from the moment when Black missed a win.

Black to move

After 54.Ra4+, Black played 54...Kd5. 54...Kd3! on the other hand would have facilitated the advance of the e-pawn and victory.

In the third instructive position for this week, White missed a chance for a clear advantage.

White to move

Black has just played 42...f5? White played 43.c4 and later let the game slip further away. However, he might have played 43.h4!

After 43.h4, Black's best chance requires the sacrifice of a pawn. 43...f4 44.Rxf4 Rb5+ 45.Kc4 and White has a clear advantage, albeit not necessarily a winning advantage.

There are many interesting positions that arise after 43.h4! Kd7?

One that is part of my lesson plan arises after the continuation 44.Rf4 Kc6 45.a4 Kd6 46.c4 Kc6 47.a5! b5

White to move

White's best move appears to be 48.d5! A possible line is 48...exd5 49.cxb5+ axb5 50.a6!

Either the a-pawn will promote, or all of both sides' pawns on the a- through e-files will be liquidated and the White king will march over to nab the trapped rook.



*Beginning and advanced are fuzzy terms in the chess world. From the perspective of a super-Grandmaster, everyone under 2000 Elo is a beginner. That definition includes me. For purposes of my after school chess club for elementary age children, advanced players are those who have qualified for the Washington State Elementary Chess Championship. Qualification each year requires scoring 3/5 or better in a qualifying tournament.

19 October 2014

Opportunity

When a tactical opportunity presents itself, seize it. Perhaps Black thought that he won a pawn with 33...Nxf2. This position arose in Miroshnichenko -- Rychagov, Sochi 2005. I found the game while exploring options for Black in the Catalan after 6.Qc2 dxc4 7.Nbd2, which scores very well for White.

White to move

18 October 2014

Knight Forks

When I get a new copy of Chess Informant, I play through all of the games published therein that are classified C00-C19. These are the Encyclopedia of Chess Openings (ECO) classifications for the French Defense.* New on my computer are the download versions of CI 119, CI 120, and CI 121. These electronic publications are in ChessBase format.

This morning I glanced through an excellent instructive article on pawn endings in Informant 120, "Precision" by Eduardas Rozentalis. Then I started working through the French Defense games. Naturally, the tactics in these games are instructive.

The position below appears in the notes to CI 120/100 Solak -- Bartel, Yerevan 2014.

White to move

The correct move in this position is the final one in Solak's annotations. He leaves the reader to work out why it is a winning move.

I may use this position with some of my students next week. After White's move and an obvious looking subpar response by Black, a position is reached that may be useful with some of my beginning students.


*ECO Code is a trademark of Chess Informant.

16 October 2014

Superficial Analysis

Correcting Errors

There is no substitute for calculation. Intuition can be helpful in chess and sometimes even helps humans see some things that computers miss. However, a quick glance and reliance upon intution can mislead.

In yesterday's post, "The Final Transition," I offered the view that an exchange of bishops that had not taken place was necessary to avoid because it would have given White a clear win. I was wrong. That position is still a draw.

Black to move

In the game, Black played 47...Bb4+.

I stated in "The Final Transition" that 47...Bxd4+ was a losing move for Black. I saw at a glance 48.Kxd4 axb3 49.axb3 and judged this position as "hopelessly lost" for Black.

Black to move

White does indeed win after 49...Kb4 50.Kxd5 Kxb3 51.Ke5 Kc4 52.Kf6 Kd5 53.Kg7 Ke6 54.Kxh7

Black to move

However, Black has another option: 49...Kc6!

After 50.b4 Kd6 51.b5 Black has 51...g5!

White to move

When White wins the h-pawn, Black will be able to trap the White king on the h-file. In the diagram presented above for the line that began 49...Kb4, White had a reserve tempo with the pawn. In this last position, that is no longer possible.

I had stated in "The Final Transition" that intermediete students would find the position in the first diagram above instructive. Although I have corrected my own understanding of the consequences of the bishop exchange, I still believe the position will be useful. It will the lesson with my chess students today.

15 October 2014

The Final Transition

While beginning to explore the exciting material in Chess Informant 121, I came across an ending of value to intermediate students. In this game from the recent Olympiad, Markos -- Leitao, Tromso 2014 (CI 121/82), White sacrificed his queen for the purpose of placing a dangerous pawn on the seventh rank.

Black to move

Black played 34...Qd8 and twenty moves later the game ended as a draw. Chess teachers can find several positions in the last twenty moves worth putting in front of beginning and intermediate students with a question: should Black exchange bishops?

For example, After 47.Bd4.

Black to move

The average reader of Chess Informant does not need a prompt to recognize that 47...Bxd4 offers Black a hopelessly lost pawn ending.* However, this position should prove instructive when I put it in front of youth players who are struggling to rise to the level of solid C and D Class players.

Back to the first diagram, Rafael Leitao, who annotated the game for Informant noted the pitfall that he avoided. 34...Kf7? 35.Bxe7 Kxe7 36.Rc8 Qa5 37.d8Q+ Qxd8 38.Rxd8 Kxd8 39.Kf1.

Black to move


White would have had an elementary win in this pawn ending. Even so, my students may need to play this position out a few moves in order to understand how White wins.

After White's queen sacrifice, Black had to examine the bishop and pawn ending as well as a couple of possible pawn endings. Kf7 would be played, but the move order was critical. Black chose the correct transition to an ending with the bishops on the board.


* Edit 16 October: My superficial analysis led to gross error. The position that would have resulted had Black opted to exchange bishops on move 47 is not "hopelessly lost" for Black. See "Superficial Analysis".