28 May 2017

Bishop and Knight Checkmate

Forcing checkmate with a bishop and knight requires piece coordination and foresight. It is the most difficult of the elementary checkmates. I remember being on the weaker side in a game on the Internet Chess Club in the late 1990s. I told my opponent, "I think this is a draw." He was convinced that it was a win, but he tried to checkmate me in the wrong corner. The game was drawn by the fifty-move rule. After the game, I looked it up. He was right and I was wrong.

Shortly after that game, I learned the checkmate through study of several key positions in Bruce Pandolfini, Pandolfini's Endgame Course (1988). Occasionally, in blitz games or against Chessmaster, I would underpromote a pawn so that I could execute this checkmate. Those instances were usually simple, as only a few moves were needed for checkmate.

I required students to demonstrate it for the Rook Award when I first created my youth chess awards. When I was teaching it regularly, I could perform it reasonably fast, but not easily. Ten years ago, however, I was persuaded by Jeremy Silman to drop it from my awards. It is excluded from Silman's Complete Endgame Course (2007) because it almost never occurs in actual play. In its place in my awards are the Philidor and Lucena rook endgame positions. There should be no question that rook endgames occur frequently and are of immense practical value. The Philidor and Lucena positions also are easier to teach.

Last year in a blitz game at the Spokane Chess Club, I underpromoted and then struggled to execute the checkmate. It had been several years since I practiced this checkmate regularly and my skills had atrophied. Success came well after the fifty-move mark. Last week, I tried the checkmate using Chess.com's "Drills" feature. Again, I struggled. To repair my deficiency, I went to YouTube and watched a video by NM Elliott Neff and another by IM Daniel Rensch. Both of these videos are excellent. After watching these videos, I succeeded with the drill quickly and easily. But, the next morning, I struggled again. Something about the knight's W pattern eluded me. Had I been more attentive during the last two minutes of Neff's video, I might have understood it better.

White to move
The W

Through the past few days, I have watched eight or ten videos, reread the relevant portions of Pandolfini's Endgame Course, and read the bishop and knight section of Karsten Muller and Frank Lamprecht, Fundamental Chess Endings (2001). I also have played out dozens of positions against Stockfish on my iPad. I have been in the diagram position above in game after game. I have played this position so often that my hand is learning the moves.

Transition to the Lock

For many years, I have had a vague memory of Pandolfini's Endgame 22, "Transition to the Lock".

White to move

1.Bg5 Ke8 2.Ng6

2.Ke6 is an easier system to remember.

2...Kf7 3.Ne5+ Ke8 4.Kc7

Black to move

When I was failing, I was always aiming at this position, but the bishop and knight swapped places in my memory. As a consequence, Black was able to shuffle the king between e7 and e8 and White failed to make progress. With these two minor pieces in their correct positions, the finish is easy.

4...Kf8 5.Kd7 Kg8 6.Ke8?!

6.Bh6 was the correct move.

6...Kg7 7.Ke7 Kg8

White to move

8.Bh6 Kh7 9.Bf8 Kh8 10.Kf7 Kh7

White to move

11.Nd7 Kh8 12.Bg7+ Kh7 13.Nf6#.

The Drill

Chess.com's drill employs the position that tablebases have identified as the one requiring the most moves to checkmate. This position is among those listed in the appendix in Fundamental Chess Endings. The engine Chess.com uses is less accurate than Stockfish on my iPad, or so it seems. With optimal play on both sides, this position leads to checkmate in 33 moves. Neither I nor the computer played the best moves.

There are three steps in the process:

1) centralize and drive the king to the edge,
2) drive the king from wrong corner to right corner,
3) checkmate.

White to move

Among the videos that I watched this week, some were better than others. One that is okay, but not to be recommended, is Kevin's from thechesswebsite.com. Through the first phase, he keeps repeating, "it doesn't matter," or similar phrases. I disagree. While slight inaccuracies in the first phase will not be the determining factor in success or failure, they can add up. When you have 50 moves to execute a checkmate that requires 33, an inaccuracy that requires four or five moves to correct can be repeated twice. The third time could be fatal. The inaccuracies through the first eleven moves here, however, add only one or two moves each to the final solution. Had the computer been more stubborn, however, checkmate might have occurred on move 40.

Stripes,J -- Computer
Chess.com, 26.05.2017

1.Ka7 Kd8 2.Bg6 Kc7 3.Nf3 Kc6 4.Bd3

Better is either 4.Be4+ or 4.Ka6.

4...Kc5 5.Kb7 Kd6 6.Kb6 Ke7

6...Kd5 resists longer.

7.Kc6 Kf6

7...Ke6 resists longer.


8.Kd6 is better. Centralization is a good general concept, but should not supplant concrete analysis.


8...Ke7 is more stubborn.

9.Ke5 Ke7



10.Bc4 is more accurate.



11.Kf6 Kg8

White to move

Black's king is on the edge and seeking refuge in the corner where checkmate is impossible without a dark-squared bishop. White's king is optimally placed, as is White's bishop. The knight must go to f7 to evict the king. In Neff's video, the knight gets to f7 via g5. Objectively, there is no difference between g5 and d5, but as a practical matter, it is worth remembering that the knight wants to be on the center square that is two spaces diagonally from the wrong corner. In some cases, the knight might take up this position before the bishop is posted on its ideal diagonal.

12.Ne5 Kh8 13.Nf7+ Kg8 14.Bg6

Here, in his video, Kevin states that the bishop "improves its position" ("Chess Endgames -- Bishop and Knight, Part 1"). Nonsense. The point of the bishop's move is to lose a tempo without altering the position.

14...Kf8 15.Bh7 Ke8

We have reached the position with the colored W near the top of this post. The letter W highlights the route the knight will take through the course of the second phase. Rensch offers a useful principle, "lead with the knight, follow with the king."

16.Ne5 Kd8 17.Ke6 Kc7

White to move

This was the point where I failed on the second day, earlier this week. As panic set in, I struggled to find a route to Pandolfini's position (after move 4 in "Transition to the Lock"). But, there is another lock available.

18.Nd7 Kb7

White to move


This move completes the lock by covering the squares highlighted in yellow.

19...Kc6 20.Bc4 Kc7 21.Bd5

21.Bb5 pursues Pandolfini's "transition to the lock", which also works.

21...Kd8 22.Kd6

Black to move

We have a sitiuation identical in all its particulars to one that existed two squares to the right after evicting Black's king from the wrong corner. Here, the same maneuver as before drives the king back in the direction we wish.

22...Ke8 23.Be6

Losing a tempo.

23...Kd8 24.Bf7

Denying Black's return to the e-file.

24...Kc8 25.Nc5

The knight reaches the third point of the W. White repeats the process--knight moves, king follows, bishop either loses a tempo or cuts off the escape.

25...Kd8 26.Nb7+ Kc8 27.Kc6 Kb8 28.Kb6 Kc8 29.Be6+ Kb8

White to move

Now, the third and final phase. It is checkmate in four. White's only difficulty is easily solved. The knight must check the king on g8 without blocking the bishop's control of the long diagonal. Two squares are available: d7 and a6. However, d7 would allow the king to return to c8. If we had this position with Black to move, then the bishop could check first and the knight deliver checkmate from d7.

30.Nc5 Ka8 31.Bd7 Kb8 32.Na6+ Ka8 33.Bc6# 1–0

23 May 2017

Seeing Patterns

Tal's Winning Chess Combinations (1979) has influenced my perception. Last week, I read the first chapter of this book by Mikhail Tal and Victor Khenkin, which exists under several titles with and without Tal's authorship. This chapter concerns the rook and corridor checkmates and checkmate threats. These corridor vulnerabilities are most often back-rank weaknesses, but there are other corridors, including a position where a rook must be given up to avoid checkmate between two walls of pawns alongside the f-file.

The large number of deflection combinations to threaten checkmate has made me more alert to these possibilities when going through other games. Of course, these ideas are not new to me. I was familiar with the idea even before Lev Alburt's Chess Training Pocket Book (1997), which I read fifteen years ago, stimulated my imagination for the maneuvers with this exercise.

White to move

Alburt gives the exercise the title, "Defection Detection". It is number 93 in the book.

This morning, I was reading Baskaran Adhiban's annotations to his draw against Wesley So at the Tata Steel Chess Tournament in January when the deflection motif jumped into my perception. After 25.Bxa7, So could have played 25...Rxa7. He did not, playing 25...Bxc3 instead.

What if he had grabbed the bishop?

White to move

Immediately, I saw 26.Qd5+ Kh8 27.Qxe5. However, nothing compels the suicidal 27...Rxe5. So would have had choices: 27...Raa8, 27...Qb6+, and others. In Adhiban's case, his offer of a bishop wins So's bishop, but no more. The game, as he points out, was, "[a]n exciting draw with lots of interesting twists!" (Chess Informant 131, 49).

22 May 2017


In a blitz game this morning, I had an uh-oh moment. Either I was losing my queen or a bishop. I spent 21 seconds contemplating the position, and reasoned that I had compensation for the queen. Then, in the complications, my opponent faltered. I missed some quicker checkmates, but maintained a clear advantage while pressing the attack against a vulnerable king. Most of my opponent's pieces were spectators.

Stripes,J (1845) -- Internet Opponent (1809) [D07]
Live Chess Chess.com, 22.05.2017

1.d4 d5 2.Nf3 Nf6 3.c4 Nc6 4.Nc3 Bg4 5.Ne5

5.cxd5 seems better. One hopes that I will be prepared to make this capture when appropriate should I reach a similar position OTB.

5...Nxe5 6.dxe5 Nd7

6...d4 7.Nb1 Ng8 8.Qb3 Bc8 9.Nd2 e6 Portisch,L (2575) -- Hermann,M (2405), Bad Woerishofen 1992 and drawn in 56 moves. Both players' anti-development highlight the lack of coordination of their pieces.


7.Qd4 Bf5 8.cxd5±

7.Qxd5 c6 8.Qd4 Be6 +=

7.cxd5 Nxe5 8.Qd4 f6 9.Bf4 Bc8±

7...dxc4 8.Qa4 Be6 9.e4 c6

It is clear that winning the pawn on c4 is no easy matter.

10.Rd1 Qb6

10...b5 and Black's pawn in secure.

11.Rd2 g6?!

11...Nc5 12.Qa3 Nd3+ 13.Bxd3 cxd3 14.0–0=

12.Bxc4! Nc5

White to move

13.Bxe6 (box) Nxa4 14.Bd7+ Kd8 15.Bxc6+!?

15.Bh3+ forces a draw 15...Ke8 (15...Kc7 16.e6+ Kc8 17.exf7+ e6 18.Bxe6#) 16.Bd7+=.

15...Kc7 16.Bxa4 (box)

Black to move


16...e6 was the only move, with a slight edge for Black.

17.Nd5++- Kc8 18.0–0 Bg7

18...b5 19.Bb3+-.

19.Rc1+ Kd8

White to move


Perhaps the seventh best move, but easily winning, as Black has two legal moves. One leads to checkmate on the move. The other returns the queen.

I missed the forced checkmate in eight: 20.Nc7+ Kc8 (20...Qd6 21.Ne6+ fxe6 22.Rxd6+ exd6 23.Bg5+ Bf6 24.Bxf6#) 21.Nxe6+ Kb8 22.Nd8 a5 23.Rd7 Rxd8 24.Rxd8+ Ka7 25.Be3+ b6 26.Rc7+ Ka6 27.Rxa8#.


20...Qd7 21.Rxd7#

21.exd6 Bxf6

Black walks walks into checkmate in six.

21...exf6 22.Rc7+-.

22.dxe7+ Kxe7 23.Rd7+

23.Bd6+ leads to a faster checkmate, and also demonstrates understanding of bishops and rooks cooperating. 23...Ke6 24.Bb3+ Kd7 25.Ba3+ Bd4 26.Bxf7 g5 27.Rxd4#.

23.Rc7+ Kf8 (23...Ke6 24.Rd6#) 24.Bh6+ Bg7 25.Rdd7 Bxh6 26.Rxf7+ Kg8 27.Bb3 Rd8 28.Rf6+ Rd5 29.Bxd5#.


White to move

Black walks into a checkmate in three.

23...Ke8 was more stubborn 24.Rxb7+ Kf8 25.Rcc7 g5 26.Rxf7+ Kg8 27.Rxf6 Rf8 28.Rxf8+ Kxf8 29.Bd6+ Kg8 30.Bb3#.

24.Rxb7 Be7 25.Rc6+ Bd6 26.Rxd6# 1–0

21 May 2017


An appalling number of chess games are lost (and won) because a player puts a piece where it is free for the taking. Chess players use the term en prise, which no one in America pronounces correctly, when a piece is within grasp (see Edward Winter, "En Prise [Chess Term]," History Notes, updated 28 February 2015). In Essential Tactics: Building a Foundation for Chess Skill (2017), where I define such terms, I offer the following simple exercise to introduce the idea.

White to move

Such positions often arise from blunders. In a comic blitz game yesterday, it seems that neither player was looking at the board.

Black to move

Black has an extra pawn and a slightly more secure king. However, Black threw the game away with a foolish check that leaves his queen en prise.


However, White did not snatch the free queen, even though his own queen was also undefended.


Evidently Black then noticed that the queens were in contact because he defended his queen.


Finally, White awoke and removed the offending queen.

28.Qxg4 hxg4

A few moves later, White won back the pawn. Nonetheless, he lost after a long battle that both players might wish to forget.

When I think of blunders, I often remember a game that I played fourteen years ago. It was my only standard rated loss to Jim Waugh, against whom I am 10-1-1. Including rapid games, my record reflects two additional losses: 25-1-3. We have played many casual games as well, and he has won a few of those. This loss in the 2003 Inland Empire Open, however, was painful, and remains fresh in my mind. I have a clear and relatively easy win.

Black to move

Inexplicably, I played 22...Re3, thinking to drive the queen from defense of his vulnerable king. Once he had the upper hand, Waugh did not let up.

16 May 2017

Develop Your King

In one of my many blitz games this morning, I had one of those many experiences when I realized that I was playing poorly and now seemed to be losing material.

Stripes,J (1806) -- Internet Opponent (1852) [D06]
Live Chess Chess.com, 16.05.2017

1.d4 d5 2.c4 Nf6 3.Nc3 Bf5 4.Bf4 e6 5.Nf3 Nc6 6.e3 Nb4

White to move

In my despair, I remembered the words of Wilhelm Steinitz:
[W]e consider it established that the king must be treated as a strong piece both for attack and defence. This means that so far from requiring great protection early in the game a few simple precautions which we shall further explain, will render him so safe that any attampt at attacking his wing will be more dangerous for the opponent than for himself.
Wilhelm Steinitz, The Modern Chess Instructor (1889).
Steinitz was concerned with the king's role in self-protection on the king's side, when the king itself is the target. My opponent was angling for my rook, winning an exchange.

7.Kd2! Bc2

My opponent might have tried 7...Ne4+ 8.Nxe4 dxe4 9.Ne1 (9.Ne5? f6)

8.Qc1 Ne4+ 9.Nxe4 dxe4 10.Ne1

Black to move 


10...Ba4 seems to be a better effort to take advantage of the king in the center.

a) 11.a3 Nc6

11...Nd3 is as in the game 12.Nxd3 exd3 13.Bxd3 f6 White has a one pawn advantage.

a1) 12.Bg3 (12.Qc3 e5 appears dangerous). 12...e5 13.d5 Na5 and White is losing at least an exchange.

a2) Nc2

b) 11.b3 is probably safest.

11.Nxd3 Bxd3 12.Bxd3 Bb4+ 13.Ke2 exd3+ 14.Kxd3

Black to move

14...0–0 15.a3 Be7 16.Rd1 f6 17.Ke2 Qe8 18.Bg3 h5 19.h4 and I went on to win the endgame.

14 May 2017

Play as Philidor

As may be well-known, François-André Danican Philidor asserted, "pawns are the soul of chess." In Analysis of the Game of Chess (London, 1790), he developed this idea with a number of games showing pieces standing in the rear so as to support a group of pawns that decide the game. Yesterday, as I was beginning to come out of a blitz slump that lasted three days, I played a game of which Philidor would approve.

White to move

Stripes,J (1897) -- Internet Opponent (1842) [A43]
Live Chess Chess.com, 13.05.2017


26.Qh6 decides matters more quickly.

26...g6 27.h4 Qe6 28.Qg3

The computer likes 28.Qxe6, but the resulting rook ending is a crap shoot in blitz. Both players have chances as blunders are inevitable.

28...Kg7 29.h5 Rh8

White to move


30.d5 Qe4 31.Re5 Qd3 32.f4


30...f6 gives Black good chances to hold. Too often, I overlook these sorts of moves in blitz.


A good move, but not best. Even so, White's pawns are starting to roll per the prescriptions of Philidor.


31...Qf6 32.e4

32.f4 would have demonstrated understanding of Philidor, who preferred that three pawns march together whenever possible. 32...Rh6 33.f5 Rf8 34.d6.

32...Rh6 33.e5 Qf7 34.e6 Qe7

34...Qf6 35.f4 (35.Re5).

35.Qe5+ Qf6

White to move


36.f4 Rch8 37.Kf2 Rh4 38.Kg3


36...Kf7 forces White to struggle.


The pawns will decide.

37...Qxe5 38.Rxe5 Kf6

38...Reh8 makes a threat that I was cognizant of, although in blitz I overlook such things often enough. 39.f4 (39.e8Q Rh1#).

39.Re2 Rhh8

White to move


40.Rfe1 is stronger 40...Kf7 41.d7


40...a4 41.Rxb6 Kf7 42.Rb4 Rc8 43.Re1 Rce8 44.d7

41.d7 1–0

Black's two rooks must go away to eliminate White's two queens.

12 May 2017

Imbalances and Planning

Years ago, I read Jeremy Silman, How to Reassess Your Chess, 3rd ed. (1993). The book offers useful instruction concerning imbalances and planning. However, sometimes in blitz, I play as if I am in utter ignorance of how to assess a position. Instead, I play for simple cheapos that are easily refuted.

This position from a blitz game offers a case in point.

White to move

I played 21.g5, hoping for 21...hxg5 22.hxg5 and thought that somehow my rooks could penetrate. Not only is there no clear tactical breakthrough, but it's not entirely clear that I should seek exchanges on the kingside.

How should White play here?

11 May 2017

Elementary Checkmate

There is nothing difficult about this checkmate in two, but it is notable. This position arose in a blitz game this morning. Much of that game resembled a correspondence game that I won two years ago (see "Beating a National Master"). White's kingside pawn storm, including the pawn sacrifice was similar, as was the resulting Black pawns on g7 and g6. Again, my king was able to find refuge on f7, temporarily.

Black to move

The simple checkmate in two was included in my book, Forcing Checkmate, which I wrote in March.