Making my Point

In "Bishop and Knight Checkmate," I offered some mild criticism of Kevin at thechesswebsite.com. In his YouTube video teaching checkmate with bishop and knight and repeats the phrase, "it doesn't really matter," as he emphasizes general concepts. He communicates to his viewers that moves grounded in calculation or memorized patterns are less important than general concepts.

There are three steps or phases in this checkmate.

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

General principles--centralizing ones pieces and coordinating them--do prevail in the first phase, but failure to calculate runs risks. Last night, I spent a few minutes continuing my practice of this checkmate. I started from one of the exercises that I created for my series, Essential Tactics. Two books containing these exercises are available through Amazon: the eBook Essential Tactics: Building a Foundation for Chess Skill contains the exercises and solutions; the paperback Essential Tactics: The Worksheets is designed for teachers wishing to use my worksheets with their students.

White to move

The tactic here is a simple skewer that wins the Black queen by promoting the pawn to a queen or bishop. Naturally, promotion to a queen is the sensible and correct move, unless one is seeking practice checkmating with bishop and knight.

In the course of my practice, I made many moves that tablebases reveal to be the best possible. Often there are several different moves that lead to checkmate in the minimum number of moves. However, I made several moves that were short of perfection. One move added six to the number required to bring about checkmate. Two missteps of this magnitude would have awarded the computer a draw by the fifty-move rule.

Stripes,J -- Stockfish for iPad
29.05.2017

1.h8B+ Kc5 2.Bxb2 Kb4 3.Nf3 Kc5 4.Kg2 Kb4 5.Kf2 Kc5 6.Ke3 Kb4 7.Bd4 Kb5 8.Ne5 Ka6 9.Ke4 Kb7 10.Kd5 Kc7 11.Kc5

11.Nc4 is better. Why? The knight needs to prepare to move to c7 in order to evict the king from a8. The king wants to move to c6. But, perhaps these plans are getting a bit ahead of the position. Black's king is not yet on the edge. These squares are vital for the second phase; the game is still in phase one. It is not easy to determine why 11.Nc4 is best. Tablebases indicate that it is the only move leading to checkmate in 23 moves, while 11.Kc5 is one of seven options that lead to checkmate n 24 moves.

11...Kb7

White to move

12.Ng6

12.Kd6 is one of three choices that lead to checkmate one move faster than 12.Ng6. I thought that I had found a clever route to d5, where the knight can reach c7. But, again, this stage of the game is still the first step--driving the king to the edge.

12...Kc7 13.Ne7 Kd7 14.Nd5 Ke6

White to move

We see the consequences of carelessness. My efforts to prematurely play the second phase have unnecessarily extended the first. Now, I have a single move that keeps matters under control. I failed to execute it.

15.Kc6

15.Ne3 leads to checkmate in another 20 moves. With my move, I  am further from the finish of this game than I was on move 11. There is a principle of piece coordination that might have helped me to see my way through the fog: keep the knight on the same color square as the bishop.

15...Kf5 16.Nc3

16.Nf6 takes away e4 and g4 from the king. Black's king is forced to the edge after the subsequent moves 16...Kf4 17.Kd5 Kf3 18.Ke5 Kg3 19.Ke4 Kg2 20.Kf4.

16...Kg4 17.Kd5 Kf4 18.Ke6 Kg5 19.Ke5 Kg4 20.Ke4 Kg3 21.Be3 Kg2

White to move

22.Kf4

22.Ne2 forces the king to the edge, and prepares to move the knight to g3, where it evicts the king from h1. My move also forces the king to the edge. This was the correct point in phase one to think about optimal piece placement during the second phase.

22...Kh3 23.Kf3 Kh4 24.Kf4

I should have recognized the position after 24.Ne4. 24...Kh5 25.Kf4 Kg6 26.Ng5 Kg7 27.Bc5.

24...Kh3 25.Ne4 Kh2 26.Kf3 Kh1

White to move

Now, I feel that I understand what I am doing. Having extensively practiced phase two over the past few days, it has become routine.

27.Ng3+ Kh2 28.Bf2 Kh3 29.Bg1 Kh4 30.Ne4 Kh5 31.Kf4 Kg6 32.Ng5 Kg7 33.Bc5 Kf6 34.Bd6 Kg6 35.Be7 Kh5

White to move

36.Kf5

36.Nf7 is faster per the method I had learned from Bruce Pandolfini. 36...Kg6 37.Ne5+ Kh5 38.Kg3. It is good to remain flexible.

36...Kh4 37.Bd6 Kh5 38.Bg3 Kh6 39.Ne6 Kh5 40.Ng7+ Kh6 41.Kf6 Kh7 42.Kf7 Kh6 43.Bf4+ Kh7 44.Ne6 Kh8 45.Bg5 Kh7 46.Nf8+ Kh8 47.Bf6# 1–0

Checkmate with knight and bishop took me 45 moves after the last capture. I can do better. Surely, it does matter how one plays the pieces during the first phase of this checkmate. That was my criticism of Kevin. My own errors last night make my point.

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.Kd5

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

8...Kf7

8...Ke7 is more stubborn.

9.Ke5 Ke7

9...Kg7

10.Bf5

10.Bc4 is more accurate.

10...Kf8

10...Kf7

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

19.Bd3

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

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).

Uh-Oh!

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.Bf4?

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...Qe6?

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

20.Nf6+

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...Qd6

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#.

23...Ke6

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

Blunders

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.

26...Qg4+??

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

27.Kf1??

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

27...h5??

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.

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...Nd3

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.

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.Qg4

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.hxg6

30.d5 Qe4 31.Re5 Qd3 32.f4

30...fxg6?

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

31.d5

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

31.f4!

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.e7?

36.f4 Rch8 37.Kf2 Rh4 38.Kg3

36...Re8?

36...Kf7 forces White to struggle.

37.d6+-

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.Rb1

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

40...Rb8

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.

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?

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.

More of the Same

In my Knight Award exercises, I include a position from Horvath -- Vigus, Haarlem 1998.

White to move

This exercise was part of my lesson of the week just before the winter holiday last December, where it was paired with a similar position from one of my online blitz games (see "Pattern Training").

This morning, while reading an old classic that I acquired yesterday, I found a similar position.

White to move

This position is given as Gutmatyer -- Sviderski 1928 in Mikhail Tal, and Victor Khenkin, Tal's Winning Chess Combinations, trans. Hanon W. Russell (1979). I failed to locate this game in any of my databases.

White played 1.Rc1, and then missing the checkmate threat, Black blundered with 1...Qxe5. Tal and Khenkin observe that 1...Qd3 was Black's correct response.

Breaking Down Tactics

Some tactics training sessions are long; others short. Yesterday morning, I attempted three problems on Tactic Trainer on my iPad. This app, which sells for $2.99, is one that I have used off and on for several years. As the database of problems are stored on my device, it is useful when I go off the grid--away from internet service. Using this app a few years ago on a fishing trip, I was able to spend three hours solving exercises while making coffee and breakfast for everyone. I reviewed this app in "Chess Tactics Training on the iPad" (February 2013).

I cut yesterday's training session short because it seemed necessary to review. I solved the first problem quickly and correctly. What did I do right? How did I see the combinations? It is worth breaking the problem down to understand what I saw and understood in a matter of seconds. I failed the second problem by choosing the wrong second move. My move was clearly winning, but there was a better move. Was I hasty or shallow in my thinking? The third problem was another success, but I thought that the twenty to thirty seconds I used was unreasonably long for such an easy problem. Why did I require so much time?

One drawback of this app, in contrast to ChessTempo, Chess.com's tactics, and similar training tools on several other websites, is that it does not record my solving time.

Black to move

1...Qxd3!

Instantly I saw that Black attacks the knight twice and White defends it twice. That alerted me to a possible tactic if the king could be driven away after an exchange on d3. It took a few seconds to see Black's control of d2 and e1 with the bishop, and also to see the possibilities of thrusting the f-pawn forward. Is the rook on f8 necessary to the combination? It is.

2.Qxd3 f3+ 3.Kf1

3.Qxf3 is also possible, and that reveals the importance of the rook on f8. 3...Rbxf3. I recall calculating also 3...Rfxf3 and observed that both the bishop and rook cover f8 to meet 4.Rc8+.

3...Rxd3

Black has won a bishop.

It seems that quickly recognizing the deflection tactic was the key to solving this exercise. Some calculation was necessary as well.

White to move

1.Nxf6+

The first move was obvious, as the exchange either decoys Black's queen into a pin or removes the defender of the knight.

1...Qxf6 2.gxf4

I chose 2.Nf3 and failed. I overlooked 2...h6, although then White is still winning and still has 3.gxf4, although 3.Rg1 is better. I saw one pin, but missed possible pins on the g-file.

Acoording to my computer, the best line continues 2...Qxf4 3.Bxg5 Qe4+ 4.f3. I do not know how far the exercise would have extended had I played 2.gxf4.

What causes me to see one pin and miss another? What causes me to overlook 2...h6? Distraction and haste could be factors. I solved this exercise quickly. Also, in the morning during coffee time, my wife and one or more dogs are with me in the living room. But, I think there is something else. Something curable through training.

Black to move

1...Rg1+ 2.Kxg1 Qh1#.

This problem was easy, and I solved it correctly. However, I first started calculating lines that begin 1...Qh3+ and also glanced at 1...Bh3+. It became clear that these lines did not produce checkmate quickly. Only when these lines appeared futile, did I see the correct solution. That may have been after twenty seconds, or it may have been as long as a minute.

As in the previous exercise, I saw a move that looked good and began to pursue it. In both cases, there was a better move. In the third exercise, I found the better move before making my move. In the second exercise, I played a good, but not the best move.

It is good to remember the adage frequently attributed to Emanual Lasker, and pushed back a few years by a reference on Wikipedia, "When you see a good move, look out for a better." As an historian, I must point out that Domenico Ponziani should be credited with the saying.

[I]t is necessary always to bear in mind these prudential rules, viz.: having a good move, to seek for a better; having a small but certain advantage, not to risk it for a greater but uncertain one. Dominico Ercole del Rio, The Incomparable Game of Chess, trans. J.S. Bingham (London 1820), 35-36.

Bingham incorrectly attributes this work by Ponziani to Ercole del Rio, as is pointed out in "Domenico Lorenzo Ponziani," The Chess World, vol 2 (1867), 327-336, an article reprinted from American Chess Monthly.

As a chess student, these historical forays chasing footnotes are less critical than the advice itself. Through three exercises yesterday, I have identified an area to work on: flexibility in calculation. Seeing one pattern, I need to remain alert to others. When I do my tactics exercises, I must slow down. Parts 3 and 4 of David Pruess's video series, "4 Exercises to Become a Tactical Genius," offer suggestions for exercises that specifically address these calculation errors.

The Polgar Brick: eBook Edition

A Review

Chess: 5334 Problems, Combinations, and Games by László Polgár contains 306 checkmate in one, 3412 checkmate in two, 744 checkmate in three, and then 600 miniature studies. These miniatures (game of 25 moves or less) are sorted into six groups. Each group contains 100 games that featured a sacrifice on one of a pair of squares--f3.f6, g3/g6, h3/h6, f2/f7, g2/g7, and h2/h7. I described one of the ways that I found this section useful in "Building Upon Morphy". Following the miniatures section are 144 simple endgames and then 128 combinations from the Polgár sisters, Susan, Sophia, and Judit. Susan and Judit are Grand Masters, and Judit was in the FIDE top ten a few years ago. Sophia, who was more interested in art than chess, is an International Master.

The book was first published by Könemann in 1994 under the title Chess in 5333+1 Positions. The "+1" in the original title reflects the distinctiveness of the final position, an artistic checkmate in two composition by Sophia. In 2006, Black Dog & Leventhal brought out a new edition that is approximately half the size--same thickness, but 6 x 9 inches instead of the large 8 x 12 format. I have the Könemann paperback edition, which I bought for $25 in 1998. The smaller edition is still a large book, although considerably lighter than the original. At some point, this book acquired the nickname "Polgár Brick" in several social media forums. Both editions are 1104 pages.

The Black Dog & Leventhal edition added an introduction by Bruce Pandolfini, while eliminating front matter in languages other than English. The Könemann edition has the table of contents, Polgár's forward, and other material in ten languages.

It is a useful book for self-study and useful to chess teachers, but it is awkward to carry in a backpack. Last week, I bought the Kindle eBook edition for $2.99 and now have the book on my iPhone and iPad. Hence, I always have it with me unless I am swimming.

Fifteen years ago, I spent 20-30 minutes per day with this large book during my morning coffee. I would solve each exercise looking at the diagram and write down my answer on a piece of paper. Then, I would check the answers in the back of the book and record the percentage that I got correct. When this percentage was below 90, I would rework the problems a few days later. Over the course of a few months, I solved the first 1596 problems. Since then, the book has mostly sat on a bookshelf alongside other neglected books. Occasionally, I would pull it off the shelf when looking for some instructive checkmate exercises for students or to work through some of the book's miniatures.

Even strong players capable of solving difficult tactics problems could benefit from working through the checkmate in one exercises. The first 156 contain a minimum number of pieces. Beginning with number 157, the board is crowded with pieces. How many can you solve as fast as you turn the page? I found that I could solve the first 156 instantly, but then slowed down. Some took a few seconds; others were as easy as those with few pieces. Solving these exercises quickly and repeatedly should improve board vision and pattern recognition.

Some of the ckeckmate in two exercises are challenging, depending on your skill level. But, they are intended by Polgár to require only a few minutes and to build the reader's confidence. Naturally, the checkmate in three are more challenging, but still not horrendously difficult.

In the print edition, there are six problems per page. The eBook presents one per page. In the solutions, the composer is indicated if is was not Polgár. For the checkmate in one (naturally) and the checkmate in two, only one move is given. The solutions to the checkmate in three are carried out to checkmate. In the eBook, the problem number is a hyperlink to the solution and the number above the solution links back to the problem.

Only a few of the first 4462 positions are from real games. The 600 miniatures, of course, are all real games, as are 127 of the 128 from the Polgár sisters.

The eBook edition extends the usefulness of this book. It is certainly much easier to carry, as noted above. There are a few formatting issues, but these serve only as distractions and do not mar the book's usefulness. Some of the solutions seem to be in a larger font, for example. In the bibliography at the end of the book, the Russian language sources listed are in a smaller font than the other texts.

Now that I have the eBook, I expect to make much more extensive use of the miniatures section. Last fall, I carried the mammoth book to a chess lesson with a student so that we could look at a few of the miniatures together. Then, it sat on the floor of my car for most of the winter. No longer. The book need not leave my house, and I will always have it during chess lessons. I rarely do not have my iPad and never leave my home without my phone.

Print Edition First Miniature

In the book, the miniatures contain the early moved of the game, then a diagram with the critical position. Underneath the diagram is the conclusion of the game. This is the same structure that one finds in the Encyclopedia of Chess Miniatures (2015). Ideally, the student would look at the diagram and solve the position without looking at the continuation below. This exercise is most easily accomplished by covering the moves below with a scrap of paper.

eBook Edition First Miniature

In the eBook edition, the initial moves and diagram are on one page, and the game's conclusion is on the next page. That structure makes it more useful as a training tool than the print edition and the cost is slightly more than 10% of the publisher's list price.

If you do not have this book, it might be time to download the free Kindle app and enter the world of chess eBooks. There are many exceptional chess books in this format. Few are as good of a bargain as the Polgár brick. Do be careful, however, there are chess eBooks that are complete rubbish. Some are even written by people who do not know how to play chess (see "Kindle Chess Books").