26 April 2017

One from Greco

The oldest English language book that presents games from Gioachino Greco (c.1600 - c. 1634) is Francis Beale, The Royall Art of Chesse-Play (London 1656). This book contains 154 games attributed to Greco, as well as examples of Fool's Mate and Scholar's mate. This number of 154 exceeds the 77 Greco games that one can find in databases and at sites such as chessgames.com because the variations were reduced to those Angelo Lewis considered the main games. Angelo Lewis (1839-1919) wrote under the pseudonym Professor Louis Hoffman. His The Games of Greco (London 1900) is the basis for those found in David Levy, and Kevin O'Connell, Oxford Encyclopedia of Chess Games, vol. 1, 1485-1866 (Oxford 1981), which in turn became the source when databases were created.

In between Beale and Hoffman, William Lewis (1787-1870) produced an edition of Greco's games, Gioachino Greco on the Games of Chess (London 1819), which was based on a French edition of Greco's games. In Lewis, Greco's games are 168 variations of 47 games.

In Beale's book, the games are called "Gambetts" and numbered with roman numerals. The first game in the book is also in Hoffman and the Oxford Encyclopedia, but the final move differs.


Gambett I (Greco) [C23]
Beale 1656

1.e4 e5 2.Bc4 Bc5 3.Qe2 Qe7 4.f4 Bxg1 5.Rxg1 exf4 6.d4 Qh4+ 7.g3 fxg3 8.Rxg3 Nf6 9.Nc3 Nh5 10.Bxf7+ Kxf7 

White to move

11.Bg5 Nxg3 12.Qf3+ Kg6 13.Bxh4 Nh5 14.Qf5+ Kh6 15.Bg5#

15.Qg5# is given in ChessBase per Hoffman; Levy, and O'Connell; and Lewis.

1–0

This game is in Lewis 1819, 70; Hoffman 1900, 110; Levy, and O'Connell 1981, 4; and Beal 1656, 18-19.

My eBook, Essential Tactics: Building a Foundation for Chess Skill (2017), contains a composed position that I derived from the diagram position above.

White to move

My method in creating that book was to take positions from actual games and typical structures that might occur in games, and then strip away the extraneous pieces. I made such modifications necessary that in most cases there is one clearly best move, and often only one winning move (or drawing move in certain cases).


25 April 2017

How Easy?

I created this exercise four years ago for my students. It is one of what I call "one-move worksheets". I create a single page of four to nine exercises that I am able to photocopy for my chess students. I have made some of these worksheets available to other coaches.* Some have been collected and gathered into two books that I self-published through Amazon. Essential Tactics consists of 150 exercises with ten pieces or fewer. Forcing Checkmate contains 160 exercises leading to checkmate.

This position is number 82 in Essential Tactics. Every time I look at it, I worry that White cannot win, but that it should be drawn. Some of my exercises do lead to draws, but not this one.

White to move

This morning, I played the position out against Stockfish and checkmated the silicon beast in 29 moves. I think that I might have won a couple of moves faster if I had calculated a little better. One imprecise move was immediately obvious to me after I made it in haste.


*Use the contact form to the right if you are a coach with interest in my teaching materials for your use.

21 April 2017

Tactics: Basic and Advanced

Lesson of the Week

Bobby Fischer has been my theme this week. Most of my students have seen various positions derived from his brilliant win against Donald Byrne at the Rosenwald Trophy Tournament in New York, 1956. The whole game is posted at "Byrne -- Fischer, New York 1956". The students in my advanced club did not have difficulty finding the smother checkmate that might have occurred, but struggled to work out the game's finish without moving the pieces.

Black to move
After 18.Bxe6 (not played)
 Black to move
After 36.Kf1
Fischer found a checkmate in six, but there was one in five. Either would be acceptable if my young students could describe the sequence in chess notation without moving the pieces.

Students in my clubs were also presented with the worksheets Essential Tactics 7-10. There was no expectation that they would complete all four, but only the suggestion that they spend fifteen minutes solving exercises before playing chess.

These exercises are extracted from my eBook, Essential Tactics: Building a Foundation for Chess Skill (2017). Originally created four years ago as the worksheets Beginning Tactics 1-18, I have revised them as Essential Tactics 1-25. The same 150 exercises are on the worksheet sets and in the book. However, the first set of worksheets used chess pieces in some of the diagrams that the students found confusing. I switched all to the pieces ChessBase calls Fritz (used in the diagrams in the post). The number of worksheets increased in the revised set because each sheet contains six exercises. In the original series, worksheets 5-18 had nine exercises each.

To my surprise, my top second grader struggled with this exercise.

White to move

A few of the exercises on Essential Tactics 10 get to the core of finding two move combinations.

White to move

White to move

20 April 2017

Creating the 300

In GM-RAM: Essential Grandmaster Knowledge (2000), Rashid Ziyatdinov offers his version of the legendary 300 positions that a player must know to become a strong chess player. I have written about this book on several prior occasions, especially "Hitting the Books" (March 2015); "The Training Standard" (January 2015); "To Know a Position" (December 2014); "Morphy's Fingerprints" (December 2014); "Fingerprints" (April 2010); and my initial review of the book, "GM-RAM: Essential Knowledge" (February 2010).

Ziyatdinov leaves 47 of the 300 to the reader. I am tentatively and slowly adding critical positions from my study in search of 47 that matter to me. I have so far added:

Alekhine -- Levenfish 1912

White to move
After 14...Qxb2
Carlsen -- Tomashevsky 2016

White to move
After 12...Ng6
Byrne -- Fischer 1956

Black to move
After 11.Bg5

19 April 2017

Byrne -- Fischer, New York 1956

"Game of the Century"
It was quite an experience to watch [Bobby Fischer] during the critical stage of the game. There he sat like a little Buddha, showing his moves with the calm regularity of an automaton.
Hans Kmoch, "Game of the Century," Chess Review (December 1956)
Hans Kmoch, as manager for the Manhattan Chess Club, directed tournaments there. The Third Lessing J. Rosenwald Trophy Tournament took place 7-24 October 1956 at the Manhattan Chess Club and the Marshall Chess Club. Fischer was invited because he had won the U.S. Junior Championship in July, the youngest player ever to do so. The Rosenwald tournament was the first time that he played against the top masters in the United States. His round 8 win against Donald Byrne won the tournament's brilliancy prize and was dubbed the "game of the century" by Kmoch.*

Kmoch wrote that the game, "matches the finest on record in the history of chess prodigies" (Kmoch, Chess Review, rpt. in Bruce Pandolfini, The Best of Chess Life and Review, vol. 1, 1933-1960 [1988], 525).

This game has been annotated many times. For my annotations, I went through the game several times. At several critical positions, I wrote my anticipated variations without moving the pieces. After recording these lines, I checked mine against Garry Kasparov, My Great Predecessors, part IV Fischer (2004). I then checked some of my lines with Stockfish 7.

This game strikes me as a good one for honing a player's calculation skills. It is among my candidates for "best game ever played."


Byrne,Donald -- Fischer,Robert James [D97]
New York Rosenwald New York, 1956

1.Nf3 Nf6 2.c4 g6 3.Nc3 Bg7 4.d4 0–0 5.Bf4 d5 6.Qb3 dxc4 7.Qxc4 c6 8.e4 Nbd7 9.Rd1 Nb6 10.Qc5?! 

10.Qb3 seems better.

10...Bg4 11.Bg5?

11.Be2 seems necessary.

11...Na4!

This move stunned me when I was playing through the game on a chess board last week. On the one hand, it is a simple deflection combined with a threat to remove the guard of the e4 pawn. On the other hand, Black cannot win a pawn, but rather offers an exchange sacrifice. Fischer had to calculate several lines. In all of these, the vulnerability of White's king proved decisive.

White to move

This position was on my board at the dining room table for most of the weekend. I returned to it several times to study and record possible variations.

12.Qa3

Alternatives begin with 12.Nxa4 Nxe4 and then:

a) 13.Bxe7 was the first line I recorded in my notes. 13...Re8 is the computer's second choice (The engine prefers 13...Qc7 14.Bd6 Nxd6) 14.Bxd8 Nxc5+ (Kmoch has this line, but revereses the order of the previous two moves) 15.Be2 Nxa4 16.Bh4 Nxb2 and Black is clearly better.

b) 13.Qxe7 was my second line. 13...Qxe7

My analysis falls short here. The engine prefers 13...Qa5+ 14.b4 Qxa4 15.Qxe4 Rfe8 16.Be7 Bxf3 17.gxf3 Bf8 Garry Kasparov credits Sergei Shipov with this line. Clearly Black is winning.

Continuing my line: 14.Bxe7 Rfe8 15.Be2 (The engine prefers 15.Bd3 ) 15...Rxe7 16.0–0 (The engine prefers 16.h3 ) 16...b5 17.Nc3 Nxc3 18.bxc3 Rxe2 Black is ahead a piece.

c) 13.Qc1 Qa5+ 14.Nc3 Bxf3 15.gxf3 Nxg5 is offered by Kasparov. I did not look at this line.

d) 13.Qb4 Nxg5 14.Nxg5 Bxd1 15.Kxd1 Bxd4–+ Kasparov. Another line that I failed to examine.

My third line continued:

e) 13.Qa3 Nxg5 14.Be2 Nxf3+ (Stockfish prefers 14...Bxf3 15.Bxf3 Qa5+ 16.Nc3 Qxa3 17.bxa3 Nxf3+ 18.gxf3) 15.Bxf3 Bxf3 16.Qxf3 and Black is winning.

12...Nxc3 13.bxc3 Nxe4 14.Bxe7 Qb6

White to move

15.Bc4

What if White accepts the exchange sacrifice?

15.Bxf8 Bxf8 16.Qc1

I also considered 16.Qb3 Qxb3 (Kasparov gives 16...Nxc3, attributing the suggestion to Yuri Averbakh) 17.axb3 Nxc3 18.Rd2 Re8+ 19.Be2 Bb4-+

16...Re8 17.Be2 Nxc3

Analysis diagram after 17...Nxc3
I spent a lot of time trying to find a defense for White here. Instead, I found only lines leading to checkmate or to an overwhelming material advantage for Black.

18.Rd2

(Stockfish prefers 18.Qxc3 Bb4 and there was no doubt in my mind that Black was winning here)

18...Rxe2+ 19.Rxe2 Nxe2 20.Kxe2 Qb5+ 21.Ke1

(21.Kd1 seems best 21...Qd3+ 22.Qd2 Bxf3+ 23.gxf3 Qxf3+ 24.Kc2 Qxh1-+)

21...Bb4+ 22.Kd1

(22.Qd2 Bxd2+ 23.Kxd2 [23.Nxd2 Qe2#])

22...Qd3+ 23.Qd2 Qxd2#

15...Nxc3 16.Bc5

I considered 16.Qxc3 Rfe8 17.0–0 is Stockfish's choice, as it was mine (I did not look at Kasparov's line 17.Bxf7+ Kxf7 18.Ng5+ Kxe7 19.0–0 Bxd1 20.Rxd1) 17...Rxe7 and Black has a clear edge.

16...Rfe8+ 17.Kf1 Be6!!

White to move

18.Bxb6

After the possible 18.Bxe6, I spent a lot of time looking at complex and unclear lines before I saw Fischer's plan: 18...Qb5+ 19.Bc4 Qxc4+ 20.Kg1 Ne2+ 21.Kf1 Ng3+ 22.Kg1 Qf1+ 23.Rxf1 Ne2#.

I also saw 18.Qxc3 Qxc5 19.dxc5 Bxc3 20.Bxe6 Rxe6.

After Fischer's queen sacrifice, the moves seemed rather forcing and I did not look at variations again for many moves.

18...Bxc4+ 19.Kg1 Ne2+ 20.Kf1 Nxd4+ 21.Kg1

I did not examine 21.Rd3 axb6.

21...Ne2+ 22.Kf1 Nc3+ 23.Kg1 axb6 24.Qb4 Ra4 25.Qxb6 Nxd1

White to move

26.h3

I did not examine 26.Qxb7 Bd5 27.Qd7 Re2.

26...Rxa2 27.Kh2 Nxf2 28.Re1 Rxe1 29.Qd8+ Bf8 30.Nxe1 Bd5 31.Nf3 Ne4

Here it seems to me that White is running out of moves. He has not been in the game since capturing Fischer's queen. In fact, he was lost before that. His role is to make the moves that permit the young Fischer to demonstrate his skill.

32.Qb8 b5

Kasparov mentions 32...Kg7.

33.h4 h5 34.Ne5 Kg7 35.Kg1 Bc5+

White to move

36.Kf1

I knew that 36.Kh2 would lose quickly, but my Ra1 is inferior to 36...Nd2!

I saw 37.Qc7 (37.Nf3 Bd6+) 37...Bg1+ 38.Kh1 Nf2#.

36...Ng3+

36...Bc4+? 37.Nxc4.

I found another checkmate as fast as Fischer's: 36...Rf2+ 37.Ke1

37.Kg1 loses faster 37...Rf4+ 38.Kh2 Rxh4#.

37...Bb4+ 38.Kd1 Bb3+ 39.Kc1 Rc2+ 40.Kd1 (40.Kb1 Nc3+ 41.Ka1 Ra2#) 40...Nf2#.

37.Ke1 Bb4+

Kasparov points out a faster checkmate: 37...Re2+ 38.Kd1 Bb3+ 39.Kc1 Ba3+ 40.Kb1 Re1#.

38.Kd1 Bb3+ 39.Kc1 Ne2+ 40.Kb1 Nc3+ 41.Kc1 Rc2# 0–1

After this game, the world noticed Bobby Fischer. Within a few years, he became a leading candidate for a future World Championship match. When he finally reached the summit, he gave up on chess. Of course, there were reasons. He set conditions that were not met wholly.


*For some of the historical details concerning this tournament, I am indebted to John Donaldson, and Eric Tangborn, Bobby Fischer: The Early Years: 1943-1962 (Amazon Digital Services, 2017).



15 April 2017

Lesson of the Week

All of my students this week saw this position with an opportunity to suggest the best move. Many succeeded. Some of my students saw the whole game, which is posted at "Botvinnik -- Capablanca, AVRO 1938".

White to move

13 April 2017

Botvinnik -- Capablanca, AVRO 1938

A Strategic Masterpiece

As one of the most important games from one of the strongest tournaments ever held, it makes sense that Botvinnik -- Capablanca, AVRO 1938 should be highly regarded. The game is deceptively simple, which leads some critics to dismiss it as not worthy of consideration as one of the greatest games ever played. However, it is historically significant--a watershed event in the development of professional chess. It is also a rich strategic masterpiece. Early in the game, both players adopted clear plans that were clear to their opponent. Mikhail Botvinnik's plans succeeded, while Jose R. Capablanca's plans proved too slow.

What accounts for the difference? Surely, Botvinnik did not calculate to the end to realize that his plans were superior. Was his success the result of home preparation? An interesting statement by an unsigned annotator appears at the end of the game in the ChessBase PowerBook database:
Capablanca's resignation, in my opinion, symbolized the end of an heroic era of chess titans, dominating the field with their natural genius. Since this historic moment the professional touch has played a more and more important role as an integral part of chess, the path to ultimate success.
ChessBase PowerBook*
This game is one of two that received a perfect score from the editors of The World's Greatest Chess Games (1998)--Graham Burgess, John Nunn, and John Emms. That was sufficient for me to include it on my list of ten candidates for the "Best Chess Game Ever Played." After last week's Spring Break Chess Camp, I decided to spend more time with these ten games.

Over the past several days, I have repeatedly gone through this game on my iPad and with select students. On Sunday, I sat at the table in front of a chess board and played through the game with Botvinnik's annotations in One Hundred Select Games (1960). Then, I read the annotations in Garry Kasparov, My Great Predecessors, Part II (2003); and in The World's Greatest Chess Games. I also watched videos by Kingscrusher, Jerry at ChessNetwork,  and A. J. Goldsby.

Botvinnik,Mikhail -- Capablanca,Jose Raul [E49]
AVRO Holland (11), 22.11.1938

1.d4 Nf6 2.c4 e6 3.Nc3 Bb4 4.e3

Lots of moves have been tried here, but this remains the most popular. Botvinnik's comment is interesting.
The Nimzo-Indian Defence is not to be refuted in this way, but recent practice has shown that it is doubtful whether there is any refutation.
Bovinnik, One Hundred Select Games, 154.
4...d5

Possibly dubious for reasons made clear in this game.

5.a3

5.Nge2 dxc4 6.a3 Ba5 7.Qa4+ c6 8.Qxc4 0–0 9.Ng3 Nbd7 10.f4 Nb6 11.Qd3 c5 12.dxc5 Qxd3 13.Bxd3 Bxc3+ 14.bxc3 Na4 and drawn in 33 moves. Euwe,M -- Capablanca,J, Amsterdam 1931.

5.Qa4+ Nc6 6.Nf3 0–0 7.Bd2 Bd7 8.Qc2 Re8 9.Rd1 Bd6 10.Bc1 a5 11.a3 a4 12.c5 Bf8 and White won in 57 moves. Eliskases,E -- Ragozin,V, Moscow 1936. One of the games that led to the name and principles of the Ragozin System.

5.Nf3 is the main line 5...0–0 6.Bd3 c5 7.0–0 Nc6 8.a3 Bxc3 9.bxc3 b6 10.a4 cxd4 11.cxd5 Qxd5 12.exd4 Bb7 13.Re1 Rfd8 and drawn in 42 moves, Alekhine,A -- Keres,P, Holland 1938. From the same tournament.

5...Bxc3+

5...Be7 is playable, but Black has given up a tempo to assist White's queenside expansion.

6.bxc3 c5

6...0–0 7.cxd5 exploits the inaccuracy of 4...d5.
6...c6.

7.cxd5 exd5

White has undoubled his pawns, casting doubt on the wisdom of 4...d5.

8.Bd3

8.f3 has become popular.
8.dxc5 was played in the previous game that reached this postion 8...0–0 9.Bd3 Nbd7 10.Ne2 Nxc5 11.Bb1 b6 and Black won in 52 movess, Landau,S -- Keres,P, Zandvoort 1936.

8...0–0 9.Ne2

When I was racing through this game quickly, this was the first move that caught my eye. As I began to understand this game, however, it became clear that this was a vital part of White's overall plan. Botvinnik understood the sort of position in which Philidor's famous advice was apropos. The knight must support and not impede the advance of the e- and f-pawns.

Black to move

Both players have clear middlegame plans rooted in their respective pawn majorities. White will expand in the center and kingside; Black will play on the queenside. In the ensuing battle, White's plan proves to be faster.

9...b6 10.0–0 Ba6 11.Bxa6

Giving up the bishop pair may seem odd, but this move gains a tempo or two.

11.Bc2 Botvinnik suggested that maybe he "should have" retreated the bishop (154), but it is worth noting that doing so did not work out so well for White two years earlier. 11...Nc6 12.Re1 Re8 13.f3 Rc8 14.dxc5 bxc5 15.Ng3 d4 16.exd4 cxd4 17.Rxe8+ Qxe8 18.cxd4 Nxd4 19.Ba4 Qe5 20.Rb1 Nd5 21.Bb2 Nc3 22.Bxc3 Rxc3 23.Kh1 h5 24.Bd7 Rd3 25.Qa4 Bb7 26.Ne4 Bxe4 27.fxe4 Nf3 0–1 Stahlberg,G (2531) -- Keres,P (2567), Bad Nauheim 1936.

11...Nxa6 12.Bb2?!

An inaccuracy, according to Botvinnik.

12.Qd3, provoking Qc8 was better.

12...Qd7!

Capablanca understands the light-squared battle ahead. This move also threatens penetration on the queenside.

13.a4

Necessary to prevent Qa4.

13...Rfe8?

"A surprising mistake for Capablanca to make" (Botvinnik, 155).

13...cxd4 14.cxd4 Rfc8 and Black is slightly better. "White would probably have sufficient resources available for his defence" (Botvinnik).

14.Qd3 c4? 15.Qc2

Black to move
Yellow, as in the game; or green (my suggestion)?

15...Nb8

Knowing how the game concluded makes it easier to find fault with Black's plan.

I like 15...Nc7 with the idea of employing the knight in defense.

16.Rae1! Nc6 17.Ng3 Na5 18.f3 Nb3 19.e4 Qxa4 20.e5 Nd7 21.Qf2 

21.f4? produces a useful tactics exercise

Black to move (analysis diagram)
21...Nbc5! 22.Qe2 Nd3 23.Rb1.

21...g6 22.f4 f5

Another exercise from this game. Does the student understand the strategic requirements of the position?

White to move

23.exf6

The only chance for an advantage.

23...Nxf6 24.f5 Rxe1 25.Rxe1 Re8

Yet another useful training position. I played out this position with a student on Monday. His 26.fxg6 presented some challenges at the rapid pace that we played. It does seem inferior to Botvinnik's move, however.

26.Re6! Rxe6 27.fxe6 Kg7 28.Qf4 Qe8 29.Qe5

29.Qc7+ has been suggested by several students, and appears to be as strong as Botvinnik's move in the game. 29...Kg8 30.Qe5 Kg7 31.Ba3.

Black to move

29...Qe7?

Botvinnik stated that this move was "inevitable" (156).

However, 29...h6 seems to be the best try. Burgess, et al. offer several detailed lines. I am presenting a fraction of these here with a few improvements made possible by stronger computers in the nearly twenty years since their book was published.

a) 30.Qc7+ Kg8 and the e-pawn needs protection, according to Burgess et al. Even so, Stockfish likes 31.Qd6 with a clear advantage for White.

b) 30.Ba3 Qd8 31.Qf4! is better than the suggestion in Burgess, et al. (31.Ne2) White seems to have the upper hand.

c) 30.Ne2 Na5 does not seem to lead to victory, as noted by Burgess, et al.

d) 30.h4 credited to Nunn in Burgess, et al. 30...Na5 31.Bc1! Qe7 32.Bg5

d1) 32...hxg5 is an important sideline that Burgess, et al. reject 33.hxg5 Nc6 34.gxf6+ Qxf6 35.Qxd5

After 35.Qxd5 (analysis diagram)
35...Ne7 seems to hold, according to Stockfish (Burgess, et al. have 35...Nd8)

d2) 32...Nc6 33.Bxf6+ Qxf6 34.Qxd5

After 34.Qxd5 (analysis diagram)
34...Nd8! (34...Qxh4 is suggested in Burgess, et al. It is the computer's third choice.) 35.Qd7+ Kf8 36.Qc8 and White seems to have a way to victory.

e) Stockfish likes 30.Qd6 30...Na5 31.Bc1 Nc6 32.Qc7+ Ne7 33.Qxa7+-.

Back to the game as played.

White to move

30.Ba3

The textbook deflection!

30...Qxa3

30...Qe8 31.Qc7+ Kg8 32.Be7 Kg7 33.Bd8+ Kf8 34.Bxf6+-.

31.Nh5+ gxh5 32.Qg5+ Kf8 33.Qxf6+ Kg8 34.e7 

34.Qf7+ also wins.

Black to move

For White's deflection to assure victory, he has to foresee this position and calculate to the point where Blaack runs out of checks.

34...Qc1+ 35.Kf2 Qc2+ 36.Kg3 Qd3+ 37.Kh4 Qe4+ 38.Kxh5 Qe2+ 39.Kh4 Qe4+

39...Qe1+ 40.g3 h5 41.Qg6+ Kh8 42.e8Q+

40.g4 Qe1+ 41.Kh5 1–0

Botvinnik won because his strategy was superior, and because he found the necessary tactics when they appeared on the board. This game is worthy of consideration as one of the best. Even so, Capablanca's surprising strategic errors in the late stages of the opening mar it somewhat.


*I suspect that whoever annotated this game for ChessBase MegaBase wrote these words, but I do not have MegaBase.

12 April 2017

Zwischenzug

Zwischenzug is also known as intermezzo. It is an in-between or intermediate move, often a check, thrown into the middle of a tactical sequence. Missing these can dramatically alter your calculation of variations.

It is the last entry in David Hooper, and Kenneth Whyld, The Oxford Companion to Chess (1992), where the authors define it as "a move interspersed during an exchange or series of exchanges" (460). They note that whether a given move is a zwischenzug may depend on one's point of view. It may be a natural part of the combination. Hooper and Whyld offer an interesting nuance in the definition, suggesting that the term is limited to failure of calculation.

Yasser Seirawan offers an instructive example in Winning Chess Tactics (2003), 118.

Black to move

Black intends to exchange rooks and then push the a-pawn. This plan fails because of an in-between check. After 1...Rxh4, White forces a draw with 2.Qd8+ Kh7 3.Qxh4+.

Two examples that I often use with my students are from Paul Morphy's first round games against James Thompson at the First American Chess Congress (1857).

White to move

In the first game, Thompson had planned a discovery as part of a series of exchanges on f5. 11.exf5 Bxf5 12.Nxf5 Rxf5 13.d4. However, Morphy interrupted the sequence with an in-between move.

11.exf5 d5! 12.Bb3 e4 13.dxe4 dxe4 and then Thompson missed the resource that could have kept him in the game, and so retreated the knight. Morphy won seven moves later.

In the second game against Thompson, Morphy used an intermezzo to win a pawn.

White to move

The Bishops will be exchanged, but White has some choice in the manner of exchange.

30.Bxb4 axb4 31.Rad7 and White (Morphy) went on to win an instructive endgame.

My young opponent at the Lou Domanski Chess Festival in Sandpoint, Idaho on Saturday found a slightly more sophisticated sequence involving an in-between move. It was not forcing, but offered me a series of unpleasant choices.

Black to move
After 16.e4
I played 16...dxe4, expecting 17.Nxe4 Nxe4 18.Bxe4 Rad8 with equality.

My opponent offered me the choice of a wrecked pawn structure on the queenside or on the kingside.

17.dxc5 Bxc5

I chose the wrecked kingside structure and the bishop pair.

18.Bxf6 gxf6 19.Nxe4 Be7 20.Qh5

I could have been only slightly worse after 20...Rad8, but instead blundered away my queen and resigned.