26 December 2009

Christmas @ Schemingmind.com

I don't normally comment on my games while they are in progress, but this is worth an exception. Note the King on c1.

Don't try to give me advice on the game (SP732: RBKNQNBR), because we are well past the position shown in the diagram. I played 4.d4.

20 December 2009

Extravagant Openings in Chess960 (cont.)

Continuing with Extravagant Openings in Chess960, the previous post established that the most popular first move of the CCRL engines for White in my random start position (SP201: QNRBBKNR) was 1.Nf3. Chosen in exactly 1/3 of the 24 sample games on file, it gives the position shown in the diagram.

Start Position 201 • 1.Nf3

The same sort of analysis I made for White, respecting various positional principles, can be made for Black. This gives the following options for non-extravagant moves:

  • Three of the four central Pawns can advance two squares (1...c5, 1...d5, & 1...f5), the e-Pawn being excluded for a tactical reason;

  • all central Pawns, plus the b-Pawn (to develop the Queen), can advance one square; or

  • the Knights can jump to their natural development squares (1...Nc6 & 1...Nf6).

The following table shows which moves were chosen by the CCRL engines.

12 x 1...Nf6
  5 x 1...c5
  2 x 1...d6
  2 x 1...f5
  1 x 1...d5
  1 x 1...e6
  1 x 1...h5

In exactly half of the games starting 1.Nf3, the move 1...Nf6 was selected, and five of the other six moves were predicted by the previous analysis. The only exception is 1...h5, which was chosen by the same engine that played 1.h4 successfully on the first move. After 1.Nf3 h5, the game continued 2.c4 h4 3.d4 c5 4.d5 d6 5.Nc3 h3 6.g3 Bd7, an extravagant follow-up to an extravagant first move! It eventually ended in a draw.

While I was working on this post, I started to wonder why the advance of a central Pawn one square on the first move is considered dubious for White, but acceptable for Black. This is certainly true for traditional chess (SP518: RNBQKBNR) and probably true for the position at hand, SP201. It's a question for which I don't have a good answer.

19 December 2009

Extravagant Openings in Chess960

Earlier this month on my main blog Chess for All Ages, I introduced the concept of Extravagant Openings in chess. The reason wasn't to invent yet another synonym for 'unorthodox chess openings', of which I gave a comprehensive list in that same post. It was rather to have a term I could use for dissecting chess960 openings. In the follow-up post What Makes an Opening Extravagant?, I defined extravagant openings as those where a player 'speculates on certain values at the expense of other values' and gave a couple of well known examples from traditional chess.

Taking the concept from chess to chess960 might be easier to discuss by way of an example. I used the dice-rolling method described in A Database of Chess960 Start Positions, and selected a random start position. It is shown in the following diagram (SP201: QNRBBKNR).

Start Position 201

I then looked at the first moves played by the CCRL chess960 engines (see the link in the sidebar and my previous post Chess960 Opening Theory) in this position. Since the CCRL insists on playing chess960 with 'Book learning: Off for all engines', the engines play openings according to how various positional principles -- the center, open lines, piece activity, etc. -- are weighted by the software. This guarantees variety throughout the games.

A glance at the diagram is enough to see that in SP201 the first moves conforming to positional principles are similar to the choices in traditional chess (SP518: RNBQKBNR):

  • One of the four central Pawns can advance two squares (1.c4, 1.d4, 1.e4, & 1.f4), or

  • the Knights can jump to the same natural development squares as in SP518 (1.Nc3 & 1.Nf3).
What did the CCRL engines play? The 72 games with start position QNRBBKNR saw seven different first moves:-

24 x 1.Nf3
16 x 1.d4
14 x 1.c4
  7 x 1.f4
  6 x 1.d3
  3 x 1.Nc3
  2 x 1.h4

Five of the six moves predicted above are in the list, most notably the first four. Only 1.e4 is missing. There might be a tactical reason for not choosing 1.e4 (attacks by ...g6, ...g5, or ...Nf6?), but I don't see anything that is not easily parried.

Also in the list are two moves not predicted above: 1.d3 and 1.h4. Both moves could therefore be classified as extravagant openings. The move 1.d3 has the same drawback as 1.d3 or 1.e3 in traditional chess; it fails to contest the center. The move 1.h4, one of the worst first moves in SP518, looks just as bad in SP201; it fails to do anything useful except liberate the Rook on a1, the same Rook that White needs to castle O-O.

Also worth noting is that the six games starting 1.d3 resulted in a +3-2=1 edge for White, while 1.h4 resulted in +1-0=1. Just as in life, extravagance in chess isn't necessarily a doomed cause. We would all be a lot poorer if it were.

13 December 2009

Practical Issues for Hosting Chess960

Chess960 @ Chess.com isn't just about playing (see What Are the Odds? for a post on my first games there). It's also about community. The main forum at Chess.com for the topic is Forums > Chess960 and Other Variants, which is more active than most forums on the subject.

A couple of threads on the forum caught my attention over the past few weeks. The first was Chess960 Tournaments: Variety. Although it addressed the strategy of running chess960 tournaments at Chess.com, the question applies to all such tournaments.

In chess960 tournaments, how often is the same starting position played? (A) The same starting position is used for all games of all rounds of the tournament; (B) The same starting position is used for all games of the same round of the tournament, but for every new round of the tournament, there is a new starting position; (C) [...]

It appears from comments to the thread that Chess.com uses strategy '(A)'. I also know from past investigations that the premier annual chess960 event, Chess Classic Mainz (see Chess960 @ Chess Classic Mainz), uses '(B)' for its chess960 open. Tournaments at Schemingmind.com (see Pyramids and Dropouts for background) use a strategy that the Chess.com author called '(D) There is a new starting position for every single game of the chess 960 tournament'. Which strategy is best?

The second thread was Subversion of the Spirit of Chess960, which addressed an issue that is more a problem for chess960 than for traditional chess.

Chess.com allows a player to cancel a game within a small number of moves. This seems like a reasonable policy for normal chess, but it has peculiar implications for chess960: Any player can start a bunch of games and selectively choose only those starting positions which match a given set of criteria.

Cancellation is particularly annoying in chess960 because, as I pointed out in Differences Between Chess and Chess960, the first few moves of chess960 require a lot more thought (i.e. work) than the first few moves of traditional chess. I've already had a few games where, just when I had played the first moves and was starting to appreciate the position, the game was abruptly cancelled. If this happens to players who are just starting chess960, it could deter them from continuing to play.

12 December 2009

What Are the Odds?

Since posting about Chess960 @ Chess.com, I've played a handful of correspondence games at the site ('online chess' they call it, as opposed to 'live chess'). By an unusual coincidence, my first two games started with the same position (SP638: RNKQRBBN) and I had White in both games.

A little thought convinced me that 1.e4 was a good first move. It opens diagonals for the Queen and light-squared Bishop, just as in traditional chess, with the added bonus that the e-Pawn is defended by the central Rook. My opponents must have used similar reasoning because they both played 1...e5, to which I answered 2.Nc3. That brought the games to the diagrammed position.

1.e4 e5 2.Nc3

In the first game, my opponent played 2...f6, activating the other Bishop, and I followed suit with 3.f3. Now, however, he (she?; Chess.com users are mainly anonymous) overplayed his (her?) position with 3...d5. This let me snatch the Bishop pair with 4.exd5 Bxd5 5.Nxd5 Qxd5, then menace the Queen with 6.Bd3. I thought I already the better game, but my opponent blundered a few moves later and resigned on the 16th move.

In the second game, my opponent followed my lead by playing 2...Nc6. This let me interfere with his normal development by playing 3.Bc4, when 3...f6 is not possible. He copied me again with 3...Bc5, but after 4.Ng3 g6, I forced his Bishop off the active diagonal with 5.Na4. He retreated with 5...Be7, then after 6.f3, tried to copy my plan with 6...Na5. Following the idea I used in the first game, I played a better retreat with 7.Bd3, leaving e2 for the Queen. Now after 7...f6 8.Qe2 Nf7, I was able to castle 9.O-O-O and again felt I had the better game.

06 December 2009

Four Cornered Bishops

In Attention to the Chess960 Center, I gave a position from the Nakamura - Aronian match, Chess960 World Championship, Mainz 2009, where the players paid attention to the center starting with the game's first moves (1.e4 e5). The positions in the diagram are from the second game of the same match.

Comparing the first diagram (SP451, BRNNKQRB) with the second, an inexperienced chess960 player might get the impression that the players have been moving their Pawns at random. There is, in fact, an instructive chunk of logic behind the moves leading to the second diagram.

One of the main features of this start position is that the four Bishops all start in the corners. Another feature is that all Bishops are protected by their respective Rooks.

The Bishops in the corners usually dictate a positional duel at the beginning of a game, since both players are forced to develop their Bishops on the long diagonals, where they come into contact immediately. The player who is the first to open a long diagonal can exchange Bishops as soon as the opponent opens the same diagonal. Balancing this, the decision to open either diagonal first leaves the opponent the opportunity to open the other diagonal first.

In the current game, White chose to open the a1-h8 diagonal with 1.b3. If Black plays 1...g6, White can exchange Bishops and Black will no longer be able to castle O-O. Black followed a similar strategy on the a8-h1 diagonal with 1...b5, but grabbed more space than White and left the possibility of ...Nc8-b6.

Now White continued the duel on the diagonals by playing 2.f3. This prepares a subsequent g2-g3 without allowing the exchange of Bishops on h1, thereby preserving the option to castle O-O. Black followed an identical strategy with 2...f6.

Now White made an overt play for space in the center with 3.d4, preparing Nc1-d3 and leading to the second diagram. He might not have noticed that his third move closed the a1-h8 diagonal, giving Black the chance to play the surprising 3...f5, advancing the f-Pawn for the second consecutive move. Consequently, Black's dark squared Bishop will have more freedom on its long diagonal than White's light squared Bishop will have.

After three moves each, the contours of the subsequent struggle have been defined and the game is launched. The PGN for the full game, courtesy Chesstigers.de, is:

[Event "CCM9 - Chess960 Rapid WCh"]
[Site "Mainz"]
[Date "2009.07.30"]
[Round "8.1"]
[White "Aronian, Levon"]
[Black "Nakamura, Hikaru"]
[Result "0-1"]
[WhiteElo "2800"]
[BlackElo "2777"]
[Variant "chess 960"]
[SetUp "1"]
[FEN "brnnkqrb/pppppppp/8/8/8/8/PPPPPPPP/BRNNKQRB w GBgb - 0 1"]
[Source "Chess Tigers"]

1.b3 b5 2.f3 f6 3.d4 f5 4.Nd3 g6 5.Qf2 Bf6 6.g3 Qh6 7.e3 Ne6 8.Qe2 Nb6 9.Nc3 a6 10.Nc5 Nxc5 11.dxc5 Qg7 12.Qd3 b4 13.cxb6 cxb6 14.Nd5 Bxa1 15. Nc7+ Kf7 16.O-O Bc3 17.f4 Bxh1 18.Kxh1 Qf6 19.Rbd1 Qc6+ 20.Qd5+ Qxd5+ 21. Rxd5 Rb7 22.Nxa6 Ra8 23.Nxb4 Bxb4 24.a4 Bc5 25.Re1 e6 26.Rd3 d5 0-1

Nakamura appears to have outplayed Aronian already in the opening.

05 December 2009

Attention to the Chess960 Center

In More from Mainz 2009 I quoted GM Grischuk saying,
The first year [at Mainz] I was playing like g4/b4, but in order to play like this successfully you have to be either Aronian or Nakamura. They look to be the only two persons who do it successfully. Kamsky does it but he tries more like f4/c4, but they are g4/b4. It works for them, but for me it was just terrible. Since then I try to play a more central approach at the starting stage.

After playing chess960 for almost a year and a half, I have some idea what Grischuk is saying. There are two distinct, fundamental ways to treat a chess960 opening. The first way is to follow traditional chess opening principles, of which one of the most important is to pay attention to the center. The second way is to pay less attention to the center, but by taking into account the specific start position, to emphasize the rapid development of the pieces to good squares, even if this means making early moves like g4 or b4.

Grischuk didn't pick the names Aronian and Nakamura at random; they have been among the most successful competitors at recent Mainz events. Aronian won the main chess960 event at Mainz on several occasions (see Chess960 @ Chess Classic Mainz for a list of his accomplishments), although he finished second to Nakamura in the most recent tournament (see CCM9: Nakamura, Grischuk, and Rybka).

This year the two 2700 GMs played two games in the preliminary stage of the closed Rapid World Championship and then met in the final stage. Nakamura lost to Aronian +0-1=1 in the preliminaries, but won +3-0=1 in the finals.

Most of the six games between the two players were more like the g4/b4 variety, but one game used more classical principles in the attention paid to the center. The following diagram shows a position from game three of the final match.

Chess960 World Championship, Mainz 2009
Aronian, L.

Nakamura, H.
(After 8...Bh6-g7)

At first glance the position might be mistaken for the Philidor Defense (1.e4 e5 2.Nf3 d6) in traditional chess, but the Queens in the corners, the Kings on the c-file, and the position of the Rooks, especially the Rook on d3, are a dead giveaway that the position is chess960 (SP666, RNKRBBNQ). White continued 9.Be3, defending the attacked d-Pawn a third time and letting the Rook on d3 retreat if necessary. The PGN for the full game, courtesy Chesstigers.de, is:

[Event "CCM9 - Chess960 Rapid WCh"]
[Site "Mainz"]
[Date "2009.07.30"]
[Round "9.1"]
[White "Nakamura, Hikaru"]
[Black "Aronian, Levon"]
[Result "1-0"]
[WhiteElo "2777"]
[BlackElo "2800"]
[Variant "chess 960"]
[SetUp "1"]
[FEN "rnkrbbnq/pppppppp/8/8/8/8/PPPPPPPP/RNKRBBNQ w DAda - 0 1"]
[Source "Chess Tigers"]

1.e4 e5 2.Nf3 g6 3.Nc3 c6 4.g3 d6 5.d4 Bd7 6.Rd3 Na6 7.a3 Bh6+ 8.Bd2 Bg7 9.Be3 exd4 10.Bxd4 Nc5 11.Rd2 Nf6 12.Ng5 Rf8 13.O-O-O O-O-O 14.e5 Ng4 15.f4 Ne6 16.Nxe6 Bxe6 17.h3 dxe5 18.Bxa7 Nf6 19.Ba6 e4 20.Qg1 Rxd2 21. Bxb7+ Kxb7 22.Qb6+ 1-0

The ratings (WhiteElo and BlackElo) are special chess960 ratings calculated by Chess Tigers. In my next post, I'll show a position from another game between the two players where less attention was given to the center.

29 November 2009

Learn to Castle Correctly (Mechanics)

It's the sixth and last round of a SchemingMind.com chess960 dropout tournament (see Pyramids and Dropouts for more about these events) held a few years ago. The starting field of 85 players has been whittled down to 10. These are the survivors, the crème de la crème at Scheming Mind, battling for the annual chess960 championship at one of their favorite online play sites.

After a few days play, a game starting NQRBBKNR (SP217) and continuing 1.Nf3 c5 2.c4 Nb6 3. b3 Nf6 4. e4 O-O reaches the following position


(After 4...O-O)

Now White timidly asks Black, 'Can you tell me, please, how can I castle? It's enough to move the king to g1 or there's something else I should do?'. Black's first reaction must have been, 'What the...? How did this guy survive the first five rounds, two games per round, without knowing the rules of castling?' The second reaction might have been, 'Now I get it! He doesn't know how to execute the castling move on Scheming Mind', followed by the same refrain, 'How did this guy survive the first five rounds without knowing the mechanics of castling?'

I looked at White's previous games in the tournament and verified that he had never castled. Game after game, with the King stuck in the center and a Rook out of play, White must have been an exceptionally good defensive player to have faced increasingly skilled competition without ever castling.

When castling in traditional chess, most software works the same way. You click on the King, then click the square located two squares toward the castling Rook. The software understands your intention exactly and moves both the King and the Rook to their castled squares.

In chess960, the castling intention is not so straightforward. Sometimes both pieces move, sometimes only the King moves, and sometimes, most illogically for traditional chess players, only the Rook moves. How to tell the software that, for example, clicking on the Rook this time means castling, but next time means a normal Rook move? There is no standard way to do this and the mechanism for castling depends on the software being used.

Before you play chess960 using new software or on a new site, make sure you know how to execute a castling move. Take the time (for once?) to read the instructions. Later in your games, it will save you much defensive maneuvering and perhaps a little embarrassment.

28 November 2009

Learn to Castle Correctly (Rules)

Here's a war story from the fourth game of a match between two super grandmasters at Mainz 2004 -- Gerling Match : Chess960 World Championship : Svidler vs Aronian. A problem occurred in the following position.

Chess960 World Championship, Mainz 2004
Aronian, L.

Svidler, P.
(After 32.e5-e6)

The story as told on the Chesstigers.de page involved an error in castling O-O-O.

This position caused quite a stir in the fourth game of the Gerling Match between Levon Aronian and Peter Svidler. Levon Aronian took his rook on a8, jumped over the King and put it on d8. However, he forgot to take his King which had to be placed on c8 to fulfill all the requirements for a-side castling in Chess960. If he would have done that, the game would be over: Qa8 check and mate!

Peter Svidler stopped the clock and arbiter Sven Noppes came to see what was going on. Castling was possible, the mistake Aronian made was that he took his rook first, so he had to castle a-side.

Peter Svidler showed that he is a gentleman on the board and allowed Aronian to correct his move. The Armenian had to play Ra7 and kept the better position. However, after this faux-pas Aronian completely lost control and finally lost the game.

Was this just a mistake by the young Armenian, or did he try to win with a dirty trick? Aronian joked during the press conference : "Off course I wanted to cheat, just like in his game against The Baron in the computer match." Peter Svidler said: "I do not have a problem with Aronians mistake, and when you have only 40 seconds on the clock, like in this case, it is possible that you mix up the castling rules".

The complete PGN game score (SP725, RKBBNQNR), again courtesy Chesstigers.de, is:

[Event "CCM4 - Gerling Match (Chess960 WCh)"]
[Site "Mainz"]
[Date "2004/8/6"]
[Round "4"]
[White "Svidler"]
[Black "Aronian"]
[Result "1-0"]
[FEN "rkbbnqnr/pppppppp/8/8/8/8/PPPPPPPP/RKBBNQNR w HAha - 0 1"]
[Input "DGT1805"]

1.e4 e5 2.f4 exf4 3.Qxf4 Ne7 4.Ngf3 d6 5.d4 f5 6.e5 Nd5 7.Qd2 Nb6 8.Nd3 dxe5 9.dxe5 g6 10.a4 a5 11.b3 Ng7 12.Be2 Ne6 13.Bb2 Nd5 14.O-O h5 15.Nf2 Nb4 16.Bc4 Qh6 17.Qc3 Be7 18.Rad1 Nc6 19.Nd3 h4 20.Bb5 Ncd8 21.Nf2 g5 22. Bc1 Qg7 23.Nd4 Bb4 24.Nxe6 Nxe6 25.Qf3 Bc5 26.Kh1 h3 27.gxh3 Nd4 28.Qd5 b6 29.Rxd4 Bb7 30.Bc6 Bxc6 31.Qxc6 Bxd4 32.e6 Ra7 33.Ba3 Qe5 34.e7 Bc5 35.Nd3 Qxe7 36.Nxc5 bxc5 37.Bxc5 Qe5 38.Qb5+ Ka8 39.Bxa7 Qxb5 40.axb5 Kxa7 41.Rxf5 Rxh3 42.Rxg5 Kb6 43.Rg3 Rh4 44.Rc3 Rh5 45.Rc6+ Kb7 46.Rc4 Rxb5 47.h4 Re5 48.Kg2 c5 49.Kf3 Kc6 50.Kg4 Re2 51.h5 a4 52.bxa4 Kd5 53. Rc3 Kd4 54.Rh3 Rxc2 55.h6 Rg2+ 56.Kf5 Rg8 57.h7 1-0

Not all opponents would be as forgiving as GM Svidler. Learn how to castle correctly in chess960. It's not that difficult!

22 November 2009

Grischuk - Mamedyarov, Mainz 2009

In More from Mainz 2009, I gave a partial transcript from an interview -- Grischuk post-FiNet win -- on Chessclub.com, and promised to feature a game from winner Grischuk in a future post. During the interview Grischuk mentioned his game against Mamedyarov, so it looks like a good choice.

The start position (SP535, RNBKQNRB) is not too far from a traditional chess game. The royalty is in the center and the Queenside pieces ('a-side' for the purists) are in their traditional places ('RNB'). Only the Kingside pieces ('h-side') are scrambled. The first four moves were 1.g3 g6 2.c4 e5 3.Nc3 Ne6 4.d3 c6, bringing the game to the following position.

8th FiNet Open, Mainz 2009
Mamedyarov, S.

Grischuk, A.
(After 4...c7-c6)

Here is an explanation, as I see it, of those first moves.

  • 1.g3: Opens the diagonal for the Bh1. The move 1.g4 is an alternative, but as Grischuk explained in the interview, he's wary of the b4/g4 ideas.
  • 1...g6: The same thinking as for 1.g3, from Black's point of view.
  • 2.c4: Prepares the development Nb1-c3 and takes control of d5, an important central square. The move is reminiscent of the English opening in traditional chess.
  • 2...e5: Prepares the development ...Nf8-e6 and takes control of d4, also an important central square. The move is reminiscent of an important counter to the English opening in traditional chess (1.c4 e5).
  • 3.Nc3: Follows through the previous move and develops the Knight to its best square.
  • 3...Ne6: Ditto.
  • 4.d3: Prepares the development of the Bc1 on its long diagonal.
  • 4...c6: Counters the influence of the White Bishop on the long diagonal and prevents a White piece from moving to d5.

So far, both players have developed their pieces in classic style by developing a Knight to a good square, opening a diagonal for a Bishop, and paying attention to the center. Now White probably considered what to do about further development. The move 5.Ne3 forces the Bishop on c1 to go eventually to d2, where it blocks the Queen from developing. The move 5.Be3 forces the Knight on f1 to go to d2, where it also blocks the Queen.

This thinking leads to the idea 5.Bh6, where White has to calculate the tactical consequences of the Bishop trap 5...g5. After these fifth moves for both players, the game continued 6.h4 gxh4 7.Be4 Bf6 8.Ne3 hxg3 9.O-O-O. White is temporarily two Pawns down, but Black is lagging badly in development on the Queenside.

Since this is a chess960 blog, and the only real difference between traditional chess and chess960 is the opening phase, I'll stop here. White has castled O-O-O, while the Black King will find shelter on c7. Here is the complete game score...

[Event "CCM9 - 8.FiNet Open"]
[Site "Mainz"]
[Date "2009.07.31"]
[Round "8.1"]
[White "Grischuk, Alexander"]
[Black "Mamedyarov, Shakhriyar"]
[Result "1-0"]
[Variant "chess 960"]
[SetUp "1"]
[FEN "rnbkqnrb/pppppppp/8/8/8/8/PPPPPPPP/RNBKQNRB w GAga - 0 1"]
[PlyCount "97"]
[EventDate "2009.??.??"]
[EventCountry "GER"]
[Source "Chess Tigers"]
[SourceDate "2009.01.01"]

1.g3 g6 2.c4 e5 3.Nc3 Ne6 4.d3 c6 5.Bh6 g5 6.h4 gxh4 7.Be4 Bf6 8.Ne3 hxg3 9.O-O-O d6 10.fxg3 Bg5 11.Rh1 Bxh6 12.Rxh6 Qf8 13.Nf5 Na6 14.Qf2 Bd7 15.Rdh1 Nac5 16.b4 Na6 17.a3 Kc7 18.Kb2 Rd8 19.Qxa7 Rb8 20.Rxh7 Ng5 21. R7h5 Bxf5 22.Bxf5 Ra8 23.Qe3 Qe7 24.Rc1 Kb8 25.g4 Nc7 26.d4 f6 27.d5 c5 28.b5 Ne8 29.Rh2 Qc7 30.Ne4 Nxe4 31.Qxe4 Qa5 32.Qe3 Ka7 33.Qc3 Qd8 34. Rch1 Ng7 35.Bc2 Ne8 36.Qf3 Qa5 37.Rh7 Kb6 38.R1h4 f5 39.Rf7 fxg4 40.Qg3 Qd2 41.Rhh7 Ra7 42.Qh4 Qd4+ 43.Kb1 Qg1+ 44.Ka2 Nc7 45.Qe7 Nxb5 46.Qxb7+ Rxb7 47.Rxb7+ Ka5 48.Rxb5+ Ka6 49.Rhb7 1-0

...courtesy of Chesstigers.de. For an explanation of the PGN specific to chess960, see my previous post Chess960 PGN.

21 November 2009

Who Is the 'Father of Chess960'?

In The First Recorded Fischerandom Game?, I noted that the 2009 edition of 'The Sorcerer's Apprentice' by Bronstein & Fürstenberg mentions that 'Fischer Random is a derivative of an idea that Bronstein himself has invented twenty years earlier'. That quote is from a Google translation of a Dutch review of the book and not a quote from the book itself. Whatever the book says will remain a mystery to me until I get my hands on a copy. In the meantime, I can still explore the idea of who is responsible for the invention of Fischer Random, better known on this blog as chess960. The title 'Father of Chess960' hangs on the outcome of the research.

The ChessVariants.com page on Fischer Random Chess says,

Fischer Random Chess is somewhat similar to the older Shuffle Chess, or Prechess (or other related variants), yet has a unique style of its own. An extensive introduction and history of the game was written by Eric van Reem.

The van Reem article, The birth of Fischer Random Chess, is available on multiple web sites. It dates the 'birth' to Buenos Aires 1996, the event that I covered in Fischer Announces Fischerandom. Gligoric, in his ground-breaking 'Shall We Play Fischerandom Chess?', gave a more detailed account. After mentioning Capablanca's erstwhile efforts to improve the game that he felt was under threat from draws, Gligoric wrote,

Fischer's concentration on this problem went much deeper. During his stay in Saint Stefan [better known outside Serbia as Sveti Stefan] in 1992, he recommended shuffling all the pieces at random on the back row before the beginning of each game. [...]

It turned out that Fischer's first plan would make 2400 different commencing positions. Immediately after his sensational return to the chess scene in 1992, he began experimenting privately with this kind of chess against colleagues and chance visitors. Although Fischer was pleased that the mathematical sum of starting positions was very large, he soon discovered that eventually having two Bishops of the same color made an unpleasant impression, producing one-sided and limited opportunities on the chessboard. It was also clear that obstructing the right to castle would mean a step backward toward the primitive distant chess past and if the intermingling of pieces on the back row made castling impossible for both sides, this would inflict irreparable damage on playing strategy as well.

The result of Fischer's constant meditation on how to give alternative life to the game of chess, threatened by the exhaustion of its creative resources, was the formulation, in September 1993, of the rules of "Fischerandom Chess" which are quoted in a separate chapter of this book. [p.36]

I covered those rules in Fischer's Rules of Fischerandom.

Prechess, mentioned above in the ChessVariants.com quote, is a variant of shuffle chess where the players take turns placing single pieces on the back rank. Since the rules don't appear to have been formalized anywhere, restrictions on the Bishops and possibilities for castling depend on who is playing and what was agreed beforehand.

Who is the 'Father of Chess960'? There are three key requirements: (1) shuffle chess with the White and Black pieces starting opposite each other; (2) the two Bishops for each side on different colored squares; and (3) castling into the familiar O-O and O-O-O positions. Other would-be inventors might have proposed (1) and (2), but Fischer proposed (3). That last contribution, which steers the game from a shuffled variant into positions fully reminiscent of traditional chess, gives Fischer the title.

15 November 2009

A Chess960 Catastrophe

Talk about opening disasters! The diagram shows the position after three moves each in a game between two 2700+ players from Mainz 2005. White played 4.Nc5, threatening the royal fork on d7 (plus the small matter of a smothered mate). However Black responds, White has 5.Qb5, reinforcing the fork and adding mate on b7 to Black's woes.

4th FiNet Chess960 Open (2005 Mainz)
Bacrot, Etienne

Aronian, Levon
(After 3...Bd8-f6)

The start position was RKRBNQBN (SP941) and the initial moves were 1.e4 e5 2.Nd3 Ng6 3.f4 Bf6. Black's last move led directly to disaster, but the preceding moves 1...e5 and 2...Ng6 were probably not the best either. After 1.e4, the CCRL engines (see the 'Resources' link in the sidebar) prefer 1...f5 and 1...Ng6. Is the position after 1...e5 definitely lost? Perhaps the losing move was 2...Ng6; more analysis required.

14 November 2009

Setting up a Chess960 Position

In my previous post, The First Recorded Fischerandom Game?, I wrote, 'For reasons that I'll give some other time, the order by value is my preferred method of setting up a chess960 start position.' By that somewhat cryptic statement, I meant that I use a little procedure -- an algorithm -- to set up the pieces at the start of a chess960 game. That procedure involves placing the pieces in descending order of value.

Setting up the pieces to start a traditional chess game (RNBQKBNR) doesn't take any special effort. Experienced players do this so often that the pieces seem to find their correct start positions without any conscious effort by the players. The fingers grab a few pieces and scatter them on the correct squares the way a coin sorter sorts a bag of random coins; they just drop into the right slots. Sometimes a Bishop and Knight, or a King and Queen, might be switched accidentally, but this is usually spotted before the first move is made.

Setting up a new chess960 position is not so automatic. The pieces are almost always placed according to instructions that differ at the start of each game. It takes a conscious effort to place each piece on the correct square, and even then, there is always a chance that the pieces might not have been placed correctly.

A long time ago I discovered a method of placing pieces on a chess board when setting up a position other than the traditional start position. This is required, for example, when working from a diagram in a book or magazine. It turns out that the same basic method works for chess 960. I described the general procedure for traditional chess in an article I wrote for About.com: Improve Your Middle Game (Part 1 - Patterns).

Here's another trick I use frequently. It's a procedure for setting up a position on a board. First, clear the board. Don't try to set up a position by adjusting the pieces already in place unless the old position is almost identical to the new. Second, place the two Kings on the board. Third, set up the Pawns. Then add the Queens (both White and Black) if they are present, then all the Rooks (White and Black), and finally all of the minor pieces (ditto).

'What's the big deal?', I hear you asking. 'What difference does that make?' Perhaps no difference whatsoever, except that it works for me.

Setting up the Kings first tells me immediately where the most important pieces on the board are located. Are they on their original squares, on the same side, on opposite sides, or in an unusual place?

Setting up the Pawns without the other pieces gives me a quick picture of the Pawn structure. Does one side have a numerical advantage? Are there any classic weaknesses like doubled or isolated Pawns? How many islands are there? Since the Pawn structure changes very slowly, it's often the key to devising a long term plan. This is one of the things Philidor meant when he said, 'The Pawn is the soul of chess.'

Setting up the Queens, then the Rooks, then the minor pieces gives me another quick count on the material. Is there an advantage? An imbalance? How do the minor pieces match? Does one side have two Bishops and a Knight where the other side has two Knights and a Bishop?

By the time I've set up the position, I've already registered a lot of information about what's happening on the board. This makes up for the lack of information from not having played the game from the starting moves.

That same procedure, with a couple of tweaks, also works well for a chess960 start position. The first tweak is that the board doesn't have to be cleared completely. Moving the pieces to the center of the board (or off the board) is even more efficient. The second tweak is that the Pawns don't have to be cleared; they can be placed immediately on the second and seventh ranks, just like when starting a traditional chess game.

After that, however, the pieces are placed in order of their value: first Kings, then Queens, then Rooks, then minor pieces. The advantages to this procedure are:

  • Placing the Kings first helps to see that the most important piece is not placed in the corner, where it is never allowed to start the game.
  • Placing the Queens early allows to see where the most powerful piece on the board is located.
  • Placing the Rooks early provides a quick visual check that the King has been placed between the two Rooks. As a bonus, the castling choices are more obvious when there are no minor pieces on the board.
  • Placing the Bishops at the same time provides another visual check that they are starting on opposite colored squares.

And that's it. On top of these visual checks for the individual pieces, placing the pieces of the same value at the same time for both colors helps to ensure that the right pieces start opposite each other.

I've also discovered that this procedure makes it easier to set up the pieces when I'm sitting on the Black side of the board. I just take my instructions, QRKNBBNR for example, turn them upside down (RNBBNKRQ), and place the pieces using the same method I just described. It's not flawless, but it works much better than placing the pieces randomly.

08 November 2009

The First Recorded Fischerandom Game?

Between Fischer's announcement of his variant -- TWIC 88 (24 June 1996), Fischer Announces Fischerandom -- and the collapse of his kickoff match -- TWIC 91 (14 July 1996), Fischerandom's Inauspicious Start -- TWIC carried another item on Fischerandom.
13) Fischerandom chess game between Bronstein and Douven. Tom Furstenberg reports: IGM David Bronstein - IM Rudi Douven. This game was played on the 1st board during a friendly match on 30 boards between Chess Club Anderlecht of Belgium vs. Eindhovense Schaakclub of The Netherlands on 30.06.96. The time limit used was 1 hour 45 minutes for the first 40 moves, thereafter 15 minutes for the rest of the game.

The initial position for this game of Fischerandom Chess was White: Kd1, Qa1, Rb1, Rg1, Be1, Bh1, Nc1, Nf1. Black: Kd8, Qa8, Rb8, Rg8, Be8, Bh8, Nc8, Nf8

1.d4 d5 2.Nd3 Nd6 3.g3 e6 4.Bb4 a5 5.Bxd6 cxd6 6.a4 Qa6 7.Nd2 Nd7 8.b3 Nf6 9.c4 Bd7 10.e3 0-0 (The black King goes to g8 and the black Rook to f8) 11.Ke2 g6 12.Rgc1 Rfe8 13.Qa3 e5 14.dxe5 dxe5 15.b4 e4 16.Nc5 Bg4+ 17.Ke1 Qd6 18.cxd5 Qxd5 19.bxa5 Qh5 20.h4 Bf5 21.Nxb7 Qg4 22.Bg2 Nh5 23.Nf1 Be6 24.a6 Be5 25.Nh2 Qf5 26.Nd6 Bxd6 27.Qxd6 Qa5+ 28.Kf1 Rxb1 29.Rxb1 Rd8 30.Rb8 Bc8 31.Rxc8 Rxc8 32.Bxe4 Qxa4 33.Bb7 Rc2 34.Qb8+ Kg7 35.a7 Nxg3+ 36.Kg2 Nf5 37.a8Q Nxe3+ 38.Kf3 Rxf2+ 39.Kxf2 Nd1+ 40.Kg3 Qb3+ 41.Bf3 Black Resigns. [TWIC 90, 7 July 1996]

This was followed by the game in PGN format, where Crowther commented, 'Of course I've had to split the game in two because of the castling.' Of course! Even today, 13 years later, there is much chess software that doesn't understand chess960.

When I read Crowther's report, my first reaction to the initial position was 'That can't be right!', because the King was not placed between the two Rooks. Then I realized that Crowther had listed the pieces in order of value (KQRRBBNN), rather than in order of board position (QRNKBNRB). For reasons that I'll give some other time, the order by value is my preferred method of setting up a chess960 start position.

The start position QRNKBNRB is no.491 (SP491). After White's 10th move, the players reached the following position.


(After 10.e2-e3)

Now Black castled 10...O-O (Crowther: 'The black King goes to g8 and the black Rook to f8') and White played 11.Ke2. Here the game starts to look very much like a traditional chess game, except for the Black Bishop buried on h8. After 11...g6, even that difference fades into the game score.

Given the general lack of material about chess960, it's not surprising that there is very little on the web about the Bronstein - Douven game. Google locates David Bronstein herzien?, a Dutch review of a new (2009) edition of 'The Sorcerer's Apprentice' by Bronstein & Fürstenberg. That's the same Furstenberg who reported the game to TWIC in 1996.

Google also does a reasonable job of translating the book review, where we learn the reviewer's main objective: 'The question was whether the need is so new and expanded version. And to answer that question, go look for the differences.' That's a good question, because I have the 1995 edition of 'The Sorcerer's Apprentice', and I would also like to know what's new. It turns out that the chess960 portion of the review is:

And gives a lot Fürstenberg Bronstein - Douven, from a friendly game Anderlecht - Eindhoven, with random chess is played. The reader is warned of passing and the fact that Fischer Random is a derivative of an idea that Bronstein himself has invented twenty years earlier.

Perhaps not coincidentally, near the end of the 1995 edition is a brief Q&A passage explaining why Bronstein, a World Championship challenger in 1951, might have been attracted to chess960 in 1996:

Q: Classical chess appears to be in a state of crisis. • A: Because chess has already been studied so thoroughly. The aura of mystery has vanished! Today chess relies on the splendid memory of the young. They complain that they have to work hard, that our generation does not understand them, does not realize how difficult it is to digest thousands of games, commit a mass of information to memory, and not confuse the proper order of moves in reproducing a 20-move long variation on the board. I appreciate that this involves enormous physical and mental strain. But this has nothing in common with the chess that was played by my generation. (1995, p.289)

What about the statement that 'Fischer Random is a derivative of an idea that Bronstein himself has invented twenty years earlier'? That would also make a good subject for another post.

07 November 2009

Fischerandom's Inauspicious Start

The press release issued for Fischer's press conference in June 1996 -- see Fischer Announces Fischerandom for the full text of the announcement -- contained two mentions of a forthcoming match.
The object of the conference was to publicize the launch of Fischer's new game, Fischerandom Chess, and to announce the match of Fischerandom Chess between Philippine Grandmaster Eugene Torre and two-time Argentine champion International Master Pablo Ricardi which begins July 12.


Now the world awaits the first Fischerandom Chess match which will commence at Pasaje Dardo Rocha in the Argentine city of La Plata on July 12. The match between Torre and Ricardi will be played until one player accumulates four victories, draws not counting.

What was the result of that match? The only mention I could find was in TWIC 91 (14 July 1996).

8) Fischerrandom Match between Torre and Ricardi. Eric van der Schilden is there for the match and will cover it on the TASC www page. It has been postponed for a few days due to the continuing illness of Ricardi see: http://www.tasc.nl/frandom

The tasc.nl link is long defunct, but the page lives on in Archive.org: web.archive.org/web/*/www.tasc.nl/frandom/. Here's a screen shot of that page, titled 'FischeRandom Match : Torre-Ricardi'.

After informing us that

On July 11 the final press conference saw the presentation of the clock and shuffler, two electronic devices essential for the new chess: [Fischer's clock and shuffler]. From July 12 onward, Eugenio Torre and Pablo Ricardi should have played the first ever FischeRandom-event: [Rules for the Torre-Ricardi match].

the page ends abruptly with (sic)

Torre-Ricardi match cancelled. Finally the true reason of the delays in starting with the Torre-Ricardi match has surfaced. It appears that the Argentinean organisers couln't show their part of the prize fund upon arrival of the players as was stipulated in their contracts. Thereupon Fischer, who was to donate the other part of the prize money, refused to let the match start. Last-minute attempts to solve this impasse remained invain. The money could not be provided. Fischer set an ultimatum to the morning of July 17. Nothing happened and he and Torre packed their bags and left La Plata that same day.

Over three weeks passed between Fischer's press conference and the cancellation of the kickoff match.

01 November 2009

Fischer's Rules of Fischerandom

When I wrote the post Fischer Announces Fischerandom, I omitted the rules published by Fischer in June 1996. They can be found here...
Bobby Fischer's Rules of Fischerandom Chess

...For a much simpler version of the rules, see Fischer Explains the Rules of Fischer Random. The rules were also copied into Gligoric's Shall We Play Fischerandom Chess?, in the chapter titled 'Fischerandom Rules' (p.86-92). For other copies of the rules, which likely lead to other resources about chess960, see Google: "pieces on their respective back rows receive an identical random shuffle".

Fischer's rules included the following explanation...

White and Black have identical positions. From behind their respective Pawns the opponents' pieces are facing each other directly, symmetrically. Thus for example, if the shuffler places White's back row pieces in the following position: Ra1, Bb1, Kc1, Nd1, Be1, Nf1, Rg1, Qh1, it will place Black's back row Pieces in the following position, Ra8, Bb8, Kc8, Nd8, Be8, Nf8, Rg8, Qh8, etc.

...where the position used in the example is shown in the following diagram.

Start Position 760

Did the position have some special meaning for Fischer or was it also chosen at random?


Later: Gligoric mentions earlier in his book (p.36) that the rules he quotes were formulated in September 1993, almost three years before the press conference announcing them.

31 October 2009

Fischer Announces Fischerandom

Fischer's initial press release about *his* version of chess was an item in Mark Crowther's THE WEEK IN CHESS (TWIC) no.88, dated 24 June 1996. Here's a copy of the press release:

Bobby Fischer returned to Buenos Aires, Argentina after 25 years and it was as if he had never left. At a press conference on June 19 in the Argentine capital, the World Chess Champion was received by hundreds of journalists and chess fans, many of whom had come from all over the world. It was apparent from the feeling of anticipation in the room before he arrived that the Fischer mystique is alive and well.

The object of the conference was to publicize the launch of Fischer's new game, Fischerandom Chess, and to announce the match of Fischerandom Chess between Philippine Grandmaster Eugene Torre and two-time Argentine champion International Master Pablo Ricardi which begins July 12. Both players attended the conference and displayed enthusiasm regarding the match and the new game.

Before taking questions from the assembled press, Fischer spoke out on several topics. He apologized for bringing up subjects unrelated to Fischerandom Chess, and he then began a counterattack on several companies that he claimed had been defrauding him of huge amounts of money as well as trying to destroy his image. He targeted the British publisher Batsford for releasing a forged and unauthorized new edition of his renowned chess classic "My 60 Memorable Games", for deliberately making erroneous changes in the text itself and for never having paid him royalties for the book. He also attacked the motion picture company Paramount, producer of the hit film "Searching for Bobby Fischer", saying he never received "a penny" from the film. He also mentioned a CD-ROM, "Bobby Fischer Teaches Chess", that had been made using his name unlawfully. He strongly criticized US Secretary of Commerce Mickey Kantor for not protecting his intellectual property rights in direct contradiction with Kantor's position on Red China, which Kantor has denounced for alleged violations of international copyrights. Fischer angrily accused the U.S. government of a double standard and disgusting hypocrisy in this regard. He made the point that his new, improved version of classical chess will eliminate the large amount of study and analysis that are involved in chess. He stated that many games are prearranged before the players begin the game, and that even the so-called world championship matches between Russian players Kasparov and Karpov had been prearranged, and that this would be impossible in Fischerandom Chess.

Fischer also ridiculed the U.S. government for indicting him and issuing a federal arrest warrant in his name for his alleged violation of an executive order by then President Bush barring U.S. citizens from doing business with Yugoslavia. Fischer claimed one of the reasons the U.S. government has indicted him and issued the arrest warrant, which is valid all over the USA, was to prevent him from returning to the USA to get access to his enormous file on the first so-called world championship match between Karpov and Kasparov so that he could write a book proving that that match was prearranged move by move.

After making these impassioned remarks, Fischer answered questions from the press for nearly an hour. In explaining the concepts behind Fischerandom Chess, Fischer said that although the rules are basically the same as those of traditional chess, each game begins from a different starting position, randomly chosen by the Fischerandom Chess Computerized Shuffler, making creativity and chess talent more important than analysis and memorization. He also pointed out that due to such long hours in front of the computer screen and with books, many top young players today, such as Kamsky, Kramnik and Anand, wear thick glasses. He also mentioned that all of the study necessary to play conventional chess made it into hard work, and that he had got into chess in order to avoid work!

With many people wondering about the future of chess after the IBM computer Big Blue beat Garry Kasparov earlier this year, Fischer's statement that computers would be at a considerable disadvantage in Fischerandom Chess received a great deal of attention. He stated that without access to databases of the millions of opening variations in traditional chess, computers do not really play chess all that well.

Now the world awaits the first Fischerandom Chess match which will commence at Pasaje Dardo Rocha in the Argentine city of La Plata on July 12. The match between Torre and Ricardi will be played until one player accumulates four victories, draws not counting.

The appearance of Robert J. Fischer in Buenos Aires left no one disappointed. After finishing with the questions, Bobby signed autographs for the dozens of fans who had come to catch a glimpse of the legendary genius. Many of the chess fans had clear memories of his last visits to Buenos Aires in the early seventies. Fischer's popularity here was clearly shown as well by the intense coverage by all the local media. Everyone is eagerly looking forward to Bobby Fischer's next move, whether it be on or off the board.



I've truncated the press release to remove the rules, which were longer than the release itself. Since they represent an integral contribution to the history of chess960, I'll post them elsewhere. Crowther had this to say about Fischer's press conference (copied verbatim):


Bobby Fischer returned to the limelight three years after his match against Boris Spassky in Yugoslavia. Bobby Fischer provokes extreme reactions from most chess fans. I'm very much of the school that found both his play and his life-story fascinating (Bobby Fischer Profile of a Prodigy by Frank Brady is an excellent and very balanced account of his career up to 1972) and find it rather sad he won't return to over-the-board chess. (Brady quote "He [Fischer] accepted an invitation to compete in the great Capablanca Memorial Tournament to be held in Havana, Cuba from August 25th to September 26th. I know some people who cried with joy when they heard the news.") This would certainly be my reaction if he decided to play now. But the press conference and the wait from 1992 suggests that Fischer doesn't have the commitment to work on chess anymore, this press conference is Fischer effectively announcing his retirement.

Whilst I'm sure that he has thought very deeply about the development of the Fischerandom Chess I don't think that things have changed so radically in over-the-board chess as he makes out. Fischer himself brought to new heights the level of opening preparation required to compete at the highest level. Fischer on the way to the World Title in 1972 studied at least as hard as they do nowdays on the openings. Recent International Tournaments show that there is still a lot of creativity possible in the opening, and some players don't work especially hard on their openings. Karpov shows that you can get by playing a limited series of systems and rely upon the middlegame for results. Fischer's obsession with fixed games is certainly as a result of personal observation during his own career (I don't quite believe it was as rife as he says but it is certain that the Russian's did agree draws with each other very frequently in those days) but the rivalry between Karpov and Kasparov makes it impossible to believe they fixed games.

I think it was a big shock to Fischer when he came back against Spassky, it is said that friends from throughout the World sent him masses of analysis that was unlooked at during that match. The sheer volume of material probably brought it home to Fischer that there was no way back to the very pinnacle of World Chess (as a student of 19th Centuary chess Fischer should have known that with Andersson's comments about his match against Morphy) but it doesn't mean that he couldn't have competed at a high level. The message from Argentina is that he has no will to do the work on the openings. His demeanour against Spassky suggested that he did enjoy competing again but this didn't last after the match, perhaps he enjoyed it too much?

One wonders what Reshevsky would have made of all this. Reshevsky struggled against Fischer throughout the 60's when Fischer's superior knowledge of openings had a direct effect on their results (remember Fischer winning in about 12 moves due to a piece of Russian analysis refuted a quite standard Sicilian setup?).

So, its all over for Fischer, he leaves a legacy of superb games, one wonderful book, and a life story packed with incident. I wouldn't be Bobby Fischer for any money. His capacity to surprise, and also shock will remain but it would be the biggest shock of all to see him play chess again.

Crowther appears to have been more interested in Fischer than in the variant he was trying to promote. I suspect that was the case with most observers in the mid-1990s.

25 October 2009

Castling Stats

In More from Mainz 2009, I quoted Alexander Grischuk, the winner of the chess960 open at the 2009 Chess Classic Mainz, on castling in chess960: 'You should not castle too quickly because you still keep the option to castle on the other side. In some positions it's totally clear to which side you will castle. Then it makes no sense to delay it.'

This made me wonder if the choice of which side to castle is consistent between chess960 and traditional chess. In other words, after castling do the Kings end up on the two sides of the board -- Kingside or Queenside (h-side or a-side in chess960 parlance) -- with the same frequency in both versions of the game. The game scores from the 2009 Chess960 Rapid World Championship (RWC), won by Nakamura, seemed to indicate that there was no castling in many games and that castling O-O-O occurred more often castling O-O. This is contrary to my experience in traditional chess and I decided to do a simple analysis.

First I looked at the games from the recent Pearl Spring tournament, won by Carlsen. In the 30 games played there I found that O-O occurred 42 times and O-O-O occurred 14 times. This means that of the 60 times the castling option was presented (30 games x 2 players per game), the players castled 56 times. In those games where the players castled, castling O-O occurred 75% of the time and castling O-O-O 25%. These results were approximately what I expected to see.

The 2009 RWC presented a different picture. In the 20 games played, O-O occurred 9 times and O-O-O occurred 14 times. This means that of the 40 castling opportunities, the players castled only 23 times, and O-O-O was played more often than O-O.

Would previous years confirm this result? The year 2008 saw a match for the Women's RWC title, with fewer games than in 2009, so I skipped to 2007. The 2007 RWC featured 22 games. The move O-O occurred 29 times and O-O-O occurred 8 times. These results were more in line with the Pearl Spring statistics.

My conclusion was that the samples were too small to be meaningful. I'll come back to this question another time when I have more data to analyze.

24 October 2009

More from Mainz 2009

Following up my post on CCM9: Nakamura, Grischuk, and Rybka, there were reports on this year's Chess Classic Mainz (CCM) from other news sources than Chessbase.com. Before I get to them, it's worth giving one more link to Chessbase -- Mainz 2009 - Schmitt: 'I suffer vicariously with Anand' -- and a quote: 'With more than sixteen years of experience in the chess business, Hans-Walter Schmitt is one of the dinosaurs in the chess organizers circuit. With all his energy, stunning ideas and passion for the game, together with his friends he has developed the Chess Classic into the best and most popular rapid chess tournament in the world.'

The Chessbase article is more about CCM's flagship rapid event than its chess960 event, although the two share a common format.

In 2007 we changed the format to a double round robin with four players and a four-game final. We wanted to be able to upgrade the Ordix Open, but we also wanted to keep the opportunity to invite certain players to Mainz. The same format is applied in the Chess960 competition, in which the challenger for the world champions is determined in the FiNet Chess960 Open.

Here's a pre-event interview with defending chess960 champion Levon Aronian from the official CCM site Chesstigers.de: You need a good feeling for harmony • Chessninja.com (aka 'The Daily Dirt') featured a couple of posts which attracted comments from the Dirt's many loyal fans: Chess in the Mainztream and Nakamura 180 in Chess960 • Chessvibes.com had several reports on the event; here's one; follow 'Tags: Chess960' for more: Aronian and Nakamura qualify for Chess960 Wch final • Post-Mainz reporting included a wrapup article from NYTimes.com on Nakamura's win over Aronian in the final: A Game With 960 Possible Openings, but an American Champ Is Unfazed • Finally, here's an audio report from the ICC's Chess.FM (webcast.chessclub.com): Grischuk post-FiNet win. Insights from the interview with Grischuk included the following.

This year I was really very lucky on the second day. I scored 5 out of 6 but I could have easily scored 1 out of 6. There were some very memorable games, with Mamedyarov especially, and also obviously in the last round the only chance for me was if Kamsky loses and I win.

I'm pretty bad in this game in the opening stage. I've really improved since my first year. You cannot say I was in bad form because I won that year the normal rapid [event], but in Fischer Random I was totally humiliated. I was losing to amateurs with no fight. Then I learned.

The first year I was playing like g4/b4, but in order to play like this successfully you have to be either Aronian or Nakamura. They look to be the only two persons who do it successfully. Kamsky does it but he tries more like f4/c4, but they are g4/b4. It works for them, but for me it was just terrible. Since then I try to play a more central approach at the starting stage.

I also learned that you should not castle too quickly because you still keep the option to castle on the other side. In some positions it's totally clear to which side you will castle. Then it makes no sense to delay it.

I'll feature a Grischuk game in a future post.

18 October 2009

Winter's (Chess960?) Proposal

Continuing with Some Numbers on Chess Book Publishing and Whistling Past the Graveyard?, the topic is chess publishing and the subtopic is books about chess openings. If chess960 eventually nukes the market segment built around opening books, what will take its place?

One idea is Wanted by Edward Winter, the doyen of chess history. Written in 1999, before chess960 was even introduced at Chess Classic Mainz, Winter's essay included the following lament.

Until the day we too 'cease publication' we shall never fully understand why so many chess writers (and, it must be assumed, so many book buyers) are primarily interested in books on individual chess openings. Is the chess public as a whole really more inspired by a book on the Semi-Slav Defence than by a comprehensive guide to Euwe's career or, even, Kasparov's? In a sane world, wouldn't at least some of the works proposed in the present article be viewed as mainstream chess literature, with openings monographs regarded as of merely minority, and ephemeral, interest?

The proposals embedded in the query -- 'a comprehensive guide to Euwe's career or, even, Kasparov's' -- are just two examples of many scattered throughout the essay. Along with 'monographs on individual players', Winter suggested 'games collections grouped around an identifying theme', 'treasures contained in old magazines', 'algebraic editions of the classics', 'books for which English translations are sorely needed', 'basic reference material', and more. It's easy to come up with many similar ideas.

When I was in my pre-teen years, I was intensely interested in baseball. On top of following my Dad's favorite team, I had a small collection of books related to the history and lore of the game. I remember passing many an hour reading and re-reading the stories about the great players, teams, and events that had taken center stage before my time. The intense interest lasted only a few years, but it established a comfortable acquaintance with the sport that has stayed with me throughout my life. Where are the books that will kindle a similar interest in young chess enthusiasts? Chess isn't just for grownups, after all. It's for everyone.

17 October 2009

Kasparov's Chess960 Proposal

In two of my recent posts -- 'I'd be on my very own from the first move' and Some Numbers on Chess Book Publishing -- I mentioned some macro changes that would sweep through the chess community if chess960 ever takes root and threatens the extinction of traditional chess openings. How can we accommodate these changes and minimize their impact?

Kasparov proposed one idea in an interview he gave shortly after he retired from chess in 2005: Garry Kasparov Interview, Part 2 (part 1 is linked at the end of the second part). The 13th World Champion said,

I’m in favor of at least investigating doing one position per year from chess960. I know the reaction is "Aahhh, horrible!" Most players think it’s terrible, saying the purpose is to start each game from scratch. I don’t think so, I think the point is to create more space for creativity. If you have a position for a year you can’t go too far in analysis. You can reach move maybe four or five, that’s a lot of room for creativity.

The purpose of the suggestion seems to be letting professional players continue with the working methods they have used for decades -- preparing opening systems in advance, committing them to memory, and playing their ideas in important games against unsuspecting opponents. It has the advantage of keeping an element of psychology in the game.

The lack of opening psychology is a noticeable disadvantage of chess960. In traditional chess a player makes a statement in playing 1.d4 instead of 1.e4, in playing the Caro Kann instead of the Sicilian, in choosing a rare side variation instead of a main line, and so on. The psychological struggle in the opening is even more important for players who meet each other regularly, like the world's elite do.

Unfortunately, a rhythm of one position per year wouldn't have much impact on the publishing business. A year is not enough time to gather experience with a particular start position, to write a book on that experience, to publish and market the book, and to use the ideas contained in the book in further competition.

A good starting point for Kasparov's proposal would be one of the 11 symmetric positions (12 positions minus RNBQKBNR) with the King and Queen on the central files that I listed in A Database of Chess960 Start Positions; for example, RNBKQBNR (SP534). Since it is the closest relative to the traditional start position (SP518), many of the ideas known to current chess theory would be naturally reused. It would also show what impact the slight change in the castling rules, described in Arbitrariness in Chess Rules, has on the overall game. This would be useful knowledge for evaluating differences between the other 479 chess960 twins.

In one of his radio interviews, Fischer scoffed at Kasparov's idea. Perhaps he reacted too hastily.


Later: A better start position to explore Kasparov's idea might be what H.J.R.Murray (see More on the Initial Position in Chess) called the 'crosswise arrangement: where the King and Queen start not on the same file, but where the King starts on the same file as the opposing Queen'. This is not a chess960 position, but still has the advantage of being unexplored opening territory.

11 October 2009

Whistling Past the Graveyard?

The graveyard of chess opening books, that is. While browsing various items about Chess960 @ Chess.com, I found the following morcel by Chess.com member FM_Eric_Schiller (comment to World Championship Computer-Assisted Predictions):-
I have to say that in my view Chess960 is no better than any other chess variant. All variants are way inferior to the true game. Chess has evolved over 1500+ years to achieve such a great balance that we have no idea what the best first move is.

Players who are too lazy to study openings may indeed prefer Chess960, but it hasn't caught on and will never do so. Chess openings are still unclear and exciting, and computers have increased the number of playable openings, not decreased them.

The Chess.com page for FM_Eric_Schiller confirms that the member is FM Eric Schiller of chess publishing fame: 'I have a full website at www.ericschiller.com, which includes samples of many of my more than 100 books, mostly of chess but a few on linguistics.' Following that URL, we find that many of the 'more than 100' books are listed on Eric Schiller's Books on Chess, while others can be located via Bookfinder.com: Searching for books where author is Eric Schiller.

Although opinions vary on the quality of Schiller's work (see Eric Schiller [Wikipedia] for a sample), here we have a bona fide contributor to the massive pile of opening books I discussed in Some Numbers on Chess Book Publishing, together with thoughts on the destiny of chess960. I imagine the thoughts are representative of the community of chess opening authors. Thank you, Dr. Schiller, for sharing.

Getting back to the specific remarks, my first comment is a reminder that chess960 is not a chess variant. It's an evolution of traditional chess as it has been played for the last several hundred years. Traditional chess is itself a subset of chess960, one of the 960 possible starting positions. The traditional start position dates to the mysterious appearance of chess over 1400 years ago, when before the battle began, armies assembled in symmetric formation facing each other across an invisible dividing line, generals in the center.

Ignoring the unsubstantiated opinion ('all variants are way inferior'), the name calling ('lazy'), and the idle speculation ('hasn't caught on and will never do so'), Schiller's objection to chess960 boils down to

  • 'we have no idea what the best first move is', and
  • 'computers have increased the number of playable openings'

This is just as valid for chess960 as it is for chess and overlooks the main reason for considering chess960: that opening theory has reached the unfortunate point where

  • the early moves of the game are based increasingly on memorization, and
  • the real struggle often starts in the late middlegame or endgame.

The message of any author of opening books is 'buy this book and follow the instructions'. The message of chess960 is 'think for yourself'. World Champion Bobby Fischer -or- FM Eric Schiller? I know which horse I'm backing.

10 October 2009

Some Numbers on Chess Book Publishing

In 'I'd be on my very own from the first move', I quoted Chess.com member DrawMaster asking, 'Why not give up completely on traditional chess?', then making three important points,
  • 'You would never waste another $20 on some nearly useless openings manual.
  • Or waste another moment trying to remember lines.
  • Or waste another thread post ruminating on the merits of the QGD or the Ruy.'

Note that the question is not about giving up completely on chess; it is about taking up chess960 and giving up on traditional chess. If this should happen -- and it's not at all certain that it will -- any obsession with specific chess openings would disappear. What then would chess writers publish, what would chess players study when they're not playing, and what would they talk about with other chess players?

The issue of chess publishing is the most critical. Along with playing and teaching, writing is a source of income for many professional and semi-professional chess players. Are books about openings really so important to the publishing industry? Let's look at the British Chess Magazine's (BCM) Chess Books & Reviews for Q3 in 2009.

  • September 2009 • 8 books reviewed, 4 on the openings : King's Indian; Trompowsky; Pirc; Secrets of Opening Surprises, Vol. 11

  • August 2009 • 9 books, 6 openings : Sicilian Dragon; Colle-Zukertort (1.d4 d5 2.Nf3 Nf6 3.e3 e6 4.Bd3 c5 5.b3); Catalan; Spanish (Ruy Lopez); Sokolsky (1.b4); Sicilian 3.Bb5

  • July 2009 • 8 books, 3 openings : Ruy Lopez; Dutch Stonewall; Sicilian

Out of 25 books reviewed over the three month period, 13 were on the openings. That implies that about half of all chess books published today have something to with openings. What are these opening books about?

Although a few opening names appear more than once in this list -- Sicilian, Ruy Lopez -- the 13 recent books cover a variety of different openings. Extend the three months over a longer period, and we start to see a lot of duplication. Taking the first opening on the list, the King's Indian, here are titles from Book Reviews on JeremySilman.com ('Our complete archive of book reviews. Dwarfs anything else on the web!').

  • BEAT THE KID by Jan Markos
  • DANGEROUS WEAPONS: THE KING'S INDIAN by Palliser, Dembo, and Flear
  • KILL KID 1 by Semko Semkov
  • KING'S INDIAN WITH h3 by Breutigam [CD-ROM]
  • OFFBEAT KING'S INDIAN by Panczyk and Ilczuk
  • PLAY THE KING'S INDIAN by Gallagher
  • SAMISCH KING'S INDIAN UNCOVERED by Cherniaev and Prokuronov

These are titles that have been reviewed in the seven or eight years that JeremySilman.com has been on the web. There are certainly others.

How profitable are these books? That is a question that only the publishers and authors can answer. My guess, based on what little I know about the chess publishing industry, is that the average number of copies sold is in the four digit range and that each copy sold makes a couple of bucks for the publisher and similar for the author.

04 October 2009

'I'd be on my very own from the first move'

Along with Chess Ratings as a Predictor of Chess960 Skill, another Chess.com forum post that captured my attention was Has it really: 'Has chess 960 become a real part of real chess like blitz and regular chess.' DrawMaster wrote,
Why not give up completely on traditional chess? You would never waste another $20 on some nearly useless openings manual. Or waste another moment trying to remember lines. Or waste another thread post ruminating on the merits of the QGD or the Ruy. Or ... • Well, the list goes on. • Then, I realized that I'd be on my very own from the first move. And that thought was decidedly scary.

Point. Counterpoint:-

  • 'Give up completely on traditional chess' • Let's not carried away with chess960. It's a complement, not a replacement, to traditional chess.
  • 'Some nearly useless openings manual' • Yes, this is a real concern that needs to be discussed intelligently.
  • 'Waste another moment trying to remember lines' • Ditto.
  • 'Waste another thread post ruminating on the merits of the QGD' • Ditto.
  • 'The list goes on' • Does it? Looks like an excellent list as it is.
  • 'I'd be on my very own from the first move' • Scary? Maybe. Exhilarating? Definitely!

Intelligent discussion, or a well-disguised facsimile, to follow.

03 October 2009

Chess Ratings as a Predictor of Chess960 Skill

After writing the short post on Chess960 @ Chess.com, I spent some time reading relevant threads on Chess.com's chess960 forum. A few of them touched on points that I hadn't encountered before, and immediately caught my interest.

The first post that interested me was "Rating too low to accept this match!" Are you kidding me!?. The initial point of the thread was a complaint about how Chess.com uses ratings to match players who have requested a game with upper/lower limits on the ratings of potential opponents. It seems that traditional chess ratings are used in the algorithm for chess960 games. I assume this is done because the chess960 service was introduced on the site a few months ago and there were no chess960 ratings.

If that were the only point in the thread, I wouldn't bring it up here. More relevant were the following comments by ReLentLess5150, who was also the originator of the thread.

'I sincerely doubt that the so-called "higher rated players" in chess 960 have as huge an advantage as the might in standard chess.' • 'Do you HONESTLY believe that ratings play that much of a role in 960!?' • 'Chess 960 is basically a free for all, and I would hazard a guess and say that the odds of a low rated versus highly rated player [at traditional chess] are probably pretty low, 1400 versus a 2200. Who would you put your money on? On the other hand, I would give the 1400 at least even money in 960.'

Despite ReLentLess's apparent unfamiliarity with the rating system -- a 1400 has almost zero chance of winning a traditional game against a 2200 (see the table 'Rating expectancies vs. differences' at the end of Chess Ratings for the odds at different rating spreads) -- the writer raises some good points.

If we're talking about chess960 ratings that have been computed only on the results of chess960 games, then the chess960 rating will be just as good a predictor of future chess960 results as the chess rating is for traditional chess results. This has nothing to do with skill at chess; it's a result of the statistical and mathematical foundation of the rating system. As Elo pointed out, his rating system is valid for any two-player competition, whether fencing, boxing, or cribbage.

Of course, cribbage ratings have no predictive value for a chess game between the same pair of adversaries, just as chess ratings have no predictive value for a boxing match. The more pertinent question is whether traditional chess ratings have any predictive value for a chess960 game. I am certain that they do.

Suppose our 1400 player survives into an endgame against the 2200 player. As I pointed out in Differences Between Chess and Chess960, a chess960 endgame is 'usually indistinguishable' from a chess endgame. I said 'usually' because we can imagine some chess960 endgames where a Bishop might be in the corner, still blocked on the diagonal by a Pawn of the same color. That is obviously the result of a chess960 opening.

What chance does the 1400 player have against the 2200 in the endgame? A little better than in the earlier phases, because the position might peter into a theoretical draw (assuming the 1400 recognizes the opportunity and steers for it), but in general, the 2200 will win due to a better grasp of endgame principles and general superiority in accurately calculating long variations.

Now suppose the 1400 player reaches a middle game against the 2200. It is very unlikely that the 1400 is going to survive that phase. The 2200 has a superior ability to calculate tactics, a better understanding of positional play, a greater familiarity with combinations, and a wider knowledge of stock positions. One, if not several, of those advantages will result in a win for the 2200.

If the 1400 is totally outclassed in both the endgame and the middle game, that leaves the opening. Unlike the 'free for all' that ReLentLess imagines, the opening is exactly the phase where the 2200's superior knowledge of positional play is likely to swamp the 1400 even before the pieces are fully developed. The choice of castling (less obvious in chess960 than it is in chess), the effective deployment of the minor pieces, and, above all, the choice of a game plan are going to leave the 1400 hopelessly confused.

The example of a 1400 against a 2200 is just that: an example. The statistical advantage of the higher rated player is the same across the entire rating scale. The example might have been a 2200 against a 2700, where the same table of 'Rating expectancies vs. differences' predicts a 96% winning chance for the higher rated player.

I'll go even further in my claim that chess ratings are good predictors of chess960 results. In chess960 the lower rated player can no longer hide behind the shield of memorized opening variations and will make a mistake even earlier than in a traditional chess game. That means the higher rated player has a greater statistical chance of winning the game, meaning that the chess960 rating difference between the two players will be even greater than the difference in their chess ratings. Chess is, after all, a game of skill rather than a game of chance, and so is chess960.

28 September 2009

Chess960 @ Chess.com

On my main blog I've mentioned several times how much I like Chess.com (see Posts with label Chess.com). I was pleased to see a few months ago that the site now offers chess960. The kickoff was announced in Chess960 Explained!, where Mr. Chess.com himself (aka Erik) explains how to find a game. See also Forums > Chess960 and Other Variants.

27 September 2009

Arbitrariness in Chess Rules

I doubt that anyone can give a real reason why SP518 (RNBQKBNR) is the accepted start position for a game of chess, rather than SP534 (RNBKQBNR), shown in the following diagram. The only difference between the two positions is that the Kings and Queens are switched. Both SP518 and SP534 have the 'royalty' located in the center and both have the other pieces starting in a formation that, given the moves of those pieces, is superbly logical.

Start Position 534

Considering the two start positions objectively, there is no real reason why the Queen should start 'on her color'. The rule could be stated just as easily 'King on his color'. The start positions of the two pieces is an arbitrary decision that makes no real difference one way or the other. If the rules of chess had been codified as 'King on his color', chess opening theory would have developed exactly as it has over the last two centuries, and all of our chess books would have opening diagrams reflecting the switch in the positions of the Kings and Queens.

In chess960 the two start positions SP518 and SP534 are not equivalent. As I pointed out in A Database of Chess960 Start Positions,

SP534 is not a simple mirror image of SP518, the traditional start position. When castling O-O or O-O-O in SP534, the King and Rook end up on exactly the same squares as they do when castling in SP518: e.g. after castling O-O, the Rook ends on f1 and the King ends on g1.

It might not be as obvious as the case with the start positions of the King and Queen, but the rules of castling in chess also contain a big dose of arbitrariness. Suppose the castling rule in traditional chess were defined as follows:-

  • when castling O-O, the King ends on f1, the Rook on e1;
  • when castling O-O-O, the King ends on b1, the Rook on c1.

Other than the observation that it is a little easier to state the informal rule that we use to describe the castling move -- 'the King moves two squares toward the Rook and the Rook hops over the King' -- the new castling rule is just as logical as the traditional rule. The new rule could be stated informally as 'the King moves one square toward the Rook on the Kingside or three squares toward the Rook on the Queenside, and the Rook hops over the King'.

If you've thought about the castling rule in traditional chess ('two squares toward the Rook'), you probably realized that castling to the two sides does not produce identical positional considerations. Castling O-O-O has the advantage that the Rook ends up on a center file (the d-file), while castling O-O has the advantage that the King is located closer to the corner where it is a little safer. After castling O-O-O, a second move (Kc1-b1) is often played to move the King closer to the corner, while after castling O-O, a second move (Rf1-e1) is often played to bring the Rook to a center file. In either case, achieving the full advantages of castling -- safety the King and activate a Rook -- often requires an additional move. (*)

Looking the same way at the new castling rule ('one square toward the Rook on the Kingside or three squares on the Queenside'), the relative merits of the two types of castling have reversed. Castling O-O-O requires an additional move to bring the Rook to the center, while castling O-O requires an additional move to bring the King toward the corner.

Now let's say we define a variant where (a) we always start RNBQKBNR, but (b) in half the games we castle using the rule 'two squares toward the Rook', while in the other half we castle using the rule 'one square toward the Rook on the Kingside or three squares on the Queenside'. We have in fact defined a game where we play SP518 in half of the games and SP534 in the other half of the games. This is because our new castling rules have created a perfect mirror of SP534, with the King always starting on e1 instead of d1.

Looking at the other 958 start positions in chess960, it's easy to see that exactly half of the positions are mirrors of the other half, where the only real difference is the castling rule. We could just as easily have defined a game where (a) the King always starts on the Kingside, but (b) in half the games we respect traditional castling (O-O ends Kg1 and Rf1, O-O-O ends Kc1 and Rd1) while in the other half we use new castling (O-O ends Kf1 and Re1, O-O-O ends Kb1 and Rc1). This would result in exactly the same game as chess960, the sole difference being that the King always starts on the Kingside!

I'm not suggesting that anyone play using this half-and-half castling rule. I can imagine endless debates about which castling rule is actually in use for a specific game. What I'm suggesting is that chess960 is really chess480*2, where '*2' (meaning 'times two') denotes the two castling variants. Even if we were to restrict the number of start positions to two -- SP518 and SP534 -- we would have essentially doubled the number of opening variations available to us in traditional chess.

To repeat the point of my previous post, Chess960 Is an Evolution of Chess. It removes the arbitrariness of traditional chess rules, thereby increasing the complexity of the opening phase.


(*): Of course, the full range of positional considerations behind castling is more complicated than what I've stated. After castling O-O, the Rook might be better placed on a square other than e1, just as after castling O-O-O, the Rook might be better placed on a square other than d1. Similar considerations apply to the best square for the castled King. These complications don't change the direction of my argument; they just show how subtle chess (or chess960) can be.

26 September 2009

Chess960 Is an Evolution of Chess

Over the last few weeks I've investigated the evolution of two important rules in chess. The first rule governs the initial position:-

The second rule governs castling:-

I didn't pick these two rules at random. Together they constitute the sole difference between traditional chess (aka SP518: RNBQKBNR) and chess960. A frequent objection to chess960 is the emotional argument, 'It's not really chess!', which is only true if we consider chess to be exactly the game defined by FIDE's Laws of Chess (appropriately called 'FIDE Chess' by certain people).

The laws are found in FIDE's Handbook under section 'E. Miscellaneous': E.I.01A. Laws of Chess, where, contrary to the belief of the 'It's not really chess!' crowd, we also find in E.I.01B. Appendices the rules of chess960, which were added earlier this year. [Am I the only person who thinks it odd that FIDE classifies the laws of chess under 'miscellaneous'?]

In my lengthy quotes from Murray on the origins of the two rules, I included his summaries on other rules that have evolved through the centuries -- the moves of the pieces, the Pawn's initial move, Pawn promotion, en passant, stalemate, the bare King. These show that the similarities between traditional chess and chess960 are more significant than the differences.

21 September 2009

Murray on the King's Leap, Italian Style

Unlike the excerpt I gave in Murray on the King's Leap, Spanish Style, I've extracted in entirety Murray's section on the Lombard (Northern Italy, including Milan) game. His notes on the King's Leap also represent a more substantial portion of the material in the section (p.461-463).

As for the mention in the last paragraph that 'details will be found on a later page', this refers to the material I covered in More on Castling in Chess.

20 September 2009

Murray on the King's Leap, Spanish Style

The material in Davidson on the King's Leap seems to have been taken mainly from Murray. In the preface to his book, Davidson wrote,
At first I was afraid that my book was to be sheer plagiarism. But I was encouraged by the discovery that if you steal your ideas from one author, that is plagiarism; whereas if you lift them from many, that is research.

If he were alive today, Davidson would undoubtedly be a keen blogger.

Murray described the King's Leap in separate sections in his chapter on 'The Mediaeval Game'. One section addressed chess in Spain, another addressed chess in Italy. Here's what he had to say about the Spanish game (p.457-461).

In fact, except for point (4) in the second part, most of the material I've excerpted has nothing to do with the King's Leap. I've left in the rest to establish the period covered, to show Murray's own sources (MS. Alf. is the Alfonso manuscript and is well described on other Web pages), and to overview the rules of the pre-modern game at that time, particularly the Queen, the Bishop, and the Queen's leap.

19 September 2009

Davidson on the King's Leap

In both The Origin of Castling and More on Castling I quoted several mentions by Murray of the King's Leap. Here's what Davidson had to say about the move in 'A Short History of Chess' (p.22):
The King's Leap. It occurred to early chess players that if in actual practice a mounted soldier could escape capture by leaping over his enemy, the King, who presumably would also be mounted, could escape in the same way. The King was surely as potent as one of his own Knights. And so there was introduced in Sanskrit chess the King's leap -- a privilege of moving like a Knight. This is still the rule in the Malay peninsula where once during the game (usually when "checkmated" -- or to escape checkmate) the King may leap like a Knight. [...] An initial two-move leap for the King was permitted in European chess down to the 13th century.

For more about Davidson, see The Origin of the Initial Position and More on the Initial Position. In his chapter on the Rook, he tied the leap to castling (p.48):

Castling. The root of castling is the King's leap [described above]. There were two forms of this leap. In the first, the King could jump once like a Knight. In the other, he had the privilege of going two squares on his first move. The latter form of the "King's leap" was the practice in European chess down to the 13th century.

In the North African variety of Arabic chess, the King was put into a safe corner by a two-stage procedure. First he moved into the second rank. Then the Rook was brought into the King's original square and simultaneously the King went to the Rook's corner. This was the embryo of modern castling and its development from there proceeded along logical lines. [...]

From North Africa [castling] crossed the Mediterranean along the trade routes and its first appearance in Europe was in Italy toward the close of the 15th century. For a while, Italy was the only country in Europe which used castling in chess play. As the Arabic crescent waxed around North Africa and crossed Gibraltar, the chess practices of the Moslems entered Spain and in the 16th century castling was the rule in Spanish chess. By this time, however, the Arabs had consolidated the maneuver into a single move, so that one-move castling was practiced on the Iberian peninsula and two-move castling on the Italian peninsula.

By 1630 castling was known in France, Britain, and Germany, though because of its dual ancestry, there was for a while some confusion as to the technic. [...] By the end of the 17th century, castling in the modern manner was a fixed rule of chess.

Davidson had a tendency to explain historical facts by speculative musings (e.g. 'It occurred to early chess players...' above). I've removed most of these from the quotes I selected.