••• HomeRybka engineRybka 4 book
Rybka engine
Demo version
Purchase Rybka
Rybka 4 book
Rybka 3 user area
FAQ for v 2.x

Rybka 4 opening book for Aquarium

The following articles were written by Dadi Jonsson for his monthly column on "Chess Cafe".

The subject of this article is the Rybka 4 Aquarium opening book, which was prepared by Rybka team member Jiri Dufek.

Jiri Dufek

Jiri has been playing chess since the age of six, when his grandfather taught him how to play. He holds a title of national master, as well as being an international master of correspondence chess. His hobbies include computer chess and collecting chess books. He has authored the opening books for Rybka's official competitions where his choice of solid but active repertoire, often involving little explored lines, proved to be a great success. He has also been very successful in freestyle chess, with his latest triumph being a victory in the Mundial Chess tournament earlier this year. Jiri wrote the book Bijte francouzskou! (Beating the French) along with his friend and long-time associate IM Roman Chytilek. Jiri no longer plays over-the-board chess, but focuses instead on opening analysis and chess analysis in general. Jiri is an IT system administrator by profession. With this background, and his obvious passion for chess, Jiri is clearly an ideal team member of any chess or computer-chess team.

Jiri was kind enough to answer my questions regarding the new Rybka 4 opening book, but I couldn't resist also asking him about his work for Veselin Topalov in the world championship match against Viswanathan Anand and the analysis tools he uses in the match.

Q: You are in the enviable position of being a member of the Rybka team as well as Topalov's analysis team. Additionally, you are the only new member of the Topalov team in his match against Anand. What is the story behind you joining the Topalov team?

A: As a reward for my result in the Mundial Chess freestyle tournament, I was invited to the Linares tournament site to play a game against Veselin Topalov. During my stay in Linares I met Veselin's seconds - Jan Smeets and Erwin l'Ami. After my game against Topalov, which ended in a draw, I also got a chance to speak to the master himself.

Veselin Topalov vs. Jiri Dufek

We discussed chess in general, openings, chess engines and the differences between human chess and the world of chess engines. Shortly after I returned home from the trip, I got an invitation from Silvio Danailov to join Topalov's team for his match against Vishy Anand.

Q: I'm sure that your expert opening knowledge played a big role in Topalov's decision to ask you to join his team. However, the times are changing and knowledge of computers and advanced analysis methods plays a bigger role now than in any previous world championship match. Do you think that your extensive experience and knowledge in these areas also played a role in Topalov's decision?

A: I think this question is more complicated than it looks at first sight. Firstly, Topalov and grandmasters in general have their own ideas on how to play the openings. Their priorities are completely different from those normally applied when preparing opening books for chess engine matches. There is no interest at all in long lines which may lead to a draw after dozens of precise moves. Memorizing lines is difficult and time-consuming, with little hope of practical reward. It's simply bad investment of match preparation time. Therefore a good chess engine book author is not automatically a good assistant for human opening preparation. He must be flexible and adapt to the different requirements.

Secondly, I often checked existing analysis, looking for improvements or used "my methods" to analyze lines, which were considered important for the match. Every time my conclusions agreed with the analysis of the other team members. The quality of opening analysis at this level is extremely high, but of course every team member makes an important contribution to the preparations. I have the greatest respect for the other team members. They have proven time and again that they are second to none in opening preparations and more than once they have stunned the chess world with their opening novelties.

Thirdly, my computer background has allowed me to provide IT support for our team. You could say that I have been the team's "IT Department".

Veselin Topalov and Jiri Dufek

Q: Your Rybka 4 Aquarium opening book will be released soon. It's clear that you put a huge amount of work into the book.

A: Yes, I put a lot of work into it. It helps that I find it really interesting to analyze unknown positions and ideas from chess books, chess practice or computer games and find my own solutions. Today's opening preparation is very deep. In some cases players know their lines from the opening all the way to the endgame. A less prepared opponent will probably lose his way somewhere in the middlegame against such preparation. Things are looking even worse in computer games - long lines, often 50 moves or more, leading to a draw are similar to pre-arranged draws in human games.

The technical advances mean that opening analysis is very different from what it used to be a few years ago, not to mention a few decades ago. However, even with today's amazing computer tools, the work of the modern opening book author is still very demanding.

My method of creating a strong opening book consists of several steps. Assuming you already have a good database, the first step is the selection of games. Making a good hand-typed book is impossible. The selected games serve as the "raw material," and generate the initial version of the book. This step may only require a few hours of work. The next step is to fine-tune the move priorities. This is a very time consuming task, and in the case of the Rybka Aquarium book, it took a few weeks.

Testing the book is an independent process. First you run a test and then you look at the results and try to find weak points in the book. After further analysis you may find some improvements, which require updates to the book and another test cycle must be run. This process will take a few days.

Last, but not least is the creative phase of making an opening book. Here you need to find new ideas and get a deeper understanding of the lines in the book. One recurring question in this phase is why engines give a low evaluation, or play badly positions which are very good according to my own understanding of the position. This phase is not only very time consuming, it also needs a lot of creativity and manual interaction and guiding of the engine analysis.

Q: You made a very successful opening book for Rybka-Cluster. Did some secrets from that book make it into the Rybka Aquarium opening book?

Rybka Cluster currently runs on 13 powerful computers

A: Yes, I moved priorities from the tournament book which I used with Rybka-Cluster to the Aquarium book. I think I'm not far off when I say, that the Aquarium book includes around 95% of the Rybka-Cluster book which I used in official tournaments. However, the Aquarium book is much bigger and contains a lot of new material and analysis, up-to-date games etc.

Q: How would you describe your opening book? Is it a "narrow" book, covering a few selected openings deeply or is it a "wide" book containing most openings that arise in practice?

A: Generally, the book is relatively wide covering many openings and variations. I wanted to offer two different ways of playing every opening, but sometimes I ended up with only one, because I felt that it was the best way to handle the position.

A narrow book might score pretty well in the short term, and I would have chosen that path if a high score in engine matches was my only goal. However, I wanted the Rybka Aquarium book to address the needs of a much wider audience which means that a much greater number of openings needs to be covered. This is why I added many openings which are popular in human play. The variations are color coded with green color (recommended moves), red (not recommended), blue (recommended for human tournaments but not computer tournaments) and black (neutral moves). Aquarium allows users to juggle the move priorities based on the color codes, so it's easy, for instance, to use the book as a "tournament book" in chess engine matches.

Although I have a wide range of users in mind for this opening book, I'm not sure that it will suit everyone. The first group I am targeting is of course Rybka users and chess engine fans in general. They will find up-to-date information about their openings. The second group would be everyone who wants something new, new opening ideas or new opening setups. Last but not least, I tried to make it a thoroughly researched and up to date, general opening guide for the tournament player. Although I think it might even be useful for grandmasters, I think they haven't caught on to the opening developments in the chess engine world and still prefer their current methods of opening preparation. On the other hand I would be extremely interested in getting feedback from grandmasters. Perhaps it will be useful for my next opening book.

From the white size, the main repertoire of the Rybka Aquarium book is based on the Sicilian Najdorf Variation with 6.Be2/h3/Be3/Bg5, Caro-Kann with 3.e5, Ruy Lopez, French with 3.Nc3 and 3.e5, Catalan, classical King's Indian Defence with 9.Ne1 and 10.Be3, the Exchange Variation of the Grünfeld Defence, Nimzo-Indian Defence with 4.f4, etc.

For black there is the Sicilian Kan Variation (e6+a6), which proved to be very successful for Rybka-Cluster in official tournaments, the Sicilian Najdorf Variation and the Rauzer Variation with Bd7, Caro-Kann and Ruy Lopez (Berlin Wall and Jaenisch). After 1.d4 there is the Grünfeld Defence and a lot of Slav Defence (Chebanenko 4…a6) and Semi-Slav analysis as well as the Nimzo-Indian Defence - where I used my openings from the Rybka-Cluster opening book.

Q: When Jeroen Noomen's opening book for Aquarium was released he said that "IDeA is the best opening book tool at this moment." Do you use IDeA in your opening analysis?

A: Yes, for opening analysis there is no better solution, because it allows you to find some very interesting, "non-human" continuations which would be hard to find otherwise. I emphasize quality over quantity, so I prefer to give the engines a longer time for the analysis of each position - this mean that I use automatic IDeA tree expansion and as the analysis progresses I check analysis tree, compare the results with my own notes and decide which positions are important and analyze them more deeply. For analyzing the middlegame I still use my own, much simpler methods, to decide which move to play, but my IDeA analysis is constantly running.

Q: Do you use the new features of IDeA in Aquarium, such as remote engines?

A: I really like the option to use remote chess engines. It is small revolution for IDeA and it really works! For critical positions I run the analysis from my PC connected to approximately 40 remote engines, located in four different places of the world. For smaller projects I often use slower computers with only local engines.

Q: Did you develop the Rybka 4 Aquarium book using the opening book tools of Aquarium itself?

A: I use Aquarium both because it allows very fast addition and editing moves in the book and while I am doing that I can have chess engines analyzing one or more positions in the background. Aquarium has many advantages and useful features for the serious player, such as for analyzing individual positions or whole games; it's also good for basic work with databases and of course the option to use remote engines for analysis. On the other hand, features such as playing against the engine are of no use to me, regardless of the GUI.

Q: Which opening line did you spend the most time on?

A: It's very hard to answer. Probably the Sicilian Najdorf was the most time consuming, but still i am not 100% sure about truth in this opening.

I probably got the biggest kick out of analyzing the Jaenisch Gambit in Ruy Lopez, because very often the best moves according to the chess engine are not really the best.

But this is not all. I added about 700 variations to the book in different openings, many of which are seldom seen in tournament books. The main purpose was to make the Rybka Aquarium book more useful for players. In other words, there are continuation of sidelines, which improved existing theory or recent games - look and you will see!

Q: Can you show us a few interesting novelties from the book?

A: Sure. There are so many novelties to choose from, but I'll start by showing my oldest novelty, which dates all the way back to 2004.

A16. English Opening

1. Nf3 Nf6 2. c4 g6 3. Nc3 d5 4. Qa4+ c6 5. cxd5 Nxd5 6. Qd4 f6 7. e4 e5 8.
Nxe5 Nxc3 9. Qxc3 Qe7 10. Nf3 Qxe4+

This line is now out of fashion and I can't wait any longer to show my novelty.

11.Kd1 ! +=

A30. English Opening, Hedgehog System

The Hedgehog is very popular at all levels of play. However, recent research shows that black is facing a lot of problems. Here are two examples.

1. c4 c5 2. Nf3 Nf6 3. Nc3 e6 4. g3 b6 5. Bg2 Bb7 6. O-O Be7 7. Re1 a6 8. e4 d6
9. d4 cxd4 10. Nxd4 Qc7 11. Be3 Nbd7 12. Rc1 O-O 13. f4 Rfe8 14. g4 Nc5 15. Bf2
g6 16. b4 Rad8


Here is another Hedgehog novelty:

1. c4 c5 2. Nf3 Nf6 3. Nc3 e6 4. g3 b6 5. Bg2 Bb7 6. O-O Be7 7. Re1 a6 8. e4 d6
9. d4 cxd4 10. Nxd4 Qc7 11. Be3 Nbd7 12. Rc1 O-O 13. f4 Rac8 14. Bf2 Rfe8 15.
e5 Bxg2 16. exf6 Ba8 17. fxe7 Qb7 18. Kf1 Qg2+ 19. Ke2 e5 20. Rg1 Qh3


A65: Benoni Defence

I am a very big fan and supporter of the Benoni, but now the only top player who likes it is GM Gashimov. There is a recent theoretical book about interesting ideas in the Benoni and I checked few of them. However, let's first look at a very aggressive line:
1. d4 Nf6 2. c4 c5 3. d5 e6 4. Nf3 exd5 5. cxd5 d6 6. Nc3 g6 7. e4 Bg7 8. h3 a6 9. a4 Nbd7 10. Bd3 Nh5 11. O-O Ne5 12. Be2 Nxf3+ 13. Bxf3 Qh4

And now the rook lift 14.Ra3! looks very unpleasant for black.

B80: Sicilian Defence

I wanted to pass over the Sicilian Najdorf, but it was not possible, of course. It was really a big torture for me. At the end I found a totally new way of playing one of the main lines, which is now under big pressure.

1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 a6 6. Be3 e6 7. f3 b5 8. Qd2
Nbd7 9. g4 Nb6 10. a4 Nc4 11. Bxc4 bxc4 12. g5 Nd7 13. f4 Qc7 14. O-O

And now


C06: French Defence

I am a big fan of the French Defence. However, in recent months black's life has not been so simple. Here is another source of worry for black. - a little bishop move and black has problems to solve.

1. e4 e6 2. d4 d5 3. Nd2 Nf6 4. e5 Nfd7 5. Bd3 c5 6. c3 Nc6 7. Ne2 cxd4 8. cxd4
f6 9. exf6 Nxf6 10. O-O Bd6 11. Nf3 Qb6 12. Bf4 Bxf4 13. Nxf4 O-O 14. Qd2 g6


C63: Ruy Lopez. Jaenisch Gambit

The Rybka Aquarium book includes a full coverage of the Jaenisch Gambit - everything is engine-checked and I made a lot of new analysis to support this interesting opening. Here are some "normal" (remember that this is the Jaenisch!) positions covered by the book:

With compensation



C92: Ruy Lopez. Zaitsev Variation

From time to time I tested my book on Playchess. I was surprised, when I found the following line to be very popular.

1. e4 e5 2. Nf3 Nc6 3. Bb5 a6 4. Ba4 Nf6 5. O-O Be7 6. Re1 b5 7. Bb3 d6 8. c3
O-O 9. h3 Bb7 10. d4 Re8 11. Nbd2 Bf8 12. a4 h6 13. Bc2 exd4 14. cxd4 Nb4 15.
Bb1 c5 16. d5 Nd7 17. Ra3 Nb6 18. a5 Nd7

This looks pretty dubious for black. However, black scored about 66% after the "normal" continuation 19.Nf1 f5! When I first saw this method of playing, I felt that there had to be a simple countermeasure. I think that I succeeded in finding a simple solution, although finding it took more time and effort than I had expected.

19.Nh2! c4 20.Rg3! with very strong attack, but you can check the full analysis after 19.Nh2 in the book.

D27: Queen's Gambit Accepted

The Queen's Gambit Accepted is very popular nowadays, and often white players choose strange sidelines, because the mainline is holding for black. This is not true after:

1. d4 d5 2. c4 dxc4 3. Nf3 Nf6 4. e3 e6 5. Bxc4 c5 6. O-O a6 7. Bb3 b5 8. a4 b4
9. e4 Bb7 10. e5 Ne4 11. Nbd2 Nxd2 12. Bxd2 cxd4 13. Ng5 Be7 14. Qh5 Bxg5 15.
Bxg5 Qd7

Here white has the subtle move 16.Rfd1! and you can check the Rybka Aquarium book to see that life is very hard for black after 13.Ng5.

D44: Semi-Slav, Botvinnik Variation

The Botvinnik system has been a popular opening for the last 30 years. The theoretical debate is very, very deep and it looks like it will soon end in a simple endgame. The Rybka Aquarium Book includes the latest development of this line. After the moves

1. d4 d5 2. c4 c6 3. Nf3 Nf6 4. Nc3 e6 5. Bg5 dxc4 6. e4 b5 7. e5 h6 8. Bh4 g5
9. Nxg5 hxg5 10. Bxg5 Nbd7 11. g3 Bb7 12. Bg2 Qb6 13. exf6 O-O-O 14. O-O c5 15.
d5 b4 16. Na4 Qb5 17. a3 Nb8 18. axb4 cxb4 19. Qg4 Bxd5 20. Rfc1 Nc6 21. Bxd5
Rxd5 22. Rxc4 Rxg5 23. Qd4 Kb8 24. Rxc6 Rxg3+ 25. fxg3 Qxc6 26. Rd1 Qc7 27. Kf1
Rh5 28. Qd8+ Qc8 29. b3 Rd5 30. Rxd5 exd5 31. Qxd5 Qa6+ 32. Kg2 Qe2+ 33. Kh3
Qf1+ 34. Kg4 Qe2+ 35. Kg5 Qe3+ 36. Kh4 Qh6+ 37. Kg4 Qg6+ 38. Kf3 Qxf6+ 39. Ke4 Bd6
, your engine will probably show something around 0.00, but do you really want to play this position as black over the board?

D85: Grünfeld Defence, Exchange Variation

The system with Rb1 and Be2 in the Grünfeld is still very dangerous for black. Many theoreticians have liked the system with Be5-c7-a5. However, in the recent months black has faced a lot of trouble here. I did my best to revitalize this line.

1. d4 Nf6 2. c4 g6 3. Nc3 d5 4. cxd5 Nxd5 5. e4 Nxc3 6. bxc3 Bg7 7. Nf3 c5 8.Rb1 O-O 9. Be2 Nc6 10. d5 Ne5 11. Nxe5 Bxe5 12. Qd2 e6 13. f4 Bc7 14. O-O exd515. exd5 Ba5

For example, 16. d6 Rb8 17. Ba3 Bf5 18. Rbc1 Rc8 19. Bf3 Qd7 20. Rcd1 Rfe8 21. Rfe1
Rxe1+ 22. Rxe1 Bd8 23. h3 h5 24. Bb2

24…c4! =

D97: Grünfeld Defence

The system with 7…a6 is the main weapon. One of the key positions arises after the moves

1. d4 Nf6 2. c4 g6 3. Nc3 d5 4. Nf3 Bg7 5. Qb3 dxc4 6. Qxc4 O-O 7. e4 a6 8. e5
b5 9. Qb3 Nfd7 10. h4 c5 11. e6 c4 12. Qd1 Nb6 13. exf7+ Rxf7 14. h5 Nc6 15.
hxg6 hxg6 16. Be3 Bf5 17. Ng5 Rf6 (17..Nxd4!) 18. g4 Be6 19. Nce4 Bd5

However, white now has a devastating continuation.

20.Bg2! Nb4 21.Ke2!! +/-

E04: Catalan Opening

The Catalan is very popular nowadays and after the world championship match between Anand and Topalov, it will get even more supporters! The Rybka Aquarium book contains many ideas and novelties in this opening, one of them being

1. d4 d5 2. c4 e6 3. Nf3 Nf6 4. g3 dxc4 5. Bg2 c6 6. Ne5 Bb4+ 7. Bd2 Qxd4 8. Bxb4 Qxe5 9. Na3 b5 10. Bd6 Qxb2 11. O-O Nd5 12. e4 Nc3 13. Qh5 Nd7 14. e5 Bb7 15. Qg5 f6 16. exf6 O-O-O 17. fxg7 Rhg8

18.Rae1 with attack.

E12: Queen's Indian Defence, Petrosian Variation

The old Petrosian recipe for handling the Queen's Indian Defence is not popular nowadays, but from time to time black tries too hard to win against this solid system and risks too much. This is line is an example:

1. d4 Nf6 2. c4 e6 3. Nf3 b6 4. a3 Bb7 5. Nc3 Ne4 6. Nxe4 Bxe4 7. Nd2 Bb7 8. e4
Qf6 9. d5 Bc5 10. Nf3 Qg6 11. b4 Qxe4+ 12. Be2 Be7 13. O-O Bf6

After 14.h3 exd5 15.Bd3 Bxa1 16.Bxe4 dxe4 17.Bf4 0-0 18.Nh2! black is lost.

(The following installation instructions are from the column one month later)


The Rybka 4 Aquarium Opening Book uses a standard Windows setup program to install the book. If you bought the download version, you must start by downloading the setup program (about 1.2GB in size). As always when installing updates or new features, you should exit Aquarium before starting the installation. When the download is complete, double-click the downloaded file to start the installation.

While the setup program is running, it shows you where it is installing the opening book. The installation path is highlighted in the image above. Since I use a separate folder for the Aquarium program files and the data files (AquariumData), the opening book is installed in C:AquariumDataATrees Rybka4Book.

Viewing the Opening Book

Once the installation is finished, start Aquarium and switch to the Sandbox. Select the Tree tab in the ribbon and click the leftmost button to display a list of available tree configurations.

The opening book contains thirteen columns of data. Some of them are only of interest to those who will use it for playing chess engine games, but most of the columns are intended for chess players who are studying the opening. I will describe each column in detail.

There is one new feature for displaying trees in Aquarium 4 that is used in the Rybka 4 Aquarium Opening Book. Several columns in the tree window can now be grouped under a single heading. The next screenshot shows an example where the three columns based on the Hugebase database are displayed under a single heading.

This feature was added for the practical reason that it allows more columns to be displayed in the same space.

The leftmost column in the opening book is the "Move" column. It shows the moves in the book and the move colors. When I wrote about the use of move colors in Introduction to Tree Configurations , I said

"A text description is given for each color in Aquarium, but you should not take those descriptions too literally and use the colors in whatever way suits you best. Dagh Nielsen, for example, preferred to call green moves "Approved" instead of "Good" and red moves "Inferior" instead of "Bad." For other colors he used the description you see in Aquarium."

The Rybka 4 Aquarium Opening Book is intended both for chess engine play and human players, and this is reflected in how Jiri Dufek used the colors to classify the moves:

Green is used for moves recommended by Jiri for both chess engines and human players. The screenshot above shows three green moves (after 1.e4): 1...c5, 1...e5 and 1...c6.

Red is a move that is not recommended or out of the scope of this opening book. The reason is not necessarily that it is a bad move, it is just that the book is not an opening encyclopedia, although it is relatively wide and covers many openings. Jiri explained in the interview with ChessOK Cafe last month: "I wanted to offer two different ways of playing every opening, but sometimes I ended up with only one, because I felt that it was the best way to handle the position." In the example shown above, the move 1...d5 (Scandinavian Defense) is colored red, which is a good example of a red move that is not necessarily bad.

Blue moves are recommended for human tournaments (in addition to green moves), but not computer tournaments. The moves 1...e6 (French Defense) and 1...d6 (Pirc Defense) are blue in the example.

Black is used for neutral moves. They are not played in engine matches unless there are no green moves in the position.

The flags column ("flg") is not used in the opening book.

The next set of columns in the tree window are the "Rybka4" columns.

First, note the small, downward pointing triangle in the upper left corner. It shows that the data in the tree window is ordered by the leftmost column in this group. Clicking the title reverses the order. Clicking the title of another column orders the data by that column.

This group of columns is based on the game database that Jiri used as "raw material" to generate the initial version of the book (see last month's interview with Jiri). He began with high-level correspondence games (Elo rating over 2300), but added more games, including chess engine games, as he continued working on the book. The first column shows the number of games where the corresponding move was played, then we see how successful that move was and the third column shows the average rating of players that played this move. Since the database contained computer games, the ratings displayed in this column are often quite high.

The next column is the CAP column. This is based on chess engine analysis of the position after the move in the move column. The evaluations are mostly based on Rybka 3. This column, like many others in the opening book, can be helpful when looking for interesting ideas to explore in the opening. Sometimes looking at the evaluation by itself may raise some questions, but more often it is the comparison of columns, based on different sources of data that can give new ideas.

Next we encounter the "Hugebase" group of columns.

This group is based on over four million games (almost exclusively played by human players) - the Hugebase database. The first column is the number of games where the corresponding move has been played. The second column is the success rate for the move and the third column shows when the move was last played.

The "2009/10" shows Hugebase statistics for recent games - games played in 2009 and 2010.

These two columns correspond to the first two columns in the "Rybka4" and "Hugebase" groups: Number of games and success percentage. Since Hugebase contains a large selection of older games (even going back a few centuries), it doesn't tell which openings are popular and successful now. That's the purpose of the "2009/10" group.

The "Corr/ICCF" is yet another group of statistics columns, this time based on high-level chess correspondence games. This is one more step in the direction of adapting Aquarium to the needs of correspondence players (see Correspondence Chess with Aquarium), but the data is also of interest to other players. The quality of games played in recent years by strong correspondence players is very high. Many organizations, including ICCF, allow the use of chess engines so you can be sure that the statistics are based on games of high quality. This makes the comparison with the "Rybka4," "Hugebase" and "2009/10" groups interesting. Now, if you actually play in ICCF or other chess correspondence events, this data will be of particular interest to you.

Finally, the "Play %" column is used for chess engine play and determines the relative frequency of moves played by the engines.

Using the Data

Instead of relying on a single source of data, the Rybka 4 Aquarium Opening Book allows you to compare and draw your own conclusions based on the comparison of five different sources of data. Sometimes you will see positions where there is a fairly good agreement between the statistics and you will probably not see any reason to doubt that they are correct. In other positions you will see different "best moves" depending on the column you are viewing. The following position is an example where there is considerable difference between the statistics.

The moves leading to this position are 1.e4 c5 2.Nf3 d6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 a6 6.Be3 e5 7.Nb3 Be6.

The following screenshot shows the relevant columns from the Rybka 4 Aquarium book for this position.

The most common move by far is 8.f3, but 8.f4 is also often played and these are the two green moves in the Rybka 4 book. If you are studying this opening, you might want to choose one of these moves for inclusion in your repertoire, but which one?

You can start by comparing how successful these two moves have been in practice. If you look at the Rybka4 column group, you will see that 8.f4 has been much more successful than 8.f3 (66% vs. 58%) and the statistics are equally good for 8.f4 in human games (Hugebase: 60% vs. 52%). However, if you look at the results in high-level correspondence games, you see a completely different picture and 8.f4 scores lower than 8.f3 (Corr/ICCF: 52% vs. 59%). In this case the number of 8.f4 games is so low (twenty-nine) that you might not want to trust the statistics for that move. Finally, the Rybka evaluation in the CAP column gives both moves the same evaluation, and in recent human games (2009/10) both moves have scored equally well, but also here there are only a few games with 8.f4.

After examining this data, you can decide if you want to choose the most popular move or spend some time on examining 8.f4 to find out why it scores so well both in a blend of human/computer games and over the board games. If you are looking for interesting ideas to explore in the opening, you would probably want to have a closer look at 8.f4.

If you are really looking for novelties, you should not hesitate to explore even the red moves in the opening book, when the statistics or CAP evaluation indicate that they might be interesting. Here is one example in the Philidor Defense, 1.e4 e5 2.Nf3 d6 3.d4 exd4 4.Nxd4 Nf6 5.Nc3 Be7 6.Bf4 O-O 7. Qd2 c6 8.O-O-O b5 9.f3 b4: If we look at the Rybka4 and CAP columns in the Rybka 4 Aquarium Opening Book, they show us the following information:

The most common move in this position is 10.Nb1. Other moves in the book are colored red. One of them, 10.Na4, has only been played three times, but it has been quite successful and scored eighty-three percent. Normally you would ignore statistics based on so few games, but here we can see how helpful the additional data in the opening book can be. Looking at the CAP evaluations, we see that the evaluation of 10.Nb1 is only +0.07, but 10.Na4 has a much higher evaluation: +0.68. With this additional information, 10.Na4 starts to look like a very interesting move! If you see similar statistics in the opening book for a position in your favorite opening, you should definitely have a closer look. Perhaps you will surprise your opponent the next time you play the opening!

Using the Book in Engine Competitions

The general rule in Aquarium is that when you need a particular feature, it is available where you are going to use it. A good example of this is the selection of an opening book for an engine competition.

When you create a new engine match, you can select the opening books for the engines in the "Match properties" dialog box. In the screenshot shown above, I am creating a match between Rybka 3 and Rybka 4 and both engines will use the Rybka 4 book to select their opening moves.

Similarly, when creating a new engine tournament, the book options are right there in the "Tournament properties" dialog box.

In this example, all the engines in the tournament will use the Rybka 4 Opening Book and "Maximum book moves" is set to eight. This means that after the first eight moves they will stop using the book and start to calculate their moves.

Using the Book When Playing

When playing against the computer and you want the chess engine to use the Rybka 4 book, there are two ways to do that. In both cases you start by switching to Play view.

If you want to access all the play options before starting a game, you can do so by selecting "Options" from the drop-down menu on the "New Game" button that displays the "Play options" dialog box.

Here, I have selected the Rybka 4 Opening Book and set "Max book moves" to zero, which means that Aquarium will select moves from the book as long as there are moves available. After that the engine takes over.

Another simple method of choosing an opening book, when playing against the computer, is to click the small downward pointing triangle in the title bar of the tree window as shown below.

A list of all available tree configurations will be displayed, allowing you to pick the opening book you want the computer to use. Note that if you are playing in fun mode, you can switch opening books even after the game has started.

Using the Book When Viewing a Game

There are two methods to select and view the Rybka 4 Opening Book in the tree window while you are examining a game in the Sandbox or in Database view.

The first method is to select the Tree tab in the ribbon and click the leftmost button to display a list of available tree configurations. This method was demonstrated above, after the Rybka 4 Aquarium book had been installed.

The other method is to click the small triangle in the title bar of the tree window. It is the same method as was described above, when playing against the engine.


FM Andrey Terekhov commented on last month's column as follows:

"I read your interview with Jiri Dufek with great interest. The part where he demonstrates improvements in his opening book for Rybka was especially fascinating for me. It is so broad that it covers quite a few of the openings that I am playing, even though I mostly play side lines. In particular, I was amazed to see the first diagram, from the anti-Gruenfeld line of the English Opening [A16], and the novelty that Jiri suggested: 11.Kd1! +=.

"The funny thing is that I had this position over-the-board in one of my tournament games sixteen years ago … and I made exactly that move! It was in the championship of Peterhof, which is a suburb of St. Petersburg, Russia. I managed to win the game very quickly and was quite proud with my "non-standard" approach. However, the game was not rated and never made it into any databases. About a year ago, I found it in my notes and decided to analyze it. Actually, I was quite disappointed to find out that White has only a small advantage, as during the game I believed that 11.Kd1 leads to a nearly winning position!"

This month Jiri Dufek replies:

Thank you for your response and the interesting game. Generally, I think that finding new moves is getting harder every year. It seems that everything has been played before. Of course this is not completely true, but very often a move that was previously played in a game is analyzed and in some way reevaluated at a later date.

It is interesting that you played 11.Kd1 sixteen years ago and it is a good example of how everything seems to have been played before - and in this case the evaluation remains the same after all this time.

I found this idea around six or eight years ago and later I shared it with Roman Chytilek. A few years later he told me that he had played this move against David Navara (probably in 2007-2008) in some local blitz tournament and lost after a hard struggle, but David probably knew this move. Since this line disappeared from chess practice, there is no reason to keep this interesting move a secret any more.

I think that there is only one way for Black to respond: 11.Kd1 Nd7 12.Bc4 Kd8 13.d3!? Qg4

The final evaluation of position is somewhere between += and +/-, but for the ChessOK Cafe article I preferred the first one, because +/- is little bit optimistic. It is probably better to give += for engine games and +/- from a human perspective. I believe that you will find more interesting ideas in the Rybka 4 book.

Purchasing the Rybka 4 book for Aquarium

The Rybka 4 book for Aquarium is available through ChessOK (=Convekta), or any other shop selling ChessOK products. You can purchase it online e.g. at the ChessOK shop:

Rybka 4 Aquarium Opening Book by Jiri Dufek (DVD)

Rybka 4 Aquarium Opening Book by Jiri Dufek (Download)

Rybka 4 opening book for Chessbase

The Rybka 4 opening book is also available for Chessbase in .ctg-Format.
More information about it can be found on Chessbase's website in two articles:

First article

Second article