The Igo Hatsuyōron is a classical Japanese collection of Go problems, written 300 years ago, in 1713. In 1982, Fujisawa Hideyuki 9p published the "lost" problem 120 (found by Araki Naomi in an old edition), and produced a solution with his study group. The main results were also given in an English-language article in Go World, Autumn 1982-issue, edition 29.
By the beginning of the 21st century, several other proposed solutions could be found, in both Chinese (Weiqi Fayanglun), and Korean (Wiki Balyangron), not only in books, but also on the Internet. The sequences reported as "correct" differed from each other in some details.
They all shared one thing: At a very critical moment they did not take into account the strongest resistance by White. This fact was uncovered by Joachim Meinhardt, a German Kyu player, after several years of work, and published by me in 2005 in the Deutsche Go-Zeitung (= German Go-Journal) under the headline "The really most difficult Go problem ever". It said that the goal of "Black to play, and win" had not been reached.
In 2007, at the suggestion of Benjamin Teuber 6d, Yamada Shinji 6p was kind enough to spend some of his valuable time on Joachim's finding. Yamada Shinji found a further improvement for White, making more problems for Black.
At the end of 2007, I discovered a move for Black, which was not mentioned in the literature to date. This move - a guzumi - gains three points for Black. Perhaps it can re-open the path to a win for Black?
In the following years I worked intensively on the variations following my guzumi. Yoon YoungSun 8p was kind enough to give me the endgame sequences for some essential ones.
In 2009, Harry Fearnley from the United Kingdom brought a follow-up move into play that, combined with the guzumi, gives Black a further gain of four points (in one of two significant main variations).
In June 2011, we published the first edition of this book as a summary of our work, and of what we knew to have been published up to mid 2010. Our thanks go to Gunnar Dickfeld from Brett-und-Stein (= "board-and-stone") publishing house, who made this first publication possible.
This problem is not a simple life-and-death problem. It is a complicated whole-board problem. We think that it is the most interesting, and difficult, problem in any of the classical problem books. For that we have to thank Inoue Dōsetsu Inseki.
It is really unusual (perhaps unique) to have a whole book about a single problem. Our reason for writing the book was that we wanted to obtain a definitive solution to the problem. We know that we have found aspects, which were missed in previously published solutions, and thought that we had to publish our proposed solution, so that others could look for errors in ours, and so arrive at the correct solution.
Furthermore, the problem itself is very unusual, and we thought that some others might also enjoy getting a fuller understanding of its complexity.
Because the problem is a whole-board problem, we have to be concerned about the territorial result - this is normal. Yes, this makes it more like analysing a "normal" game. As is usual in traditional problem books, the problem says simply "Black to play". This assumes the addition of "... and get the best result" - in this case this must mean "... get the best final score - at least win, rather than lose". There are two possible large Black sacrifices. White will choose which group to capture. Black's problem is to make sure that whichever one White captures, White will still lose!
In 2010 Cheng Xiaoliu 6p published his second book on Igo Hatsuyōron. We could not consider this book in our first edition. Many of his results confirmed our earlier ideas. Nevertheless, our assessment of the correct solution is not affected by Cheng's newer findings. We have used this anniversary edition to integrate results of his newer analysis. In addition, we have included discussions of further variations from other sources known to us.
We have now completed our investigations into the correct order of moves in the top right corner, after the guzumi.
We also added some new results on the first moves of the solution, and on some obscure aspects, which arise during the building of the hanezeki in the lower right corner.
Our latest investigations relate to two very irritating semeai, found by Joachim, which could arise in the professional line of play. We edited the corresponding chapter after the first printing of a special edition in March 2012. We never imagined that - from the known comments - something that looked so simple could become very confusing, and complicated.
Our special thanks go to Kang KyoungNang 7d, and Professor Prof. Jeong SooHyun 9p as well as his students at Myongji University in Seoul, who - despite being extremely busy with their usual tasks at the University - were so very kind to work long and intensively with our solution and give us valuable information, especially concerning our new results. Kang KyoungNang helped us with variations for the very first moves and established the contact with the Myongji University. The contributions of Professor Prof. Jeong SooHyun and his students brought us past the guzumi, and allowed us to focus on the correct line of play for the endgame on the left side.
In May 2012, I was very pleased to get the opportunity to meet Kobayashi Chizu 5p, and Ōhashi Hirofumi 6p, at the Nihon Kiin during a stay in Japan. Ōhashi Hirofumi did not seem to be uninterested in our work (collected in a second, largely extended, but unpublished, edition) and also had prepared some suggestions about the correct order of moves for filling the nakade on the left side.
We are very delighted that Michael Redmond 9p has shown great interest in our work. He got in touch with the problem during a teaching visit of the United Kingdom in Spring 2013. We owe Michael Redmond many valuable comments and very interesting insights into the professional mindset.
Michael Redmond validated the strongest tenuki variation after Black's guzumi, including improvements for many of our sub-variations. He also drew our attention to a kikashi in the bamboo joint in the upper right corner, which was not previously noticed by us.
As the second edition of our work the third edition - celebrating the 300th anniversary of Igo Hatsuyōron - exists in a bound form in only a few copies, most of which are reserved to the authors.
We are therefore delighted that Anders Kierulf has added our book to the library of his SmartGo Books. So, much more interested Go players than ever should be able to find access to its very specific content.
To further enable the reader to facilitate access to the certainly very complex matter, we have decided to extend the explanations of the structure of the problem and its internal dependencies significantly, and also to expand the theoretical explanations in the back of the book.
This reconstruction of the book led to a division of the solution into three distinctive sections, and to the introduction of "Technical Notes" to enable an in-depth study for those who are particularly interested into the problem.
After a striking "Summary of Our Solution" as an entry we start our book by presenting our solution (ending with a three-point victory for Black) and its variations.
We continue by presenting the latest professional solution (by Cheng), and its specific variations. This is a sequence of professionally published best moves for both sides, but ending with a jigo only.
This is followed by an historical review, both of the development of knowledge published by professionals as well as of our own findings.
Subsequently, we describe the impact of the move found by Joachim, which puts all the professional solutions in question. We then proceed to the analysis of my bad shape move.
The latter part of the book describes special structural elements of the problem. Some readers may want to read some chapters - e.g. on approach-move liberties, or on hanezeki - out of sequence, as they first encounter these topics in the book.
The last year was devoted to further analytic work on Joachim's Ko-Semeai. We tried to reduce the complexity that is inherent in this semeai by starting from a later position, so to say put the cart before the horse. This, combined with the comparison with our previous approaches, led to the awareness that we accidentally had been too inattentive with respect to the correct order of moves (but which did not effect the major results). The extensive description of the complex issues increased the size of the book to such an extent that it became necessary to divide the book into two volumes for printing.
Volume I of this forth edition of our book contains our solution, and its variations. Volume II is devoted to the professional solution, the historical description of our studies, as well as the more theoretical parts.
Most likely, we have not yet identified all the places that we would have to edit, due to our most recent findings.
Please understand that, in the light of the degree of difficulty and complexity of the problem, we have shown some longer move sequences repeatedly at various points throughout the book. Also - with the exception of most ko sequences - we have tried to show all moves in diagrams, so avoiding the use of "x at y" when a stone is played on the point where another one was captured.
We ask for your kind understanding that we will use more Japanese Go terms than you might be accustomed to in English Go books nowadays. Igo Hatsuyōron is a Japanese classic; and in its problem 120, there are several key moves that are essential for either the solution, or important sub-variations. We prefer to highlight these very special moves by using their original Japanese name.
We hope this book helps to find a reliable solution to this most difficult of all Go problems. We would be delighted to receive any comments, criticisms, or suggestions. Please do this via our e-mail account "igohatsuyoron@gmail.com".
Readers who wanted to enjoy an easier, and simpler, introduction into the problem, might consider starting with our book "Igo Hatsuyōron 120 - An Elephant in Slices".
In 2012, I visited the classical Japanese landscape garden at Katsura Imperial Villa in Kyoto, where even one lifespan does not seem to be sufficient to explore all of its beauty. Igo Hatsuyōron 120 seems to me to resemble such a typical Japanese garden. Nothing can be added, nothing can be changed, and nothing can be taken away, without destroying the harmony of the garden (i.e. the solution here).
No one but a genius will be able to construct such a garden and to find the primary path for walking through it. However, after enjoying the garden for several years, we simply asked "Has this special viewing line ever been recognized before?" And, surprisingly enough, apparently nobody had seen it before.
Igo Hatsuyōron's problems were designed to push forward the frontiers of Go technique by presenting the most difficult problems which people could actually solve. In problem 120, the exact position of each stone on the board matters, and the various parts and aspects are so well integrated with each other that it is hard to believe in coincidence, so making the problem an artistic masterpiece. We play Go because we admire such great depth and skill, as shown by Inoue Dōsetsu Inseki.
We would like the reader to view this book as an encouragement to push one's analytic efforts to the limits of one's abilities. If you not only enjoy the experience, but find that it is enlightening, and leads to an improvement in your Go playing, we will be very pleased.
Berlin, April 2015
Thomas Redecker