Mid-2013, after the release of our 300^th anniversary issue, just when we thought we had finally made it, we were directed to a wooden box buried in the sand.

Carelessly we opened it, and freed the nightmare of a very surprising and extremely intricate Ko. Quite obviously it must have been Pandora, who had lost this box. Only after the investment of another two years, and a further several hundred pages, we were able to close the lid again.

The printed version of our work has now about 1,100 pages, which made it necessary to be divided into two volumes. It is intended to publish a hardcover version later this year, but before ...

... you may enjoy the entire contents here.
Volume 1 ...

... contains the main path of our solution, and a very wild bunch of nested variations. In addition, various overviews are included, of which we hope that they clarify the structure of the problem.

A hardcover edition is available with .

Volume II ...

... begins with what we know about professional solutions to the problem.

The largest part is the detailed representation of the evolution of our investigations.

Finally, we explain some structural aspects of the problem.

A hardcover edition is available with .

Those who shy away from the more or less scientific approach in our "large" books are invited to choose this "tiny" one, published in early 2015.

Enjoy a journey through time — look over the shoulder of Dosetsu and get a picture of how he composed his masterpiece.

This book presents this difficult problem in 120 slices. Each aspect of Igo Hatsuyōron 120 is explained using relatively simple individual problems, so you can understand the entire puzzle.

We here followed well-known wisdom ...
“How do you eat an elephant?” is the usual management consultant's reply when being asked how to manage a huge project. We think that this is also applicible for Igo Hatsuyōron 120.

This book is available with SmartGo Books (on the linked page, please select the browser's address line, and click "enter").

This book celebrates the problem-collection’s 300^th anniversary and was - published in mid-2013 - the most comprehensive collection of information about this stunning problem.

It discusses what we believe to be the solution to the problem, including an in-depth treatment of the failed lines. All move sequences are explained in great detail. The same is true for the additional work on theoretical issues that are fundamental to the problem (e.g. hanezeki, approach-move liberties, and ko).

This book is available with SmartGo Books (on the linked page, please select the browser's address line, and click "enter"), and includes the text in English and German. Its content is four times as extensive as with our first book.

All significant findings are already included in our first book on the problem, published in mid-2011.

It summarizes our early research and reveals our findings - by mid-2011 - apparently destroying the known solutions.

The book - bilingual in German, and English - is available with Brett und Stein (= "Board and Stone") publishing house.

Only for documentation purposes, we keep our "frozen" old site on here:

If you have any suggestions, questions or comments, please do not hesitate to contact us!

For this purpose, we have created an e-mail-account with gmail.com: igohatsuyoron120

We very much regret that it is beyond our technical capabilities to integrate here in place a forum or a blog.

Therefore, if you want to discuss in public, please be so kind to use the thread
"The most difficult problem ever. Igo Hatsuyoron 120" with Life in 19x19:

We will respond to you there.