Many thanks go to all the people (that we know of), who have worked on the problem so far, and whose valuable results have laid the foundations for our amateur research.
First of all, there is Fujisawa Hideyuki, also known as Fujisawa Hideyuki Shūkō, who worked on this problem, which is apparently not included in previous published editions of Igo Hatsuyōron. Together with Yasuda Yasutoshi 9p, who developed the hanezeki sequence, and Fujisawa Hideyuki Kajinari 8p, they worked for a total of approximately 1,000 hours to find their solution, which was finally published in Fujisawa Hideyuki's 1982 book.
Additionally, he published an article in the Go World, on this problem alone, from which the Western world got knowledge of the new problem.
Cheng found an additional exchange in the hanezeki sequence, worth two points, and published it in his 1988 book.
Merlijn Kuin 6d introduced "Dōsetsu's problem" to goproblems.com. He also included some additional variations, not to be found in the books so far. Additional variations were also developed by Denis Feldmann, who presented the problem on his website. On goproblems.com Joachim Meinhardt had discussed the question of a probably missing Black stone, long before he came up with his idea of the "late" oki.
However, it was not before he got knowledge from some changes in the order of moves, shown on the website of Jêrôme Hubert, when Joachim Meinhardt realized that his "late" oki was the decisive death blow to the professional solutions of the problem. Its territorial advantage leads White to victory.
During a stay in Korea, Yamada Shinji was so kind as to spend some of his valuable time on our results so far. He confirmed the validity of Joachim's oki, and, additionally, found the tsuke in the top left corner. Many thanks go to Benjamin Teuber 6d, who made the contact possible.
Yoon YoungSun 8p was so kind as to give us several sequences, concerning the endgame in some tenuki-variations after my guzumi.
In his second book on the problem collection in 2010, Cheng published extensions and variations of his solution to this problem (included in his 1988 book). This edition caused some of our assumptions (e.g. the second throw-in) to be confirmed professionally. In 2011, Kang KyoungNang 7d helped us with variations for the very first moves. She also established the contact with the Myongji University.
Professor Prof. Jeong SooHyun as well as his students at the Myongji University in Seoul have been working long and intensively with our solution and were so especially kind to provide us with very valuable information. They also confirmed my guzumi.
Kobayashi Chizu 5p established the contact to Ōhashi Hirofumi 6p, who corrected the previously-used nakade-filling sequence, and hoped to study our book further.
Michael Redmond allowed us very interesting insights into professional thinking, and also provided us with very valuable contributions to technical aspects of the problem.
Joachim has worked tirelessly to reduce our potential move-alternatives to those that really worked. His gift for anticipating far-distant effects - maybe as many as 100 moves later - has been a great help in doing this.
Last, but not least, there is Harry Fearnley, who joined our amateur research team. His hasami-tsuke in the top right corner - advantageous only in conjunction with my guzumi - provided our solution with a decisive territorial advantage for Black. Now it was possible again to claim the existence of a Black prisoner at the very beginning of this middle-game Tsume-Go. Harry also worked hard to make my "German English" readable for native speakers.
I bow my head in deep respect for Inoue Dōsetsu Inseki, whose genius was the source of the really most difficult Go problem ever created.
Should there be any flaw in this book, it goes without saying that only me (but none of the other people mentioned above) can be blamed.
Thomas Redecker