In January of this year, Ifuu Publishing transcribed and published a limited edition of "Igo Hatsuyôron, All / Reiwa transcription", based on what is considered THE ONLY SURVIVING COPY of Inoue Dôsetsu Inseki's "Igo Hatsuyôron" in Japan.

Please find attached problem #120, including English translations of the original text in old Japanese.

Please note that the "normal" text on the problems follows the pattern
>>> "Black/White first, (ko,) result"
but IH120 has
>>> "Black first"
only!!!

And please don't overlook the further clue to the problem )

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The really most difficult Go problem ever: https://igohatsuyoron120.de/index.htm
Igo Hatsuyōron #120 (really solved by KataGo)

For other readers, this new book is the result of research by 7-dan pro Kuwamoto Shinpei, who actually retired to become a local pro in Tottori. He found the original in a Buddhist library where it had been badly damaged by insects. The restoration is obviously a little tentative but there is interesting extra metadata on some other problems. I confess to finding the extra clue (which I assume to refer to the Kongming/Zhongda Three Kingdoms title) too obscure.

But what I liked about Kuwamoto's work was that he found clues to how Dosetsu seems to have worked. Here is a lovely example. It is Problem 83 in the Fujisawa edition.



It seems that Dosetsu got the idea for this problem from an actual game he played Honinbo Dochi. It was Game 6 of their 10-game match (game 1706-03-28a in the GoGoD database). Dosetsu played the triangled stone and Dochi had the good sense to answer it. He evidently saw a variation that merits a 5-star rating from Takagi Shoichi ("prefectural champion" standard, or about amateur 8-dan). Which tells us something about Dochi, too - he was just a young teenager (15 then but he had become 4-dan pro at age 11 or 12).

The game adds a theme (seki) that doesn't come up in the lines normally shown for the solution.

Sorry, but I was referring to the explicit reference to the single Black stone that was captured earlier, which apparently did not survive further copying.

+ + + + + + + + + +

Zhuge Liang == Black and Sima Yi == White ?

Historically, the latter has triumphed over the former (says Wikipedia).

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The really most difficult Go problem ever: https://igohatsuyoron120.de/index.htm
Igo Hatsuyōron #120 (really solved by KataGo)

I think we'd normally expect White to be given first, and Kongming's reputation was certainly greater than Zhongda's. But when Kongming died, Zhongda was besieging his army. As I recall, it seems that the likeliest story is that Kongming simply died of illness (a story overlaid by superstition because a meteorite was said to have fallen near the Shu army and would obviously have been taken as an omen). The leaderless Shu army then gave up. But the rival emperor wrote something about Kongming losing the battle and fatally vomiting blood. As always, history is written by the victors. Whether any of that provides a clue I know not. But normally problem titles do offer a clue or a description of the starting position.

Other titles in the book relate to the same Three Kingdoms period, and it was around this time that yin-yang first became a "thing", so maybe it was just that Dosetsu had a fascination with that period (the Japanese yo element in the book name being Chinese yang, and his preface includes references to yin.

Updated the Igo Hatsuyôron 120 website with

• a new chapter about the new "Reiwa Complete Reprint Edition" and
• a new section "2024" on the "The Solution" page, showing several new sequences found by KataGo in games between Karl's 40b network from 2022 and my 60b network still in progress.

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The really most difficult Go problem ever: https://igohatsuyoron120.de/index.htm
Igo Hatsuyōron #120 (really solved by KataGo)