Hello all,
Hnishy fairly recently (in 2023?) marked a large number of problems as unsound, on the problem page itself, because of there being multiple solutions. I think it's a pity this was done, because on a problem page there should be rather little information - often as little as possible. Saying there are multiple ways to live is a sort of a hint.
Also, I personally do not think there is a consensus, at least among the English-language Go community, to call a problem unsound just because it has more than one solution. This is also my interpretation of what we currently have in the page Tsumego Conventions.
Moving forward, I would prefer for the comment (that there are multiple solutions) to be moved to the solution page of the tsumego - and I wouldn't use the word unsound either.
If we had wiki categories or tags then perhaps such tsumegos could be added to a new category "tsumegos with multiple solutions".
Happy to hear what others think about this, particularly SL librarians.
I don't have a stand on this issue, but would like to state that in both Chinese and Japanese, there is a specific term for failed life-and-death problem constructions: 失题 (Simplified Chinese) / 失題 (Traditional Chinese/Japanese), literally "missed problem". This term is used when a problem has either (i) no solutions, or (ii) more than one solution.
In printed Chinese problem books, it is common to see a statement on the problem itself stating that "this is a "missed problem" with two solutions". I suppose this is the same for Japanese - I don't know the history, but I have a feeling that the Chinese Go community had imported the "missed problem" concept from the Japanese.
As hnishy is a Japanese, I am not surprised why he did things the way he did. Given my background, I had been treating his labeling of "unsound" problems as nothing out of the ordinary as well.