That is precisely my point. They were not considered "unsolvable" (i.e. impossible to solve), they were considered "unsolved" (i.e. not solved yet) and were pre

That is precisely my point. They were not considered "unsolvable" (i.e. impossible to solve), they were considered "unsolved" (i.e. not solved yet) and were presented as such. Do you really need me to explain distinctions in meaning here?