any password generation scheme where this is relevant is a bad idea
I disagree; as the post mentions, sometimes considerations such as memorability come into play. One example might be choosing random English sentences as passwords. You might do that by choosing a random parse tree of a certain size. But some English sentences have ambiguous parses, i.e. they’ll have multiple ways to generate them. You *could* try to sample to avoid this problem, but it becomes pretty tricky to do that carefully. If you instead find the “most ambiguous sentence” in your set, you can get a lower bound on the safety of your scheme.
I disagree; as the post mentions, sometimes considerations such as memorability come into play. One example might be choosing random English sentences as passwords. You might do that by choosing a random parse tree of a certain size. But some English sentences have ambiguous parses, i.e. they’ll have multiple ways to generate them. You *could* try to sample to avoid this problem, but it becomes pretty tricky to do that carefully. If you instead find the “most ambiguous sentence” in your set, you can get a lower bound on the safety of your scheme.