Researchers cannot obtain all the structural information about real-world data required by theoretical conditions in practice.

“And in practice we will never have that information for our real data. In practice we just have, maybe we have a clue, right, I think we can oftentimes kind of estimate, for instance, we can often estimate how many clusters there could be in our data with r relatively simple uh methods. But we can't really have very deep information into our structures because ultimately it's the the real world and we still approximately everything as theoretical cows.”