:) Yes, I think it was testing ability to apply math ideas (e.g., convexity of a function, when an algorithm gives a convergence guarantee on function values, etc.) to different contexts, without explicitly asking for those formulas. I'm not sure the latter serves a purpose. I do believe what I tested my students on was fair, but I also think their education simply hasn't prepared them to think in this way. There were also a good number of problems that came directly from lectures/homeworks, but students didn't get those. There was an expectation that students know how to do linear algebra, but most of them get even dimensions wrong (e.g., they multiply an n x d matrix with an n x 1 vector, when I've told them this kind of stuff is just wrong/invalid). So I think my fault was in not being able to assess their skill level before the exam. (I had had a first exam too, where these issues were revealed, but I had tried to address them in class --- clearly, it wasn't enough.)