I think understanding has to be related to generalisation, because we need to clearly separate it from simple memorisation. In math, for example, being able to

I think understanding has to be related to generalisation, because we need to clearly separate it from simple memorisation. In math, for example, being able to solve equations not in the training set would show generalisation. But understanding is mostly a receptive process. On the other hand, intelligence is about acting, and is an emissive process. It will select the next action trying to achieve its goals. Intelligence also needs to generalise from few examples and work in new contexts, otherwise it is not really intelligent, just a custom solution for a custom problem. Compression alone is not equal to intelligence because compression is looking at past data, so it needs to learn only past patterns, while intelligence is oriented forward and needs to reserve capacity for continual learning.