Markov Chains
Probability for dependent events, memoryless systems
First read about this topic back in pre-final year of my undergrad, under the Speech Processing course by AV, wish this was the highlight of the course instead of wasting half of the semester brushing up on signals and systems, which we already covered under the Digital Signal Processing course prior.
But hey, not to be disappointed, we have a lot of time to ourselves to re-visit these topics.