My student +John Moeller (moeller.fyi) just defended his Ph.D thesis today! and yes, there was a (rubber) snake-fighting element to the defense.
John's dissertation work is in machine learning, but his publications span a wider range. He started off with a rather hard problem: attempting to formulate a natural notion of range spaces in a negatively-curved space. And as if dealing with Riemannian geometry wasn't bad enough, he was also involved in finding approximate near neighbors in Bregman spaces. He's also been instrumental in my more recent work in algorithmic fairness.
But John's true interests lie in machine learning, specifically kernels. He came up with a nice geometric formulation of kernel learning by way of the multiplicative weight update method. He then took this formulation and extended it to localized kernel learning (where you don't need each kernel to work with all points - think of it like a soft clustering of kernels).
Most recently, he's also explored the interface between kernels and neural nets, as part of a larger effort to understand neural nets. This is also a way of doing kernel learning, in a "smoother" way via Bochner's theorem.
It's a great body of work that required mastery of a range of different mathematical constructs and algorithmic techniques. Congratulations, John!