Logic
Both propositional logic and predicate logic, and Prolog.
Minimum Message Length (MML)
A Bayesian method of carrying out
Artificial Intelligence (AI) / Inductive Inference (II) /
Machine Learning (ML) / Statistical Inference.
Programming Languages
Interesting, weird or historical computer programming languages.
Semantics
Denotational Semantics, a way of defining the semantics (meaning)
of computer programming languages and
of computer programs written in them.