His primary academic interests are combinatorics on words, formal languages, automata theory, and algorithmic number theory.
en.wikipedia.org Indeed, in algebraic combinatorics, association schemes provide a unified approach to many topics, for example combinatorial designs and coding theory.
en.wikipedia.org His research focuses on computational complexity theory, algorithms, combinatorics, and finite groups, with an emphasis on the interactions between these fields.
en.wikipedia.org The second part expands on enumerative combinatorics, or the systematic numeration of objects.
en.wikipedia.org A very closely related topic is geometric group theory, which today largely subsumes combinatorial group theory, using techniques from outside combinatorics besides.
en.wikipedia.org