In principle, all of theoretical computer science. In practice, a subset that includes primarily parts of computational geometry, but also optimization problems on graphs and the like and polynomial time computability of equilibria in games and some economic models.
A selection of some papers that I have placed online should give a better idea. For a more complete list, check out DBLP's list of my publications.
In Fall 2020, I am teaching undergraduate algorithms (CS:3330). The material is all within ICON, I am not able to maintain a public webpage.
Courses I have taught since Spring 2005:
2:30--4:00 Mon, 1:00--2:30 Tue. Email me for Zoom Info.Kasturi Varadarajan ( firstname-lastname AT uiowa DOT edu )