Real-Time Multipushdown and Multicounter
Automata Networks and Hierarchies
by Lionel E. Deimel

I received my baccalaureate degree from the University of Chicago. I was a physics major who thought I might become a designer of electronic circuitry. I had long been interested in computer hardware and even built my own flip-flops in high school. I didn’t have the resources to construct anything useful, however.

Almost by accident, I took a computer course at Chicago, which gave me my first formal introduction to computers. I was fascinated by the logical design of computing machinery and discovered that I had a strong aptitude for programming. The course led to my decision to pursue computer science rather than physics in graduate school. After being accepted by several graduate computer programs, I chose to matriculate at Georgia Institute of Technology.

At Chicago, I had attended a physics department seminar about John von Neumann’s theory of self-reproducing automata. I learned more about automata, abstract computing devices, in my coursework in the Department of Information and Computer Science at Georgia Tech. This led me to propose a thesis topic in automata theory.

My dissertation, Real-Time Multipushdown and Multicounter Automata Networks and Hierarchies, generalized existing automata models and investigated their capabilities. The reader can be excused for thinking that my dissertation looks like it came out of a math department. In fact, I spent hours outside walking around my house thinking about how to convert hypotheses into theorems. The product of my graduate career is highly mathematical.

Like many dissertations, mine failed to change the world. Automata theory made contributions to computer science, but progress in the field proceeded in different directions. My profession interest followed those other directions.

— LED, 9/13/2023