Specific interests include:

temporal logics
satisfiability
program semantics
second-order monadic logic
automata theory
well-quasi-orderings
non-classical logics
models of computation
term rewriting
equational logic
model checking
termination of programs
philosophical logic
 hybrid systems
program verification
 proof theory
theory of concurrency
theory of artificial intelligence
automated deduction
models of continuous time relational database theory
logic programming
reactive systems
program synthesis
knowledge representation
abstract interpretation
program slicing