معرفی
Lars Kristiansen is Professor II (part-time Professor) at the Department of Mathematics, University of Oslo. His research centres on the intersection of mathematical logic, computability theory, and computational complexity, with recent emphasis on computable analysis, weak first-order theories, subrecursive degree structures, and implicit computational complexity.
Research Interests
- Computable Analysis: Representations and computational complexity of irrational and real numbers.
- Weak First-Order Theories: Decidability, interpretability and fragments of concatenation theories.
- Subrecursive Degree Theory: Fine structure of honest subrecursive degrees and the Grzegorczyk hierarchy.
- Implicit Computational Complexity: Reversible computing, type systems that capture complexity classes, and resource-bounded program analysis.
Across more than 50 refereed publications since 1996, a clear trend emerges: an early focus on subrecursive hierarchies and honest degrees evolved into an intensive study of the computational content of real number representations and the logical strength of weak arithmetics. Recent work (2023-2025) deepens this agenda, analysing the complexity of converting between alternative representations of reals and the degree structures that these induce.
Scientific Output
While no named awards are listed, Kristiansen’s contributions are disseminated in top venues such as Bulletin of Symbolic Logic, Annals of Pure and Applied Logic, Archive for Mathematical Logic, Science of Computer Programming, and leading LNCS conferences. His work is frequently co-authored with Amir Ben-Amram, Jakob Grue Simonsen, Juvenal Murwanashyaka, Ivan Georgiev, and Neil D. Jones, indicating active collaborative networks in both logic and theoretical computer science.
Research Groups & Collaborations
- Logic research group at the University of Oslo
- Data and Knowledge Management (DKM) group
