Wilfried Sieg

Proof theory of (1) subsystems of classical analysis (second-order number theory) and arithmetic and (2) of calculi for natural reasoning. The work under (2) is the foundation for human-centered automated proof search. Conceptual analysis of the notions of human computability (Turing) and machine computability (Kolmogorov, Uspenskii, Gandy). History of modern mathematics and logic, in particular, (1) Hilbert's conception of foundations of mathematics, beginning with its origins in the work of Dedekind and (2) Gödel's incompleteness theorems and their deep connection to the notion of human computability.