Unveröffentlichte Arbeiten
- "Tautological Axioms in Tree-Like k-DNF Resolution", Februar 2022.
- "The Complexity of Satisfiability Problems with Two Occurrences", Dezember 2003.
- "Exponential Incomparability of Tree-like and Ordered Resolution", Dezember 2000, revidiert April 2001.
- "The Lattice of Propositional Proof Systems", Februar 1997, revidiert Dezember 1998.
- "On Threshold Logic and Cutting Planes Proofs" (mit Peter Clote), Juni 1997.
- "A Note on Eventually Complete Models of Type Theory and Quine's New Foundations" (mit Ulrich Weigand), Februar 1997.
- "Elements Definable by Nonstandard $\Sigma_n$-Formulae in Models of Peano Arithmetic", August 1995.
- "The Axiom of Infinity in Zermelo Set Theory", Januar 1993.