### These are some unpublished notes that I wrote, some of them might
develop into papers later.

- "The Complexity of Satisfiability Problems with Two
Occurrences", 4 pages, December 2003.

- "Exponential Incomparability of Tree-like and Ordered Resolution", 3 pages, December 2000, revised April 2001.

- "The Lattice of Propositional Proof
Systems", 2 pages, February 1997, revised December 1998.

- "On Threshold Logic and Cutting Planes
Proofs" (with Peter Clote), 8 pages, June 1997.

- "A Note on Eventually Complete Models of Type
Theory and Quine's New Foundations" (with Ulrich
Weigand), 6 pages, February 1997.

- "Elements Definable by Nonstandard
$\Sigma_n$-Formulae in Models of Peano Arithmetic", 4
pages, August 1995.

- "The Axiom of Infinity in Zermelo Set
Theory", 6 pages, January 1993.

Back to my homepage.