F. Mohr, T. Lettmann, E. Hüllermeier, and M. D. Wever, “Programmatic Task Network Planning,” in Proceedings of the 1st ICAPS Workshop on Hierarchical Planning, Delft, Netherlands, 2018, pp. 31–39.

M.-C. Jakobs, J. Krämer, D. van Straaten, and T. Lettmann, “Certiû01cation Matters for Service Markets,” in The Ninth International Conferences on Advanced Service Computing (SERVICE COMPUTATION), 2017, pp. 7–12.

F. Mohr, T. Lettmann, and E. Hüllermeier, “Planning with Independent Task Networks,” in Proc. 40th Annual German Conference on Advances in Artificial Intelligence (KI 2017), 2017, pp. 193–206.

F. Mohr, T. Lettmann, and H. Kleine Büning, “Reducing Nondeterminism in Automated Service Composition,” in Proceedings of the 6th International Conference on Service Oriented Computing and Applications (SOCA), 2013, pp. 154–161.

T. Lettmann, M. Baumann, M. Eberling, and T. Kemmerich, “Modeling Agents and Agent Systems,” Transactions on Computational Collective Intelligence V, pp. 157–181, 2011.

B. Stein, O. Niggemann, and T. Lettmann, “Speeding Up Model-based Diagnosis by a Heuristic Approach to Solving SAT,” in AIA ’06: Proceedings of the 24th IASTED International Conference on Artificial Intelligence and Applications, 2006, pp. 273--278.

H. Kleine Büning and T. Lettmann, “Resolution remains hard under equivalence,” Discrete Applied Mathematics, pp. 139–148, 1999.

T. Lettmann and H. Kleine Büning, Propositional Logicf: Deduction and Algorithms. Cambridge Univ. Press, 1999.

H. Kleine Büning and T. Lettmann, “Learning a representation for optimizable formulas,” in Lecture Notes in Computer Science, Berlin, Heidelberg, 1996.

H. Kleine Büning and T. Lettmann, Aussagenlogik - Deduktion und Algorithmen. Teubner, 1994.

A. Flögel, H. Kleine Büning, and T. Lettmann, “On the restricted equivalence for subclasses of propositional logic,” RAIRO - Theoretical Informatics and Applications, pp. 327–340, 1993.

B. I. Dahn, T. Lettmann, and W. Schönfeld, ILFA Interface Concept, vol. 193. ´Heidelberg: Wissenschaftliche Zentrum der IBM Deutschland , 1991.

H. Kleine Büning, T. Lettmann, and E. W. Mayr, “Projections of vector addition system reachability sets are semilinear,” Theoretical Computer Science, pp. 343–350, 1989.

H. Kleine Büning and T. Lettmann, “Perspektiven für die Logikprogrammierung,” in Workshop Wissensrepräsentation in Expertensystemen, 1988, pp. 56–78.

H. K. Büning and T. Lettmann, “Representation independent query and update operations on propositional definite Horn formulas,” in Computation Theory and Logic, E. Börger, Ed. Berlin, Heidelberg, 1987, pp. 208–223.

H. Kleine Büning and T. Lettmann, “Classes of first order formulas under various satisfiability definitions,” in 8th International Conference on Automated Deduction, Berlin, Heidelberg, 1986.