Congratulations! Our principal investigator Prof. Franz Baader (TU Dresden) won the Best Paper Award at the 14th International Symposium on Foundations of Information and Knowledge Systems (FoIKS 2026). The awarded paper is “An Order-Theoretic View on Optimal Repairs and Complete Sets of Unifiers”.

An Order-Theoretic View on Optimal Repairs and Complete Sets of Unifiers

Abstract

The optimal repair property, which says that there is a finite set of optimal (i.e., entailment-maximal) repairs that covers all repairs, has turned out to be useful both in the context of ontology engineering and in belief change. We provide abstract order-theoretic conditions that guarantee the existence of finite sets of optimal repairs covering all repairs, and illustrate their use with abstract examples as well as with more practical examples from the realm of Description Logic (DL). The order-theoretic view on optimal repairs also reveals that there is a strong similarity between the optimal repair property and the existence of a finite complete set of unifiers for unification modulo equational theories.

Applying Siekmann’s proposal to divide unification problems into the unification types unitary, finitary, infinitary, and zero to repair problems, we obtain a more fine-grained classification of repair problems. For the DL examples introduced in this paper, we observe that types unitary, finitary and zero can occur, but none of these examples provides us with an infinitary repair problem. However, we also show that unification problems can actually be viewed as repair problems in the abstract framework introduced in our previous work on contractions based on optimal repairs. Thus, within this framework, known results on unification types of certain equational theories provide us with examples of repair problems of these types.

The full paper is available here.

FoIKS 2026

The FoIKS symposia provide a biennial forum for presenting and discussing theoretical and applied research on information and knowledge systems. The goal is to bring together researchers with an interest in this subject, share research experiences, promote collaboration and identify new issues and directions for future research. The 14th edition took place in Hannover, Germany from March 23–26, 2026. It was hosted by the Institute for Theoretical Computer Science at the Leibniz Universität Hannover. Springer, the Artificial Intelligence Journal and EurAI were sponsors. Learn more about the conference here.