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Description Logics (DLs) is a family of formalisms used to represent knowledge of a domain. They are equipped with a formal logic-based semantics. Knowledge representation systems based on description logics provide various inference capabilities that deduce implicit knowledge from the explicitly represented knowledge.

A Proof Theory for Description Logics introduces Sequent Calculi and Natural Deduction for some DLs (ALC, ALCQ). Cut-elimination and Normalization are proved for the calculi. The author argues that such systems can improve the extraction of computational content from DLs proofs for explanation purposes.

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Introduction.- Background.- Sequent Calculus for ALC.- Comparing SCalc with other ALC Deduction Systems.- Natural Deduction for ALC.- A Proof Theory for ALCQI.- Proofs and Explanations.- A Prototype Theorem Prover.- Conclusion.

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