This paper presents a method for combining logic programs with description logic (DL) to enable interoperability between the Semantic Web's rule-based and ontology-based approaches. The authors define a new intermediate knowledge representation called Description Logic Programs (DLP), which is a fragment of first-order logic (FOL) and closely related to Description Horn Logic (DHL). DLP provides a significant degree of expressiveness, surpassing the RDF Schema fragment of DL. The paper shows how to perform DLP-fusion, a bidirectional translation between DL and logic programs (LP). This allows for "building rules on top of ontologies" and "building ontologies on top of rules." DLP-fusion enables efficient LP inferencing algorithms to be used for reasoning over large-scale DL ontologies. The authors analyze the expressive intersection of DL and LP, showing that both are strict subsets of FOL. They define DHL as a subset of this intersection, and DLP as a related fragment. DHL is used to map DL to def-Horn, a fragment of FOL, and vice versa. This mapping allows for the translation of DL axioms into def-Horn rules and vice versa. The paper discusses the expressive power of DHL, showing that it includes RDFS and a subset of DAML+OIL corresponding to a simple frame language. DHL is also shown to support the extension of this language to include equivalence of conjunctions of atomic classes and axioms corresponding to DAML+OIL transitive property and inverse property statements. The authors conclude that DLP is an expressive subset of DL and can be viewed as an expressive fragment of def-Horn. The paper emphasizes the importance of DLP-fusion for enabling interoperability between DL and LP, allowing for the use of efficient LP inferencing algorithms for reasoning over large-scale DL ontologies.This paper presents a method for combining logic programs with description logic (DL) to enable interoperability between the Semantic Web's rule-based and ontology-based approaches. The authors define a new intermediate knowledge representation called Description Logic Programs (DLP), which is a fragment of first-order logic (FOL) and closely related to Description Horn Logic (DHL). DLP provides a significant degree of expressiveness, surpassing the RDF Schema fragment of DL. The paper shows how to perform DLP-fusion, a bidirectional translation between DL and logic programs (LP). This allows for "building rules on top of ontologies" and "building ontologies on top of rules." DLP-fusion enables efficient LP inferencing algorithms to be used for reasoning over large-scale DL ontologies. The authors analyze the expressive intersection of DL and LP, showing that both are strict subsets of FOL. They define DHL as a subset of this intersection, and DLP as a related fragment. DHL is used to map DL to def-Horn, a fragment of FOL, and vice versa. This mapping allows for the translation of DL axioms into def-Horn rules and vice versa. The paper discusses the expressive power of DHL, showing that it includes RDFS and a subset of DAML+OIL corresponding to a simple frame language. DHL is also shown to support the extension of this language to include equivalence of conjunctions of atomic classes and axioms corresponding to DAML+OIL transitive property and inverse property statements. The authors conclude that DLP is an expressive subset of DL and can be viewed as an expressive fragment of def-Horn. The paper emphasizes the importance of DLP-fusion for enabling interoperability between DL and LP, allowing for the use of efficient LP inferencing algorithms for reasoning over large-scale DL ontologies.