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The distributed ontology, modeling and specification language -- DOL
, 2013
"... There is a diversity of ontology languages in use, among them OWL, RDF, OBO, Common Logic, and F-logic. Related languages such as UML class diagrams, entity-relationship diagrams and object role modelling provide bridges from ontology modelling to applications, e.g. in software engineering and datab ..."
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Cited by 7 (4 self)
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There is a diversity of ontology languages in use, among them OWL, RDF, OBO, Common Logic, and F-logic. Related languages such as UML class diagrams, entity-relationship diagrams and object role modelling provide bridges from ontology modelling to applications, e.g. in software engineering and databases. Another diversity appears at the level of ontology modularity and relations among ontologies. There is ontology matching and alignment, module extraction, interpolation, ontologies linked by bridges, interpretation and refinement, and combination of ontologies. The Distributed Ontology, Modelling and Specification Language (DOL) aims at providing a unified meta language for handling this diversity. In particular, DOL provides constructs for (1) “as-is ” use of ontologies formulated in a specific ontology language, (2) ontologies formalised in heterogeneous logics, (3) modular ontologies, and (4) links between ontologies. This paper sketches the design of the DOL language. DOL will be submitted as a proposal within the OntoIOp (Ontology Integration and Interoperability) standardisation activity of the Object Management Group (OMG).
Forgetting for Answer Set Programs Revisited
- PROCEEDINGS OF THE TWENTY-THIRD INTERNATIONAL JOINT CONFERENCE ON ARTIFICIAL INTELLIGENCE
"... A new semantic forgetting for answer set programs (ASP), called SM-forgetting, is proposed in the paper. It distinguishes itself from the others in that it preserves not only skeptical and credulous consequences on unforgotten variables, but also strong equivalence – forgetting same variables in str ..."
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Cited by 3 (3 self)
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A new semantic forgetting for answer set programs (ASP), called SM-forgetting, is proposed in the paper. It distinguishes itself from the others in that it preserves not only skeptical and credulous consequences on unforgotten variables, but also strong equivalence – forgetting same variables in strongly equivalent logic programs has strongly equivalent results. The forgetting presents a positive answer to Gabbay, Pearce and Valverde’s open question – if ASP has uniform interpolation property. We also investigate some properties, algorithm and computational complexities for the forgetting. It shows that computing the forgetting result is generally intractable even for Horn logic programs.
Forgetting Concept and Role Symbols in ALCH-Ontologies
"... Abstract. We develop a resolution-based method for forgetting concept and role symbols in ALCH ontologies, or for computing uniform interpolants in ALCH. Uniform interpolants use only a restricted set of symbols, while preserving logical consequences of the original ontology involving these symbols. ..."
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Cited by 2 (1 self)
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Abstract. We develop a resolution-based method for forgetting concept and role symbols in ALCH ontologies, or for computing uniform interpolants in ALCH. Uniform interpolants use only a restricted set of symbols, while preserving logical consequences of the original ontology involving these symbols. While recent work towards practical methods for uniform interpolation in expressive description logics limits attention to forgetting concept symbols, we believe most applications would benefit from the possibility to forget both role and concept symbols. We focus on the description logic ALCH, which allows for the formalisation of role hierarchies. Our approach is based on a recently developed resolutionbased calculus for forgetting concept symbols in ALC ontologies, which we extend by redundancy elimination techniques to make it practical for larger ontologies. Experiments on ALCH fragments of real life ontologies suggest that our method is applicable in a lot of real-life applications. 1
Knowledge forgetting in circumscription: A preliminary report
- In Bonet and Koenig
"... The theory of (variable) forgetting has received signif-icant attention in nonmonotonic reasoning, especially, in answer set programming. However, the problem of establishing a theory of forgetting for some expressive nonmonotonic logics such as McCarthy’s circumscrip-tion is rarely explored. In thi ..."
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Cited by 1 (1 self)
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The theory of (variable) forgetting has received signif-icant attention in nonmonotonic reasoning, especially, in answer set programming. However, the problem of establishing a theory of forgetting for some expressive nonmonotonic logics such as McCarthy’s circumscrip-tion is rarely explored. In this paper a theory of for-getting for propositional circumscription is proposed, which is not a straightforward adaption of existing ap-proaches. In particular, some properties that are essen-tial for existing proposals do not hold any longer or have to be reformulated. Several useful properties of the new forgetting are proved, which demonstrate suitability of the forgetting for circumscription. A sound and com-plete algorithm for the forgetting is developed and an analysis of computational complexity is given.
K.: Forgetting under the well-founded semantics
- Logic Programming and Nonmonotonic Reasoning, 12th International Conference, LPNMR 2013, Corunna
"... Abstract. In this paper, we develop a notion of forgetting for normal logic programs under the well-founded semantics. We show that a num-ber of desirable properties are satisfied by our approach. Three different algorithms are presented that maintain the computational complexity of the well-founded ..."
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Cited by 1 (1 self)
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Abstract. In this paper, we develop a notion of forgetting for normal logic programs under the well-founded semantics. We show that a num-ber of desirable properties are satisfied by our approach. Three different algorithms are presented that maintain the computational complexity of the well-founded semantics, while partly keeping its syntactical structure. 1
On Forgetting Postulates in Answer Set Programming
"... Forgetting is an important mechanism for logic-based agent systems. A recent interest has been in the desirable properties of forgetting in answer set programming (ASP) and their impact on the design of forgetting operators. It is known that some sub-sets of these properties are incompatible, i.e., ..."
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Forgetting is an important mechanism for logic-based agent systems. A recent interest has been in the desirable properties of forgetting in answer set programming (ASP) and their impact on the design of forgetting operators. It is known that some sub-sets of these properties are incompatible, i.e., they cannot be satisfied at the same time. In this paper, we are interested in the question on the largest set ∆ of pairs (Π, V), where Π is a logic program and V is a set of atoms, such that a forgetting operator ex-ists that satisfies all the desirable properties for each (Π, V) in ∆. We answer this question positively by discovering the precise condition under which the knowledge forgetting, a well-established approach to forgetting in ASP, satisfies the property of strong persistence, which leads to a sufficient and neces-sary condition for a forgetting operator to satisfy all the desirable properties proposed in the literature. We explore computational complexities on check-ing the condition and present a syntactic character-ization which can serve as the basis of computing knowledge forgetting in ASP.
Games for Query Inseparability of Description Logic Knowledge Bases
"... We consider conjunctive query inseparability of description logic knowledge bases with respect to a given signature— a fundamental problem in knowledge base versioning, module extraction, forgetting and knowledge exchange. We give a uniform game-theoretic characterisation of knowledge base conjuncti ..."
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We consider conjunctive query inseparability of description logic knowledge bases with respect to a given signature— a fundamental problem in knowledge base versioning, module extraction, forgetting and knowledge exchange. We give a uniform game-theoretic characterisation of knowledge base conjunctive query inseparability and develop worst-case optimal decision algorithms for fragments of Horn-ALCHI, including the description logics underpinning OWL2QL and OWL2EL. We also determine the data and combined complexity of deciding query inseparabil-ity. While query inseparability for all of these logics is P-complete for data complexity, the combined complexity ranges from P- to ExpTime- to 2ExpTime-completeness. We use these results to resolve two major open problems for OWL2QL by showing that TBox query inseparability and the membership problem for universal conjunctive query solutions in knowledge exchange are both ExpTime-complete for combined complexity. Finally, we introduce a more flexible notion of inseparability which compares answers to conjunctive queries in a given signature over a given set of individuals. In this case, checking query inseparability becomes NP-complete for data complexity, but the ExpTime-and 2ExpTime-completeness combined complexity results are preserved.
When Are Description Logic Knowledge Bases Indistinguishable?∗
"... Deciding inseparability of description logic knowl-edge bases (KBs) with respect to conjunctive queries is fundamental for many KB engineering and maintenance tasks including versioning, mod-ule extraction, knowledge exchange and forget-ting. We study the combined and data complex-ity of this insepa ..."
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Deciding inseparability of description logic knowl-edge bases (KBs) with respect to conjunctive queries is fundamental for many KB engineering and maintenance tasks including versioning, mod-ule extraction, knowledge exchange and forget-ting. We study the combined and data complex-ity of this inseparability problem for fragments of Horn-ALCHI, including the description logics un-derpinning OWL 2 QL and OWL 2 EL.
Model-Theoretic Inseparability and Modularity of Description Logic Ontologies
"... The aim of this paper is to introduce and study model-theoretic notions of modularity in description logic and related reasoning problems. Our ap-proach is based on a generalisation of logical equivalence that is called model-theoretic inseparability. Two TBoxes are inseparable w.r.t. a vocabulary Σ ..."
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The aim of this paper is to introduce and study model-theoretic notions of modularity in description logic and related reasoning problems. Our ap-proach is based on a generalisation of logical equivalence that is called model-theoretic inseparability. Two TBoxes are inseparable w.r.t. a vocabulary Σ if they cannot be distinguished by the Σ-reducts of their models and thus can equivalently be replaced by one another in any application where only vocabulary items from Σ are relevant. We study in-depth the complexity of deciding inseparability for the description logics EL and ALC and their extensions with inverse roles. We then discuss notions of modules of a TBox based on model-theoretic inseparability and develop algorithms for extracting minimal modules from acyclic TBoxes. Finally, we provide an experimen-tal evaluation of our module extraction algorithm based on the large-scale medical TBox Snomed ct. 1.
