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62
private communication
, 1996
"... Molecular cloning and expression analysis of a new gene for shortchain dehydrogenase/reductase 9 ..."
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Cited by 72 (2 self)
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Molecular cloning and expression analysis of a new gene for shortchain dehydrogenase/reductase 9
Can you tell the difference between DLLite ontologies
 IN PROCEEDINGS OF KR’08
, 2008
"... We develop a formal framework for comparing different versions of DLLite ontologies. Four notions of difference and entailment between ontologies are introduced and their applications in ontology development and maintenance discussed. These notions are obtained by distinguishing between differences ..."
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Cited by 50 (5 self)
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We develop a formal framework for comparing different versions of DLLite ontologies. Four notions of difference and entailment between ontologies are introduced and their applications in ontology development and maintenance discussed. These notions are obtained by distinguishing between differences that can be observed among concept inclusions, answers to queries over ABoxes, and by taking into account additional context ontologies. We compare these notions, study their metaproperties, and determine the computational complexity of the corresponding reasoning tasks. Moreover, we show that checking difference and entailment can be automated by means of encoding into QBF satisfiability and using offtheshelf QBF solvers. Finally, we explore the relationship between the notion of forgetting (or uniform interpolation) and our notions of difference between ontologies.
Referring expressions as formulas of description logic
 in: 5th Int. Nat. Lang. Generation Conf. Salt Fork
, 2008
"... In this paper, we propose to reinterpret the problem of generating referring expressions (GRE) as the problem of computing a formula in a description logic that is only satisfied by the referent. This view offers a new unifying perspective under which existing GRE algorithms can be compared. We also ..."
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Cited by 20 (4 self)
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In this paper, we propose to reinterpret the problem of generating referring expressions (GRE) as the problem of computing a formula in a description logic that is only satisfied by the referent. This view offers a new unifying perspective under which existing GRE algorithms can be compared. We also show that by applying existing algorithms for computing simulation classes in description logic, we can obtain extremely efficient algorithms for relational referring expressions without any danger of running into infinite regress. 1
Pure extensions, proof rules and hybrid axiomatics
 Preliminary proceedings of Advances in Modal Logic (AiML 2004
, 2004
"... We examine the role played by proof rules in general axiomatisations for hybrid logic. We prove three main results. First, all known axiomatisations for the basic hybrid language ..."
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Cited by 20 (6 self)
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We examine the role played by proof rules in general axiomatisations for hybrid logic. We prove three main results. First, all known axiomatisations for the basic hybrid language
Decomposing description logic ontologies
, 2010
"... Recent years have seen the advent of large and complex ontologies, most notably in the medical domain. As a consequence, structuring mechanisms for ontologies are nowadays viewed as an indispensible tool. A basic such mechanism is the automatic decomposition of the vocabulary of an ontology into ind ..."
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Cited by 17 (1 self)
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Recent years have seen the advent of large and complex ontologies, most notably in the medical domain. As a consequence, structuring mechanisms for ontologies are nowadays viewed as an indispensible tool. A basic such mechanism is the automatic decomposition of the vocabulary of an ontology into independent parts. In this paper, we study decompositions that are syntax independent in the sense that the resulting partitioning depends only on the meaning of the vocabulary items, but not on the concrete syntactic form of the axioms in the ontology. We present the first systematic investigation of decompositions of this type in the context of ontologies. Specifically, we focus on ontologies formulated in description logics and provide a variety of results that range from theorems stating the existence of unique finest decompositions to complexity results and algorithms computing decompositions. We also investigate the relationship between the existence of unique finite decompositions and a variant of the Craig interpolation property called parallel interpolation.
RelationshipBased Access Control: Its Expression and Enforcement Through Hybrid Logic
"... Access control policy is typically defined in terms of attributes, but in many applications it is more natural to define permissions in terms of relationships that resources, systems, and contexts may enjoy. The paradigm of relationshipbased access control has been proposed to address this issue, an ..."
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Access control policy is typically defined in terms of attributes, but in many applications it is more natural to define permissions in terms of relationships that resources, systems, and contexts may enjoy. The paradigm of relationshipbased access control has been proposed to address this issue, and modal logic has been used as a technical foundation. We argue here that hybrid logic – a natural and wellestablished extension of modal logic – addresses limitations in the ability of modal logic to express certain relationships. We identify a fragment of hybrid logic to be used for expressing relationshipbased accesscontrol policies, show that this fragment supports important policy idioms, and demonstrate that it removes an exponential penalty in existing attempts of specifying complex relationships such as “at least three friends ”. We also capture the previously studied notion of relational policies in a static type system.
Coalgebraic hybrid logic
 IN FOUNDATIONS OF SOFTWARE SCIENCE AND COMPUTATION STRUCTURES, FOSSACS 09, VOLUME 5504 OF LNCS
, 2009
"... We introduce a generic framework for hybrid logics, i.e. modal logics additionally featuring nominals and satisfaction operators, thus providing the necessary facilities for reasoning about individual states in a model. This framework, coalgebraic hybrid logic, works at the same level of generality ..."
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We introduce a generic framework for hybrid logics, i.e. modal logics additionally featuring nominals and satisfaction operators, thus providing the necessary facilities for reasoning about individual states in a model. This framework, coalgebraic hybrid logic, works at the same level of generality as coalgebraic modal logic, and in particular subsumes, besides normal hybrid logics such as hybrid K, a wide variety of logics with nonnormal modal operators such as probabilistic, graded, or coalitional modalities and nonmonotonic conditionals. We prove a generic finite model property and an ensuing weak completeness result, and we give a semantic criterion for decidability in PSPACE. Moreover, we present a fully internalised PSPACE tableau calculus. These generic results are easily instantiated to particular hybrid logics and thus yield a wide range of new results, including e.g. decidability in PSPACE of probabilistic and graded hybrid logics.
The Expressive Power of Memory Logics
, 2010
"... We investigate the expressive power of memory logics. These are modal logics extended with the possibility to store (or remove) the current node of evaluation in (or from) a memory, and to perform tests on the memory. In this context, the hybrid logic HL(↓) can be thought of as a particular case o ..."
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We investigate the expressive power of memory logics. These are modal logics extended with the possibility to store (or remove) the current node of evaluation in (or from) a memory, and to perform tests on the memory. In this context, the hybrid logic HL(↓) can be thought of as a particular case of a memory logic where the memory is an indexed list of elements of the domain. This work focuses in the case where the memory is a set, and we can test whether the current node belongs to the set. We prove that, in terms of expressive power, the memory logics we discuss here lie between the basic modal logic K and HL(↓). We show that the satisfiability problem of most of the logics we cover is undecidable. The only logic with a decidable satisfiability problem is obtained by imposing strong constraints on which elements can be memorized.
Completeness Results for Memory Logics
"... Abstract. Memory logics are a family of modal logics in which standard relational structures are augmented with data structures and additional operations to modify and query these structures. In this paper we present sound and complete axiomatizations for some members of this family. We analyze the ..."
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Abstract. Memory logics are a family of modal logics in which standard relational structures are augmented with data structures and additional operations to modify and query these structures. In this paper we present sound and complete axiomatizations for some members of this family. We analyze the use of nominals to achieve completeness, and present one example in which they can be avoided. 1 Modal Logics with Memory Many attempts have been made in recent years to increase modal logic expressivity by adding some notion of state to standard relational structures. This is a natural need, since modal logics are used in many different scenarios as tools for modeling behavior. One example of how this can be achieved comes from epistemic logic with dynamic operators, which allow to express the evolution of knowledge by knowledgechanging actions. Such logics are often called Dynamic Epistemic Logics (DEL) [16], and a large number of DELs has been proposed [9, 13–15]. These
RelationChanging Modal Operators
"... Abstract. We study dynamic modal operators that can change the accessibility relation of a model during the evaluation of a formula. In particular, we extend the basic modal language with modalities that are able to delete, add or swap an edge between pairs of elements of the domain. We define a g ..."
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Abstract. We study dynamic modal operators that can change the accessibility relation of a model during the evaluation of a formula. In particular, we extend the basic modal language with modalities that are able to delete, add or swap an edge between pairs of elements of the domain. We define a generic framework to characterize this kind of operations. First, we investigate relationchanging modal logics as fragments of classical logics. Then, we use the new framework to get a suitable notion of bisimulation for the logics introduced, and we investigate their expressive power. Finally, we show that the complexity of the model checking problem for the particular operators introduced is PSpacecomplete, and we study two subproblems of model checking: formula complexity and program complexity.