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Efficient Query Answering for OWL 2
"... Abstract. The QL profile of OWL 2 has been designed so that it is possible to use database technology for query answering via query rewriting. We present a comparison of our resolution based rewriting algorithm with the standard algorithm proposed by Calvanese et al., implementing both and conductin ..."
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Cited by 37 (5 self)
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Abstract. The QL profile of OWL 2 has been designed so that it is possible to use database technology for query answering via query rewriting. We present a comparison of our resolution based rewriting algorithm with the standard algorithm proposed by Calvanese et al., implementing both and conducting an empirical evaluation using ontologies and queries derived from realistic applications. The results indicate that our algorithm produces significantly smaller rewritings in most cases, which could be important for practicality in realistic applications. 1
Decision procedures for algebraic data types with abstractions
 IN 37TH ACM SIGACTSIGPLAN SYMPOSIUM ON PRINCIPLES OF PROGRAMMING LANGUAGES (POPL), 2010. DECISION PROCEDURES FOR ORDERED COLLECTIONS 15 SHE75. SAHARON SHELAH. THE MONADIC THEORY OF ORDER. THA ANNALS OF MATHEMATICS OF MATHEMATICS
, 2010
"... We describe a family of decision procedures that extend the decision procedure for quantifierfree constraints on recursive algebraic data types (term algebras) to support recursive abstraction functions. Our abstraction functions are catamorphisms (term algebra homomorphisms) mapping algebraic data ..."
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Cited by 36 (15 self)
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We describe a family of decision procedures that extend the decision procedure for quantifierfree constraints on recursive algebraic data types (term algebras) to support recursive abstraction functions. Our abstraction functions are catamorphisms (term algebra homomorphisms) mapping algebraic data type values into values in other decidable theories (e.g. sets, multisets, lists, integers, booleans). Each instance of our decision procedure family is sound; we identify a widely applicable manytoone condition on abstraction functions that implies the completeness. Complete instances of our decision procedure include the following correctness statements: 1) a functional data structure implementation satisfies a recursively specified invariant, 2) such data structure conforms to a contract given in terms of sets, multisets, lists, sizes, or heights, 3) a transformation of a formula (or lambda term) abstract syntax tree changes the set of free variables in the specified way.
Computing Change and Specificity with Equational Logic Programs
"... this paper, we present an equational logic framework for objects, methods, inheritance and overriding of methods. Overriding is achieved via the concept of specificity, which states that more specific methods are preferred to less specific ones. Specificity is computed with the help of negation ..."
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Cited by 35 (28 self)
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this paper, we present an equational logic framework for objects, methods, inheritance and overriding of methods. Overriding is achieved via the concept of specificity, which states that more specific methods are preferred to less specific ones. Specificity is computed with the help of negation as failure. We specify equational logic programs and show that their completed versions behave as intended. Furthermore, we prove that SLDENFresolution is complete if the equational theory is finitary, the completed programs are consistent, and no derivation flounders or is infinite; and we give syntactic conditions which guarantee nonfloundering and finiteness. Finally, we discuss how the approach can be extended to reasoning about the past in the context of incompletely specified objects or situations. It will turn out that constructive negation is needed to solve these problems
A Comparison of Query Rewriting Techniques for DLLite
"... An incomplete database is defined by a set of constraints and a partial database instance [1]. Answering conjunctive queries over incomplete databases is an important computational task that lies at the core of many problems, such as information integration [12], data exchange [9], and data warehous ..."
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Cited by 32 (0 self)
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An incomplete database is defined by a set of constraints and a partial database instance [1]. Answering conjunctive queries over incomplete databases is an important computational task that lies at the core of many problems, such as information integration [12], data exchange [9], and data warehousing [17]. Given
Unification in the Description Logic EL
"... Abstract. The Description Logic EL has recently drawn considerable attention since, on the one hand, important inference problems such as the subsumption problem are polynomial. On the other hand, EL is used to define large biomedical ontologies. Unification in Description Logics has been proposed a ..."
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Cited by 31 (21 self)
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Abstract. The Description Logic EL has recently drawn considerable attention since, on the one hand, important inference problems such as the subsumption problem are polynomial. On the other hand, EL is used to define large biomedical ontologies. Unification in Description Logics has been proposed as a novel inference service that can, for example, be used to detect redundancies in ontologies. The main result of this paper is that unification in EL is decidable. More precisely, we show that ELunification is NPcomplete, and thus has the same complexity as ELmatching. 1
A General Framework for Hindley/Milner Type Systems with Constraints
, 2000
"... with constraints. The basic idea is to factor out the common core of previous extensions of the Hindley/Milner system. I present a Hindley/Milner system where the constraint part is a parameter. Speci c applications can be obtained by providing speci c constraint systems which capture the applicat ..."
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Cited by 31 (7 self)
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with constraints. The basic idea is to factor out the common core of previous extensions of the Hindley/Milner system. I present a Hindley/Milner system where the constraint part is a parameter. Speci c applications can be obtained by providing speci c constraint systems which capture the application in mind. For instance, the Hindley/Milner system can be recovered by instantiating the constraint part to the standard Herbrand constraint system. Type system instances of the general framework are sound if the underlying constraint system is sound. Furthermore, I give a generic type inference algorithm for the general framework, under sucient conditions on the speci c constraint system type inference yields principal types.
Induction and coinduction in sequent calculus
 Postproceedings of TYPES 2003, number 3085 in LNCS
, 2003
"... Abstract. Proof search has been used to specify a wide range of computation systems. In order to build a framework for reasoning about such specifications, we make use of a sequent calculus involving induction and coinduction. These proof principles are based on a proof theoretic (rather than sett ..."
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Cited by 28 (8 self)
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Abstract. Proof search has been used to specify a wide range of computation systems. In order to build a framework for reasoning about such specifications, we make use of a sequent calculus involving induction and coinduction. These proof principles are based on a proof theoretic (rather than settheoretic) notion of definition [13, 20, 25, 51]. Definitions are akin to (stratified) logic programs, where the left and right rules for defined atoms allow one to view theories as “closed ” or defining fixed points. The use of definitions makes it possible to reason intensionally about syntax, in particular enforcing free equality via unification. We add in a consistent way rules for pre and post fixed points, thus allowing the user to reason inductively and coinductively about properties of computational system making full use of higherorder abstract syntax. Consistency is guaranteed via cutelimination, where we give the first, to our knowledge, cutelimination procedure in the presence of general inductive and coinductive definitions. 1
Maudenpa: Cryptographic protocol analysis modulo equational properties
 of Lecture Notes in Computer Science
, 2007
"... Abstract. In this tutorial, we give an overview of the MaudeNRL Protocol Analyzer (MaudeNPA), a tool for the analysis of cryptographic protocols using functions that obey different equational theories. We show the reader how to use MaudeNPA, and how it works, and also give some of the theoretical ..."
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Cited by 28 (6 self)
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Abstract. In this tutorial, we give an overview of the MaudeNRL Protocol Analyzer (MaudeNPA), a tool for the analysis of cryptographic protocols using functions that obey different equational theories. We show the reader how to use MaudeNPA, and how it works, and also give some of the theoretical background behind the tool. 1
Experimental analysis of a webbased training intervention to develop positive psychological capital. Academy of Management Learning
 and Education
, 2008
"... Psychological capital with components of hope, selfefficacy, optimism, and resiliency has recently emerged as a core construct in taking positive psychology to the workplace. A distinguishing feature is that it is “statelike ” and thus open to development. We analyze whether such psychological cap ..."
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Cited by 28 (3 self)
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Psychological capital with components of hope, selfefficacy, optimism, and resiliency has recently emerged as a core construct in taking positive psychology to the workplace. A distinguishing feature is that it is “statelike ” and thus open to development. We analyze whether such psychological capital can be developed through a highly focused, 2hour webbased training intervention. Using a pretest, posttest experimental design (n 187 randomly assigned to the treatment group and n 177 to the control group), we found support that psychological capital can be developed by such a training intervention. Although the importance of positivity has been given attention through the years, only recently has it been proposed as a new (or at least renewed) lens to focus study on organizational behavior
Unification with Sequence Variables And Flexible Arity Symbols and its Extension with PatternTerms
 ARTIFICIAL INTELLIGENCE, AUTOMATED REASONING AND SYMBOLIC COMPUTATION. PROC. OF JOINT AISC’2002 – CALCULEMUS’2002 CONFERENCE, VOLUME 2385 OF LNAI
, 2002
"... A minimal and complete unification procedure for a theory with individual and sequence variables, free constants and free fixed and flexible arity function symbols is described and a brief overview of an extension with patternterms is given. ..."
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Cited by 27 (14 self)
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A minimal and complete unification procedure for a theory with individual and sequence variables, free constants and free fixed and flexible arity function symbols is described and a brief overview of an extension with patternterms is given.