We consider the problem of updating nonmonotonic knowledge bases represented by epistemic logic programs where disjunctive information and notions of knowledge and beliefs can be explicitly expressed. We propose a for...
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We consider the problem of updating nonmonotonic knowledge bases represented by epistemic logic programs where disjunctive information and notions of knowledge and beliefs can be explicitly expressed. We propose a formulation for epistemic logic program updates based on a principle called minimal change and maximal coherence. the central feature of our approach is that during an update procedure, contradictory information is removed on a basis of minimal change under the semantics of epistemic logic programs and then coherent information is maximally retained in the update result. By using our approach, we can characterize an update result in both semantic and syntactic forms. We show that our approach handles update sequences and satisfies the consistency requirement. We also investigate important semantic properties of our update approach such as reduction, persistence and preservation.
this paper introduces stratified programming, a novel approach for program construction. In essence, stratified programming allows the developer to build and execute software at various levels of abstraction, each lev...
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ISBN:
(纸本)1880843463
this paper introduces stratified programming, a novel approach for program construction. In essence, stratified programming allows the developer to build and execute software at various levels of abstraction, each level corresponding to a program stratum that provides a specific degree of functionality. Although there is a significant amount of work reported in the scientific literature on program refinement none of this work, to the best of our knowledge, has proposed mechanisms for switching the level of software details at the execution stage or suggested the use of program strata in a larger software engineering context. this not only makes the approach described in this paper highly innovative but also opens new related research and development directions across the entire software life-cycle. To illustrate the approach we present an example focused on the coding phase of the software process. Several avenues of further investigation are also indicated and the practical benefits of stratified programming are discussed in the context of modem software construction methodologies.
Health Care Computing and Communication Systems (HCCS) are characterized by the complexity of the organizations to take into account and the richness of properties that are required. To address this complexity and ric...
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ISBN:
(纸本)1402074492
Health Care Computing and Communication Systems (HCCS) are characterized by the complexity of the organizations to take into account and the richness of properties that are required. To address this complexity and richness, we propose a security policy based on roles, groups of objects and context. Indeed, similarly to roles that structure the subjects, we introduce the new concept "group of objects,, which structures objects. Our major aim is to facilitate the security policy management, to cope with access right complexity, and to reduce administration errors. then we develop a security model that covers the diversity of HCCS while achieving a good compromise between the respect of the least privilege principle and the flexibility of the access control. Following a logical approach, we design a formal system that extends the deontic logic, and we express the security policy in our language.
An agent communication protocol specifies the "rules of encounter" governing a dialogue between agents in a multiagent system. In non-cooperative interactions (such as negotiation dialogues) occurring in ope...
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An agent communication protocol specifies the "rules of encounter" governing a dialogue between agents in a multiagent system. In non-cooperative interactions (such as negotiation dialogues) occurring in open societies it is crucial that agents are equipped with proper means to check, and possibly enforce, conformance to protocols. We identify different levels of conformance (weak, exhaustive, and robust conformance) and explore how a specific class of logic-based agents can exploit a new representation formalism for communication protocols based on simple if-then rules in order to either check conformance a priori or enforce it at runtime.
Current Description logic reasoning systems provide only limited support for debugging logically erroneous knowledge bases. In this paper we propose new non-standard reasoning services which we designed and implemente...
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Current Description logic reasoning systems provide only limited support for debugging logically erroneous knowledge bases. In this paper we propose new non-standard reasoning services which we designed and implemented to pinpoint logical contradictions when developing the medical terminology DICE. We provide complete algorithms for unfoldable ACC-TBoxes based on minimisation of axioms using Boolean methods for minimal unsatisfiability-presening sub-TBoxes, and an incomplete bottom-up method for generalised incoherence-preserving terminologies. 'DICE stands for "Diagnoses for Intensive Care Evaluation". the development of the DICE terminology has been supported by the NICE foundation.
Computing least common subsumers (Ics) and most specific concepts (msc) are inference tasks that can support the bottom-up construction of knowledge bases in description logics. In description logics with existential ...
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Computing least common subsumers (Ics) and most specific concepts (msc) are inference tasks that can support the bottom-up construction of knowledge bases in description logics. In description logics with existential restrictions, the most specific concept need not exist if one restricts the attention to concept descriptions or acyclic TBoxes. In this paper, we extend the notions les and msc to cyclic TBoxes. For the description logic EC (which allows for conjunctions, existential restrictions, and the top-concept), we show that the les and msc always exist and can be computed in polynomial time if we interpret cyclic definitions with greatest fixpoint semantics.
We derive different views of an interactive double-ended bounded queue in the setting of stream processing functions. the views describe major abstraction levels relevant for the stepwise design of an implementation. ...
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ISBN:
(纸本)1880843463
We derive different views of an interactive double-ended bounded queue in the setting of stream processing functions. the views describe major abstraction levels relevant for the stepwise design of an implementation. the external view models the input/output behaviour, the internal view reflects a state-based description, the trace view presents an event-based characterization. the different views are systematically derived from the external view following sound transformation rules. the case study exemplifies formal methods for the systematic refinement of interactive components.
Fages showed that if a program is tight, then every propositional model of its completion is also its stable model. Recently, Babovich, Erdem, and Lifschitz generalized Fages' result, and showed that this is also ...
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Fages showed that if a program is tight, then every propositional model of its completion is also its stable model. Recently, Babovich, Erdem, and Lifschitz generalized Fages' result, and showed that this is also true if the program is tight on the given model of the completion. As it turned out, this is quite a general result. Among the commonly known benchmark domains, only Niemelii's normal logic program encoding of the Hamiltonian Circuit (HC) problem does not have this property. In this paper, we propose a new normal logic program for solving the HC problem, and show that the program is tight on every model of its completion. Experimental results showed that for many graphs, this new encoding improves the performance of both SMODELS and ASSAT(Chaff2), especially of the latter system which is based on the SAT solver Chaff2. We also propose a notion of inherently tight logic programs and show that for any program, it is inherently tight iff all its completion models are stable models. We then propose a polynomial transformation from a logic programs to one that is inherently tight, thus providing a reduction of stable model semantics to program completion semantics and SAT.
the computation of the first complete approximations of game-theoretic optimal strategies for full-scale poker is addressed. Several abstraction techniques are combined to represent the game of 2-player Texas Hold'...
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the computation of the first complete approximations of game-theoretic optimal strategies for full-scale poker is addressed. Several abstraction techniques are combined to represent the game of 2-player Texas Hold'em, having size O(1018), using closely related models each having size 0(1O 7). Despite the reduction in size by a factor of 100 billion, the resulting models retain the key properties and structure of the real game. Linear programming solutions to the abstracted game are used to create substantially improved poker-playing programs, able to defeat strong human players and be competitive against world-class opponents.
To model combinatorial decision problems involving uncertainty and probability, we extend the stochastic constraint programming framework proposed in iWalsh, 2002] along a number of important dimensions (e.g. to multi...
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To model combinatorial decision problems involving uncertainty and probability, we extend the stochastic constraint programming framework proposed in iWalsh, 2002] along a number of important dimensions (e.g. to multiple chance constraints and to a range of new objectives). We also provide a new (but equivalent) semantics based on scenarios. Using this semantics, we can compile stochastic constraint programs down into conventional (non-stochastic) constraint programs. this allows us to exploit the full power of existing constraint solvers. We have implemented this framework for decision making under uncertainty in stochastic OPL, a language which is based on the OPL constraint modelling language [Hentenryck et al., 1999]. To illustrate the potential of this framework, we model a wide range of problems in areas as diverse as finance, agriculture and production.
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