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Access control is an important issue related to the security on the Semantic Web. Role-Based Access Control (RBAC) is commonly considered as a flexible and efficient model in practice. In this paper, we provide an OWL-based approach for RBAC in the Semantic Web context. First we present an extended model of RBAC with negative authorization, providing detailed analysis of conflicts. Then we use OWL to formalize the extended model. Additionally, we show how to use an OWL-DL reasoner to detect the potential conflicts in the extended model.

Web ontology language OWL DL has two-valued model theory semantics so that ontologies expressed by it become trivial when contradictions occur. Based on classical description logic $\mathcal{SHOIN(D)}$, we propose the four-valued description logic $\mathcal{SHOIN(D)}{\it 4}$ which has the ability to reason with inconsistencies. By transformation technic, we convert the reasoning problems of $\mathcal{SHOIN(D)}{\it 4}$ to the counterparts of $\mathcal{SHOIN(D)}$. So $\mathcal{SHOIN(D)}{\it 4}$ provides us with an approach to deal with contradictions by classical reasoning mechanism.

Most techniques for probabilistic reasoning focus on reasoning about conditional probability constraints. However, human experts are accustomed to representing uncertain knowledge in the form of expectation rather than probability distribution directly in many cases. It is necessary to provide a logic for encoding hybrid probabilistic knowledge bases that contain expectation knowledge as well as the purely probabilistic knowledge in the form of conditional probability. This paper constructs a nonmonotonic logic for reasoning about hybrid probabilistic knowledge bases. We extend the propositional logic for reasoning about expectation to encoding hybrid probabilistic knowledge by introducing the conditional expectation constraint formula. Then we provide an approach to nonmonotonic reasoning about hybrid probabilistic knowledge bases. Finally, we compare this logic with related works.

In enterprise environment, security becomes increasingly important and costly. Enterprises are struggling to protect the increasing amount of disparate resources. Simple patchwork of security controls no longer suffices. Enterprises require a comprehensive solution that provides centralized security management, from authentication, to authorization and to auditing. To this end, we present a design and implementation of an integrative security management solution for Web-based enterprise applications, WebDaemon. It provides Single Sign-On to multiple Web applications. It also provides restricted access to Web-based content, portals, and Web applications based on Role-Based Access Control (RBAC) policies. The WebDaemon can help enterprises secure all Web resources with consistency of policy management and reduced administrative costs.

QAP is a famous $\mathcal{NP}-$Hard [1] combinatorial optimization problem. Many theoretical and real-life problems could be modeled as it. VNS is a recent metaheuristic and shows good performance in dealing with QAP [2]. In this paper, a new concept distance called permutation distance is proposed and exploited in detail. With permutation distance ready, we combine the hamming distance with it and propose a group of new neighborhood structures in QAP for VNS. Numerical tests running on the standard benchmark library QAPLIB [3] show that this approach would dramatically improve the performance of VNS for QAP. It surpasses some famous metaheuristics and belongs to the most efficient metaheuristics for QAP.

In this paper, a logical model for reasoning about rational agent's three attitudes Belief, Capability and Promise, incorporating the temporal aspect, is proposed. Diverse axioms that can reflect different properties of the agents are presented in a precise way by appropriate conditions according to the accessibility relations of the models. The inter-relations among the operators are also explored to characterize the interactions and cooperations between the agents. An illustrative reasoning example in the trading agent competition for supply chain management(TAC SCM) is presented to show the potential applications of the model.

Role-based access control (RBAC) is recognized as an excellent model for access control in large-scale networked applications. Formalization of RBAC in a logical approach makes it feasible to reason about a specified policy and verify its correctness. We propose a formalization of RBAC by the description logic language $\mathcal{ALCQ}$. We also show that the RBAC constraints can be captured by $\mathcal{ALCQ}$. Furthermore, we demonstrate how to make access control decision, perform the RBAC functions as well as check the consistency of RBAC via the description logic reasoner RACER.

The problem that “XML formally governs syntax only – not semantics” has been a serious barrier for XML-based data integration and the extension of current Web to Semantic Web. To address this problem, we propose the XML Semantics Definition Language(XSDL) to express XML author's intended meaning and propose a model-theoretic semantics for XML. Consequently, XML becomes a sub-language of RDF in expressiveness and XML data can be semantics-preserving transformed into RDF data. We further discuss the semantic entailment and validity of the XML documents.

The wide scale usage of OWL for the formalization of real-world ontologies is currently influenced by important limitations which concern both its expressivity and the efficiency of OWL specific reasoning tools. While the expressivity limitations may be overcame by extending the OWL language (e.g. with rules), the reasoning with such heterogeneous knowledge bases is still an open issue. In this paper we propose OWL2Jess, a prototypical tool which enables the transformation of OWL ontologies to Jess rule bases and thus enables OWL models to be extended by means of rules. Facts are derived from an initial OWL file by one XSLT stylesheet, while the RDF(S) and OWL Semantics are pre-defined as Jess rules. By making hidden knowledge explicit, OWL2Jess achieves the knowledge compilation: the implicit subsumption and membership relations can be subsequently identified using the Jess rule engine.

The three-valued formulation of nonmonotonic logics is established. It is shown how to extend standard nonmonotonic logics to the three-valued case. It is also shown that a three-valued nonmonotonic logic called maximally ignorant (MI) logic can capture various major standard nonmonotonic logics as its special cases. It is argued that the three-valued nonmonotonic logic is closely related to modal logic. >

It has been well recognized that common-sense reasoning is nonmonotonic. Nonmonotonic reasoning is prototypically described by the reasoning about normality and exception. In this paper, we firstly propose a modal logic about normality and exception. We then present a nonmonotonic modal logic which formalizes the intuitions of nonmonotonic reasoning directly, rather than go around to indirect criterion. The results can be seen by comparing our logic with major nonmonotonic logics in recent literature. In particular, we provide a first-order extension of default logic and autoepistemic logic, and the capability of circumscription to infer universal statement. As a result, the relations among various existing nonmonotonic logics coincide in our logic. >

In this paper we describe paraconsistent circumscription by application of predicate circumscription in a paraconsistent logic. In addition to circumscribe the predicates, we also circumscribe the inconsistency. Paraconsistent circumscription can be well characterized by the minimal semantics that is both nonmonotonic and paraconsistent. It brings us advantages at least in two respects: nonmonotonic logic would be nontrivial while there was a contradiction, and paraconsistent logic would be equivalent to classical logic while there was no direct effect of a contradiction.

G. Priest introduced nonmonotonicity into a paraconsistent logic, so-called logic of paradox LP, that yields a solution to the weakness of paraconsistent logic. The resulting logic (of minimal parades) LP/sub m/ is nonmonotonic in the sense that inconsistency is minimal. The problem of proof theory of logic LP/sub m/ left open because the base logic LP is paraconsistent so that syntactic formulations of nonmonotonic logic are not available for LP/sub m/, though LP/sub m/ is well characterized by minimal semantics. In this paper, we provide a minimal tableaus as a satisfactory proof theory for LP/sub m/. We first present a signed tableaux for LP. Then minimal tableaux for LP/sub m/ is obtained by revising signed tableaux for LP to fit LP/sub m/ in which the branches of non-minimally-inconsistent models of the tableaux are eliminated. The soundness and completeness theorems of the tableaux with respect to the semantics of LP and LP/sub m/ are proved, respectively.