We describe the design, implementation, and performance of a new system for access control on the web. To achieve greater flexibility in forming access-control policies – in particular, to allow better interoperabili...
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作者：
Gupta, GopalPontelli, EnricoApplied Logic
Programming Languages and Systems Lab. Department of Computer Science University of Texas at Dallas Richardson TX 95083 United States Laboratory for Logic
Databases and Advanced Programming Department of Computer Science New Mexico State University Las Cruces NM 88003 United States
Domain Specific Languages (DSLs) are high level languages designed for solving problems in a particular domain, and have been suggested as means for developing reliable software systems. We present a (constraint) logi...
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The shortest-paths problem is an important problem in graph theory and finds diverse applications in various fields. This is why shortest path algorithms have been designed more thoroughly than any other algorithm in ...
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The shortest-paths problem is an important problem in graph theory and finds diverse applications in various fields. This is why shortest path algorithms have been designed more thoroughly than any other algorithm in graph theory. A large number of optimization problems are mathematically equivalent to the problem of finding shortest paths in a graph. The Shortest-path between a pair of vertices is defined as the path with shortest length between the pair of vertices. The shortest path from one node to another often gives the best way to route message between the nodes. This paper presents an O(n 2 ) time algorithm for solving all pairs shortest path problems on trapezoid graphs which are extensions of interval graphs and permutation graphs. The space complexity of this algorithm is of O(n 2 ). This problem has been solved by constructing n breadth-first search (BFS) trees with each of the n vertices as root. As the lower bound of time complexity for computing the all pairs shortest paths is known to be of O(n 2 ), this proposed algorithm is optimal.
Modelica is a general equation-based object-oriented language for continuous and discrete-event modeling of physical systems for the purpose of efficient simulation. The language unifies and generalizes previous objec...
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Modelica is a general equation-based object-oriented language for continuous and discrete-event modeling of physical systems for the purpose of efficient simulation. The language unifies and generalizes previous object-oriented modeling languages. It is bringing about a revolution in this area, based on its ease of use, visual design of models with combination of Lego-like predefined model building blocks, its ability to define model libraries with re-usable components and its support for modeling and simulation of complex applications involving parts from several application domains. In this paper we present the Modelica language with emphasis on its language features and one of the associated simulation environments. Simulation models can be developed in an integrated problem-solving environment by using a graphical editor for connection diagrams. Connections are established just by drawing lines between objects picked from a class library. The principles of object oriented physical systems modeling and the multi-domain capabilities of the language are presented in the paper by several examples.
QoS solutions for Core Internet Networks require that we pay special attention to scalability, as they deal with a lot of flows and demand many resources. In this paper, integrated solutions from the physical layer (S...
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QoS solutions for Core Internet Networks require that we pay special attention to scalability, as they deal with a lot of flows and demand many resources. In this paper, integrated solutions from the physical layer (SDH/SONET and DTM) to the IP layer (IntServ and DiffServ) are analysed and proposed, concentrating not only on scalability, but also on QoS guarantees.
In this paper, the performance of turbo coded signals are investigated over Wireless Local Loop (WLL) environment with no side information on the phase noise and no channel state information (CSI). We assume that the ...
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In this paper, the performance of turbo coded signals are investigated over Wireless Local Loop (WLL) environment with no side information on the phase noise and no channel state information (CSI). We assume that the transmitter and the receiver are point-to-point microwave links, separated by WLL which is modelled as 1+Dn/Partial Response Microwave Channel (PMRC) with realizable and practical medium parameters. Here, the combined effects of the nonideal coherent receiver on the phase of the received amplitude and of a noisy carrier reference are considered, each modelled by the Rayleigh and Tikhonov distributions respectively. As an example, the jitter performance of turbo coded signals are evaluated over 1+D/PRMC with effective signal-to-noise ratio in the carrier tracking loop, fading parameter, iteration number and frame data block size. The numerical results clearly demonstrate the error performance degradation due to both amplitude fading and phase noise process.
If the distance between two vertices becomes longer after the removal of a vertex u, then u is called a hinge vertex. In this paper, a linear time sequential algorithm is presented to find all hinge vertices of an int...
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In this paper we study the use of parallelism to speed up execution of Answer Set Programs (ASP). ASP is an emerging programming paradigm which combines features from constraint programming, logic programming, and non...
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This paper introduces a calculus of weakest specification for supporting reuse of established components in deriving a design (in the sense of formal methods). The weakest specifunction generalizes the notions of weak...
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This paper introduces a calculus of weakest specification for supporting reuse of established components in deriving a design (in the sense of formal methods). The weakest specifunction generalizes the notions of weakest pre-specification and weakest parallel environment;but instead of calculating the weakest required component of a target specification, it calculates the weakest specification function whose value refines the target when applied to an established component. In particular it overcomes the restriction of those other calculi to taking merely one required component at a time. The theory of specifunctions is applied to a new weakest-design calculus in the context of BSP. The calculus is based on the par-seq specifunction which involves two required components: it places one established component in parallel with one required component and the result in sequence with another required component to meet a given specification. A calculus is provided for the par-seq specifunction and it is applied to the derivation of a distributed BSP algorithm for greatest common divisor.
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