Mostrando recursos 281 - 300 de 188,281

  1. Abstract Robin Hood’s Algorithm for Time-Critical Level of Detail

    We describe a novel method for time-critical rendering of complex scenes populated by numerous distinct objects having an intricate geometry. During the preprocessing step the time consumed by logic and rendering processes is measured. For each frame we estimate the rendering time and distribute it between each potentially visible object which chooses its best representation within the time restrictions. Finally we take advantage of the unused time to improve the rendering process of the remaining objects. This method adjusts image quality adaptively and aims to maintain a constant bounded frame rate even for scenes which complexity may change drastically between...

  2. Formalizing Specifications for Geographic Information

    Jesper Vinther Christensen
    The presented work is a framework for developing production specifications for geographic information. The framework includes support for both natural language and formal language specifications, and what are important, mappings between statements in natural language and statements in formal language. The framework includes a build-in formal specification language, the High Level Constraint Language (HLCL), which is based on a first order predicate logic. HLCL can be regarded as a kind of description logic extended with some extra facilities, which makes it well suited for specifying complex rules and constraints that often occurs while specifying spatial properties. Further more HLCL is...

  3. 33.2 A Scan BIST Generation Method Using A Markov Source And Partial Bit-Fixing

    Irith Pomeranz
    Recently, Markov sources were shown to be effective in designing pseudo-random test pattern generators with low area overhead for built-in self-test of scan designs. This paper presents a new test pattern generation scheme based on a Markov source and a partial bit-fixing technique. A new method is proposed for the computation of the state transition probabilities of the Markov source based on the statistics of a deterministic test set. This is enhanced by partial bit-fixing logic, which fixes a group of consecutive inputs to all-0 or all-1. Experimental results show that the proposed BIST scheme can achieve 100 % fault...

  4. Linear logic as a framework for specifying sequent calculus

    Dale Miller; Elaine Pimentel
    Abstract. In recent years, intuitionistic logic and type systems have been used in numerous computational systems as frameworks for the specification of natural deduction proof systems. As we shall illustrate here, linear logic can be used similarly to specify the more general setting of sequent calculus proof systems. Linear logic’s meta theory can be used also to analyze properties of a specified object-level proof system. We shall present several example encodings of sequent calculus proof systems using the Forum presentation of linear logic. Since the object-level encodings result in logic programs (in the sense of Forum), various aspects of object-level...

  5. Conditional probabilistic reasoning without conditional logic

    Fabrizio Sebastiani
    Imaging is a class of non-Bayesian methods for the revision of probability density functions originally proposed as a semantics for conditional logic. Two of these revision functions, Standard Imaging and General Imaging, have successfully been applied to modelling information retrieval (IR). Due to the problematic nature of a“direct ” implementation of Imaging revision functions, we propose their alternative implementation by representing the semantic structure that underlies them, in the language of a probabilistic (Bayesian) logic. Recasting these models of information retrieval in such a general-purpose knowledge representation (KR) tool, besides showing the potential of this “Bayesian ” tool for the...

  6. A computational approach to pocklington certificates in type theory

    Benjamin Grégoire; Laurent Théry; Benjamin Werner
    Abstract. Pocklington certificates are known to provide short proofs of primality. We show how to perform this in the framework of formal, mechanically checked, proofs. We present an encoding of certificates for the proof system Coq which yields radically improved performances by relying heavily on computations inside and outside of the system (twolevel approach). 1 Formal Computational Proofs 1.1 Machines and the Quest for Correctness It is generally considered that modern mathematical logic was born towards the end of 19 th century, with the work of logicians like Frege, Peano, Russell or Zermelo, which lead to the precise definition of...

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    Virtual training environments require a flexible scenario creation system that can accommodate different training scenarios to address a wide range of situations for different levels of trainee expertise. Hence, the scenario logic or behaviour should not be hard-coded in the simulation engine and should be accessible to the trainer or domain expert. We present a rules acquisition tool called OntRAT that combines an ontology that represents and stores knowledge in a structured format and remains at a high-level of abstraction which is accessible by domain experts, and a set of rules that enables reasoning about the knowledge to solve problems....

  8. Generalized Kripke models for epistemic logic

    Frans Voorbraak
    In this paper a generalization of Kripke models is proposed for systemizing the study of the many different epistemic notions that appear in the literature. The generalized Kripke models explicitly represent an agent's epistemic states to which the epistemic notions refer. Two central epistemic notions are identified: objective (S5) knowledge and rational introspective (KD45) belief. Their interaction is determined and a notion of justified true belief is explained in terms of them. The logic of this notion of justified true belief is shown to be S4.2, which is in accordance with a conjecture by Wolfgang Lenzen. The logic of justified...

  9. FOCLASA 2005 Preliminary Version Designing a BPEL Orchestration Engine based on ReSpecT Tuple Centres

    Michele Cabano; Enrico Denti; Ro Ricci; Mirko Viroli
    We present the design of a BPEL orchestration engine based on ReSpecT tuple centres, a coordination model extending Linda with the ability of declaratively programming the reactive behaviour of tuple spaces. Architectural and linguistic aspects of our solution are discussed, focussing on how the syntax and semantics of BPEL have been mapped to tuple centres. This is achieved by a translation of BPEL specifications to set of logic tuples, and conceiving the execution cycle of the orchestration engine in terms of ReSpecT reactions. 1

  10. An Integration Tool for Life-Cycle Engineering

    Kathryn M. Chalfan
    Life-cycle engineering is the integration of the design process, which addresses primarily the system's performance, with analysis of the design's other attributes, including reliability, maintainability, lifecycle cost, and manufacturability. The advent of symbolic approaches to design integration reveals the requirement and opportunity of using higher-level analysis to select the optimum design. This opportunity is present only when human interaction is reduced sufficiently to permit several complete design and analysis cycles to take place. We have implemented a generic integration tool that has been demonstrated to significantly shorten the design cycle, and are studying its application to life-cycle engineering. This logic-based...

  11. Description logic reasoning using the pttp approach

    Zsolt Nagy; Gergely Lukácsy; Péter Szeredi
    The goal of this paper is to present how the Prolog Technology Theorem Proving (PTTP) approach can be used for ABox-reasoning. This work presents an inference algorithm over the language ALC, and evaluates its performance highlighting the advantages and drawbacks of this method. 1 Introduction and

  12. Static Analysis of Security Properties

    In Mobile Ambients; Chiara Braghin; Agostino Cortesi; Albert Einstein
    Security is a major concern for computation in wide-area networks, and is often considered a serious source of potential limitation to a widespread use of mobile code technologies. This key issue has stimulated the research on efficient validation and verification techniques ensuring the acceptable behaviour of software components roaming around on information networks. In this dissertation, we study the impact of an analysis methodology based on control flow analysis in flow logic style on the verification of information-flow security properties in the calculus of Mobile Ambients. The ambient calculus is a minimal formalism where the notion of ambient captures the...

  13. Composition of semantic web services using linear logic theorem proving

    Jinghai Rao; Peep Küngas; Mihhail Matskin
    This paper introduces a method for automatic composition of semantic web services using Linear Logic (LL) theorem proving. The method uses semantic web service language (DAML-S) for external presentation of web services, while, internally, the services are presented by extralogical axioms and proofs in LL. LL, as a resource conscious logic, enables us to define attributes of web services formally (including qualitative and quantitative values of non-functional attributes). The subtyping rules that are used for semantic reasoning are presented with LL inference figures. We propose a system architecture where the DAML-S Translator, LL Theorem Prover and Semantic Reasoner can operate...

  14. Limit of learning sequences with retractable guesses

    Stefano Berardi
    This is a contribution to constructive interpretation of classical logical proofs, that we see as learning strategies. We report on results about the limits of an abstract representation of learning processes, we call learning sequence, coming from Coquand’s game theoretic interpretation of classical logic. Inspired to Gold’s notion of limiting recursion and to the recent proposal of Limit-Computable Mathematics by Hayashi, we investigate the idea of learning in the limit in the general case, where both guess retraction and resumption are allowed. 1


    Jan Friso Groote; Olga Tveretina Binary decision diagrams for first-order predicate logic

  16. janvier 2006 – Journées Francophones des Langages Applicatifs – JFLA06 Erasure and Duplication in Classical Computation

    D. ˇ Zunić; P. Lescanne
    We present the *X-calculus, a linear model of computation, which has a direct Curry-Howard correspondence with classical logic. The logical setting is classical sequent calculus. *X introduces terms for explicit erasure and duplication, which correspond to weakening and contraction on the logical side. Furthermore, it is a calculus of explicit substitutions. Non-confluence and interface preservation are also some of the features. Since λ-calculus is easily represented, the untyped language is Turing-complete. 1.

  17. An accelerated Branch-and-Bound algorithm for assignment problems of utility systems

    Ros M. Strouvalis A; Istvan Heckl B; Ferenc Friedler B; Antonis C. Kokossis C
    A methodology is proposed for implementing logic and engineering knowledge within a Branch-and-Bound algorithm and with a purpose to accelerate convergence. The development addresses assignment problems of utility networks with an emphasis on the optimal allocation of units for maintenance problems. Proposed criteria are presented to automatically tailor the solution strategy and fully customise the optimisation solver. Model and problem properties are exploited to reduce the solution space, prioritise the branching of nodes, calculate lower bounds, and prune inferior parts of the binary tree. Comparisons with commercial MILP solvers demonstrate the significant merits of customising the solution search engine to...

  18. The theory of calculi with explicit substitutions revisited

    Delia Kesner
    Calculi with explicit substitutions (ES) are widely used in different areas of computer science. Complex systems with ES were developed these last 15 years to capture the good computational behaviour of the original systems (with meta-level substitutions) they were implementing. In this paper we first survey previous work in the domain by pointing out the motivations and challenges that guided the development of such calculi. Then we use very simple technology to establish a general theory of explicit substitutions for the lambda-calculus which enjoys fundamental properties such as simulation of one-step beta-reduction, confluence on metaterms, preservation of beta-strong normalisation, strong...

  19. Volatile FPGA design security – a survey

    Saar Drimer
    Volatile FPGAs, the dominant type of programmable logic devices, are used for space, military, automotive, and consumer electronics applications which require them to operate in a wide range of environments. Their continuous growth in both capability and capacity now requires significant resources to be invested in the designs that are created for them. This has brought increased interest in their security attributes; specifically, how well does the FPGA protect the information processed within it, how are FPGA designs protected during distribution, and how developers’ ownership rights are protected while designs from multiple sources are combined. This survey, which assumes very...

  20. Empirical Learning of Natural Language Processing Tasks

    Walter Daelemans; Antal Van Den Bosch; Ton Weijters
    Language learning has thus far not been a hot application for machine-learning (ML) research. This limited attention for work on empirical learning of language knowledge and behaviour from text and speech data seems unjusti ed. After all, it is becoming apparent that empirical learning of Natural Language Processing (NLP) can alleviate NLP's all-time main problem, viz. the knowledge acquisition bottleneck: empirical ML methods such as rule induction, top down induction of decision trees, lazy learning, inductive logic programming, and some types of neural network learning, seem to be excellently suited to automatically induce exactly that knowledge that is hard to...

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