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  1. On Specificity in Default Logic

    Jussi Rintanen
    The applicability of lexicographic comparison in nonmonotonic reasoning with specificity is investigated. A priority mechanism based on lexicographic comparison is defined for Reiter's default logic. The following principle earlier used by Geffner and Pearl in conditional entailment is used as the basis for specificity-based priorities for normal default theories: for each rule there is a context where it may not be defeated by any other rule. A method for computing priorities according to the principle is given. Connection to earlier work is discussed.

  2. The Problem Of Context From The Standpoint Of Artificial Intelligence

    Paolo Bouquet
    The notion of context has been called to account for a wide range of linguistic and cognitive phenomena, some of which are relevant also from an AI perspective. However, the notion of context that emerges from the works in philosophy of language and logic seems to be inadequate for AI, because it presupposes some assumptions that are untenable from a methodological point of view. In the paper, I propose a change of perspective which is motivated by the work on context in AI. Instead of a way for structuring a description, either partial or complete, of the world, contexts are...

  3. From Discrete Duration Calculus to Symbolic Automata

    Laure Gonnord; Nicolas Halbwachs; Pascal Raymond
    The goal of this paper is to translate (fragments of) the quantified discrete duration calculus QDDC, proposed by P. Pandya, into symbolic acceptors with counters. Acceptors are written in the synchronous programming language Lustre, in order to allow available symbolic verification tools (model-checkers, abstract interpreters) to be applied to properties expressed in QDDC. We show that important constructs of QDDC need non-deterministic acceptors, in order to be translated with a bounded number of counters, and an expressive fragment of the logic is identified and translated. Then, we consider a more restricted fragment, which only needs deterministic acceptors.

  4. Aggregate Functions in DLV

    Tina Dell'Armi; Wolfgang Faber; Giuseppe Ielpa; Nicola Leone; Gerald Pfeifer
    Disjunctive Logic Programming (DLP) is a very expressive formalism: it allows for expressing every property of finite structures that is decidable in the complexity class 6790-40260 . Despite this high expressiveness, there are some simple properties, often arising in real-world applications, which cannot be encoded in a simple and natural manner. Especially properties that require the use of arithmetic operators (like sum, count, or min) on a set of elements satisfying some conditions, cannot be naturally expressed in classic DLP. To overcome this deficiency, we extend DLP by aggregate functions. In contrast to a previous proposal, we also consider...

  5. Efficient Decentralized Monitoring of Safety in Distributed Systems

    Koushik Sen; Abhay Vardhan; Gul Agha; Grigore Rosu
    We describe an efficient decentralized monitoring algorithm that monitors a distributed program's execution to check for violations of safety properties. The monitoring is based on formulae written in PT-DTL, a variant of past time linear temporal logic that we define. PT-DTL is suitable for expressing temporal properties of distributed systems. Specifically, the formulae of PT-DTL are relative to a particular process and are interpreted over a projection of the trace of global states that represents what that process is aware of. A formula relative to one process may refer to other processes' local states through remote expressions and remote formulae....

  6. Information Retrieval and Situation Theory

    T. W. C. Huibers; M. Lalmas; C. J. Van Rijsbergen
    In 1986, Van Rijsbergen suggested a model of an information retrieval system based on logic. We have advocated in earlier work that a logical approach should be based on a theory of information, Situation Theory, which provides a powerful range of concepts, and is useful for modelling documents and queries for the purpose of information retrieval. We also showed that Situation Theory provides a framework to represent different types of information retrieval models, thus allowing speculation on their properties and their characterization language. This paper is an essay to convince the reader that Situation Theory presents many characteristics that are...

  7. The Design and Evaluation of a Defense System for Internet Worms

    Riccardo Scandariato; John Knight
    Many areas of society have become heavily dependent on services such as transportation facilities, utilities and so on that are implemented in part by large numbers of computers and communications links. Both past incidents and research studies show that a well-engineered Internet worm can disable such systems in a fairly simple way and, most notably, in a matter of a few minutes. This indicates the need for defenses against worms but their speed rules out the possibility of manually countering worm outbreaks. We present a platform that emulates the epidemic behavior of Internet active worms. For purposes of experimentation, the...

  8. Exploiting Paraphrases in a Question Answering System

    Fabio Rinaldi James; James Dowdall; Kaarel Kaljur; Michael Hess
    We present a Question Answering system for technical domains which makes an intelligent use of paraphrases to increase the likelihood of finding the answer to the user's question. The system implements a simple and e#cient logic representation of questions and answers that maps paraphrases to the same underlying semantic representation.

  9. Deciding Provability of Linear Logic Formulas

    Patrick Lincoln
    Introduction There are many interesting fragments of linear logic worthy of study in their own right, most described by the connectives which they employ. Full linear logic includes all the logical connectives, which come in three dual pairs: the exponentials ! and ?, the additives & and \Phi, and the multiplicatives\Omega and . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ....

  10. A Simple Gradient Sign Algorithm for Transmit Antenna Weight Adaptation with Feedback

    Brian C.Banister; James R. Zeidler; Member Ieee James R. Zeidler; Fellow Ieee
    In this paper a simple algorithm for adaptation of the complex baseband weights of a transmit antenna array using feedback from the receiver is proposed and analyzed. The system utilizes stochastic gradient adaptation to maximize the power delivered to the receiver for a constrained transmission power, which provides both fading diversity and beam steering gain. Dual perturbed transmission weight vectors are time multiplexed onto the pilot signal, and the receiver generates feedback selecting the perturbed weight vector which delivers greater power. This feedback is used to provide weight adaptation at the transmitter, and this adaptation is shown to be an...

  11. An Architecture for Retargeting Application Logic to Multiple Component

    Marselina Wiharto; Peter Stanski
    In this position paper, we present an abstraction framework that supports seamless migration of application logic between programming languages. It promotes the longevity of business rules and permits retargeting of these functions into numerous physical object oriented programming languages. We further demonstrate the framework through its ability to construct console and XML Web Service applications from a single language-neutral XML form.

  12. Balancing Design Options with Sherpa

    Timothy Sherwood; Mark Oskin; Brad Calder
    Application specific processors o#er the potential of rapidly designed logic specifically constructed to meet the performance and area demands of the task at hand. Recently, there have been several major projects that attempt to automate the process of transforming a predetermined processor configuration into a low level description for fabrication. These projects either leave the specification of the processor to the designer, which can be a significant engineering burden, or handle it in a fully automated fashion, which completely removes the designer from the loop.

  13. Building and Executing Proof Strategies in a Formal Metatheory

    Istituto Trentino Di Cultura; Alessandro Armando; Alessandro Armando; Alessandro Cimatti; Alessandro Cimatti
    This paper describes how "safe" proof strategies are represented and executed in the interactive theorem prover GETFOL. A formal metatheory (MT) describes and allows to reason about object level inference. A class of MT terms, called logic tactics, is used to represent proof strategies. The semantic attachment facility and the evaluation mechanism of the GETFOL system have been used to provide the procedural interpretation of logic tactics. The execution of logic tactics is then proved to be "safe" under the termination condition. The implementation within the GETFOL system is described and the synthesis of a logic tactic implementing a normalizer...

  14. Binary Cyclic Difference Set Codes Derived from Idempotents Based on Cyclotomic Cosets

    Martin Tomlinson; Cen Jung Tjhai; Marcel A. Ambroze; Mohammed Z. Ahmed
    It is shown that cyclic difference set codes and one-step majority-logic codes may be constructed from idempotents based upon the cyclomic cosets. The construction method produces the well known perfect difference set codes of lengths 21, 73, 273 and 1057 plus some new codes. The code design produces the dual code idempotent and following F. J. MacWilliams [1][2] [3], it is shown that this may be used directly to define the parity check matrix of the code. A feature of the cyclotomic idempotent codes is the incremental approach to the sparseness of the parity check matrix and the property of...

  15. An Experiment in Using Inductive Logic Programming to Uncover Pointcuts

    Kris Gybels; Andy Kellens; Uncover Pointcuts
    The subject of this paper is the transformation from pre-AOP legacy software to aspect-oriented software. To factor out crosscutting concerns from such software we propose the use of techniques to automate the task of uncovering pointcuts. We discuss problems inherent in this task and propose the use of inductive reasoning techniques for the automation. We apply such a technique to one kind of aspects: unique methods which can be found in a standard Smalltalk image.

  16. Phase Transitions and Stochastic Local Search in k-Term DNF Learning

    Ulrich Rückert; Stefan Kramer; Luc De Raedt
    In the past decade, there has been a lot of interest in phase transitions within artificial intelligence, and more recently, in machine learning and inductive logic programming. We investigate phase transitions in learning k-term DNF boolean formulae, a practically relevant class of concepts. We do not only show that there exist phase transitions, but also characterize and locate these phase transitions using the parameters k, the number of positive and negative examples, and the number of boolean variables. Subsequently, we investigate stochastic local search (SLS) for k-term DNF learning. We compare several variants that first reduce k-term DNF to SAT...

  17. Application of the Fuzzy Min-Max Neural Network Classifier to Problems with Continuous and Discrete Attributes

    A. Likas; K. Blekas; A. Stafylopatis
    . The fuzzy min-max classification network constitutes a promisimg pattern recognition approach that is based on hyberbox fuzzy sets and can be incrementally trained requiring only one pass through the training set. The definition and operation of the model considers only attributes assuming continuous values. Therefore, the application of the fuzzy min-max network to a problem with continous and discrete attributes, requires the modification of its definition and operation in order to deal with the discrete dimensions. Experimental results using the modified model on a difficult pattern recognition problem establishes the strengths and weaknesses of the proposed approach. INTRODUCTION Fuzzy...

  18. Relational Grammars for Knowledge Representation

    Renate Schmidt Centre; Renate A. Schmidt
    This paper aims to enhance the practical applicability of relational grammars, which have been devised for the semantic analysis of natural language. We focus on their application in knowledge representation. In particular, we address how the representation problem for kl-one-based knowledge representation systems can be automatically solved with the help of relational grammars. New rules are presented for natural language formulations, like has sons and has at least two sons, commonly arising in application domains. For accommodating the latter kind of sentences we introduce a new class of so-called (concrete) graded Peirce algebras. A graded Peirce algebra is a Peirce...

  19. A Survey on Parallel Logic Simulation

    Gerd Meister
    Simulation of logic designs is a very important part of the VLSI-design process. The increasing size of the designs requires more efficient simulation strategies to accelerate the simulation process. Parallel logic simulation seems to be a promising approach in this direction. This paper describes the basic principles of parallel logic simulation, discusses different approaches, and surveys the research done in this field so far. 1 Introduction In recent years the increasing demand for fast development of integrated circuits has caused many studies in the field of design of microelectronics and hardware units. A particular problem arises from the exploding number...

  20. Features and Feature Interactions in Software Engineering Using Logic

    Ragnhild Van Der Straeten; Ragnhild Van; Der Straeten; Johan Brichau
    Feature interactions are common when composing a software unit out of several features. We report on two experimental approaches using logic to describe features and feature interactions. The first approach proposes description logic as a formalization of feature models which allow reasoning about features. In the second approach, a metalevel representation of the software is proposed to capture conditions on features. These conditions are written in terms of the software's implementation providing a uniform formalism that can be applied to any software unit.

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