10 research outputs found

    DFKI publications : the first four years ; 1990 - 1993

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    Deductive Systems in Traditional and Modern Logic

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    The book provides a contemporary view on different aspects of the deductive systems in various types of logics including term logics, propositional logics, logics of refutation, non-Fregean logics, higher order logics and arithmetic

    Cooperative Situation Awareness in Transportation

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    Intelligent Transportation Systems (ITS) became a fast moving eld of research in the last decades, in particular in the context of continuously growing mobility and a high employment of resources starting from energy and material consumption to travel time and nally the human life. As it has already been experienced in other application areas, the introduction of communications technology is able to bring a revolutionary change in structures and behaviors long-believed to be carved in stone. The main idea behind this thesis is the usage of information not as a mere placeholder, e.g. a eld in a static message, but actively utilizing its content and dependencies. This requires an estimation of the actual worth of a single piece of information for the entity itself and the entities which are in communication range. This worth has to be the essential driver for the cooperative situation estimation. The active utilization of information and its cooperative dissemination provides the entities the opportunity to become situation aware and detect hazardous or inefficient situations early in advance. Since information always has a degree of uncertainty which is inherent to information in the real-world problem domain, as we are confronted with in ITS, probabilistic methods will be applied to model situation-relevant information. Conditional probability distributions in state transition models make for the evolvement of the situational information with the progress of time and handle causal dependencies between situational information. Together with a utility-based decision-making process dynamic probabilistic causal decision networks provide the functionality to select optimal actions given sequences of inaccurate and incomplete evidences. This thesis provides concepts and strategies that push forward the exploitation of information in a cooperative way within a probabilistic framework that allows to make various kinds of decisions with maximum utility. For the evaluation of the proposed concepts, the exemplary application Cooperative Adaptive Cruise Control (CACC) has been implemented on the basis of a particle lter which is used for the situation estimation. Initial simulations provided promising results and hence constitute a solid basis for future work in the eld of Cooperative Situation Awareness in Transportation

    DFKI publications : the first four years ; 1990 - 1993

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    Wissenschaftlich-Technischer Jahresbericht 1992

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    General default logic

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    In this paper, we propose a new nonmonotonic logic called general default logic. On the one hand, it generalizes Reiter’s default logic by adding to it rule-like operators used in logic programming. On the other hand, it extends logic programming by allowing arbitrary propositional formulas. We show that with this new logic, one can formalize naturally rule constraints, generalized closed world assumptions, and conditional defaults. We show that under a notion of strong equivalence, sentences of this new logic can be converted to a normal form. We also investigate the computational complexity of various reasoning tasks in the logic, and relate it to some other nonmonotonic formalisms such as Lin and Shoham’s logic of GK and Moore’s autoepistemic logic

    How to Prefer More Specific Defaults in Terminological Default Logic

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    In a recent paper we have proposed terminological default logic as a formalism which combines both means for structured representation of classes and objects, and for default inheritance of properties. The major drawback which terminological default logic inherits from general default logic is that it does not take precedence of more specific defaults over more general ones into account. This behaviour has already been criticized in the general context of default logic, but it is all the more problematic in the terminological case where the emphasis lies on the hierarchical organization of concepts. The present paper addresses the problem of modifying terminological default logic such that more specific defaults are preferred. It turns out that the existing approaches for expressing priorities between defaults do not seem to be appropriate for this purpose. Therefore we shall consider an alternative approach for dealing with prioritization in the framework of Reiter's def..
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