7 research outputs found

    PrIC3: Property Directed Reachability for MDPs

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    IC3 has been a leap forward in symbolic model checking. This paper proposes PrIC3 (pronounced pricy-three), a conservative extension of IC3 to symbolic model checking of MDPs. Our main focus is to develop the theory underlying PrIC3. Alongside, we present a first implementation of PrIC3 including the key ingredients from IC3 such as generalization, repushing, and propagation

    Influence of heat input on microstructure and toughness properties in simulated CGHAZ of X80 steel manufactured using high-temperature processing

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    To determine and demonstrate the weldability of high-Nb high-temperature processed (HTP) steels and provide extremely valuable information for future line pipe steel design and general steel manufacture, in the current study the toughness in simulated coarse-grained heat-affected zone (CGHAZ) of an X80 grade steel manufactured using HTP was evaluated. The simulated CGHAZs subjected to thermal cycles with various heat inputs (HIs) (0.8 to 5.0 kJ/mm) were produced using a Gleeble 3500 simulator. The microstructures and corresponding mechanical properties were investigated by means of optical microscopy, scanning electron microscopy, electron backscatter diffraction, hardness testing, and Charpy V-notch (CVN) testing. The microstructural examination shows that the simulated CGHAZs consisted of a bainite-dominant microstructure and relatively low amount (\u3c2 \u3epct) of martensite-austenite (M-A) constituent. The prior austenite grain size was controlled to be 45 to 55 µm at HIs of 0.8 to 3.5 kJ/mm, and remarkably increased to 85 µm at an HI of 5 kJ/mm. The results of CVN testing suggest that superior toughness can be achieved in the studied range of HIs (0.8 to 5 kJ/mm). This is thought to be associated with the combined effects of bainitic microstructure and low M-A fraction as well as comparatively fine austenite grain size in the studied CGHAZs

    Neuronal correlates of encoding and retrieval in episodic memory during a paired-word association learning task : a functional magnetic resonance imaging study

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    The investigation of memory function using functional magnetic resonance imaging (fMRI) is an expanding field of research. The aim of this study was to demonstrate brain-activity patterns related to a word-pair association task employing a whole-brain EPI sequence. Six right-handed, healthy male volunteers (mean age: 27.5 years) took part in the study. fMRI was performed at a field strength of 1.5 Tesla with 26–32 slices parallel to the AC-PC line, depending on individual brain size. Distributed brain regions were activated in episodic encoding and retrieval with similarities, but also (distinct) differences in activation patterns. Bilateral prefrontal cortical areas were involved when comparing encoding as well as retrieval to the reference condition (nonsense words). Furthermore, activation was observed in cerebellar areas during encoding, and activation in bilateral parietal areas (precuneus and inferior parietal cortex) was differentially more pronounced during retrieval. The activation of left dorsomedial thalamus during retrieval of high imagery-content word-pair associates may point to the role of this structure in episodic retrieval. The direct cognitive subtraction of encoding minus retrieval yielded a differentially larger left prefrontal activation. There was a differentially higher right prefrontal activation during retrieval than during encoding, underlining the proposed right/left asymmetry for episodic memory processes

    Adding Constraints to Logic-based Formalisms

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    Constraints are predefined relations with a special implementation mechanism. Logic formalisms provide specific reasoning facilities. We look at the effect of adding constraints to existing logic-based executable formalisms, focussing on the semantics of the combined formalisms. We find that in cases where this has been successful the operations of the formalism can be formulated logically and then extended easily to constraints. In many cases a disjunctive property of the constraints is reflected in the combined formalism, to the detriment of efficiency. 1 Introduction Constraints are essentially relations among variables ranging over fixed domains. Since most logics incorporate predicate symbols -- which are interpreted as relations -- and variables, there is clearly a degree of compatibility between constraint- and logic-based formalisms. Indeed, in some sense both constraint programming and logic programming can be considered part of an umbrella relational programming paradigm. ..

    Intensionality, Definability and Computation

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    We look at intensionality from the perspective of computation. In particular, we review how game semantics has been used to characterize the sequential functional processes, leading to powerful and flexible methods for constructing fully abstract models of programming languages, with applications in program analysis and verification. In a broader context, we can regard game semantics as a first step towards developing a positive theory of intensional structures with a robust mathematical structure, and finding the right notions of invariance for these structures

    PrIC3: Property Directed Reachability for MDPs

    No full text
    IC3 has been a leap forward in symbolic model checking. This paper proposes PrIC3 (pronounced pricy-three), a conservative extension of IC3 to symbolic model checking of MDPs. Our main focus is to develop the theory underlying PrIC3. Alongside, we present a first implementation of PrIC3 including the key ingredients from IC3 such as generalization, repushing, and propagation.ISSN:0302-9743ISSN:1611-334
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