214 research outputs found

    Construct redundancy in process modelling grammars: Improving the explanatory power of ontological analysis

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    Conceptual modelling supports developers and users of information systems in areas of documentation, analysis or system redesign. The ongoing interest in the modelling of business processes has led to a variety of different grammars, raising the question of the quality of these grammars for modelling. An established way of evaluating the quality of a modelling grammar is by means of an ontological analysis, which can determine the extent to which grammars contain construct deficit, overload, excess or redundancy. While several studies have shown the relevance of most of these criteria, predictions about construct redundancy have yielded inconsistent results in the past, with some studies suggesting that redundancy may even be beneficial for modelling in practice. In this paper we seek to contribute to clarifying the concept of construct redundancy by introducing a revision to the ontological analysis method. Based on the concept of inheritance we propose an approach that distinguishes between specialized and distinct construct redundancy. We demonstrate the potential explanatory power of the revised method by reviewing and clarifying previous results found in the literature

    Dipion Resonant Systems Produced in 4.5 GeV/c π⁺d Interactions : Saclay-Orsay-Bologna Collaboration

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    This paper presents an analysis of the features observed in the neutral mass spectrum of events of this type: π+d - pp neutral

    Comparison of Isobar Production in pp and p̅n Interactions at 2.8 GeV/c

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    The reactions pp→N*++(1238)n and p̅ n→N̅ *--(1238)p at 2.8 GeV/c incident laboratory momentum are analyzed with the Brookhaven National Laboratory 20-in. bubble chamber. Isobar and anti-isobar production differential cross sections and decay angular distributions are compared with the predictions of an absorptive single-pion-exchange model. The absolute values, shapes, and ratios of the cross sections are in good agreement with the theory when the absorptive parameters γ1 and γ2 are 0.033 and 0.016 for the p̅ n reaction, and 0.057 and 0.019, respectively, for the pp reaction

    π‾p→π⁰π⁰n Near Threshold and Chiral Symmetry Breaking

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    Total cross sections, angular, and mass distributions for the reaction π-p→π0π0n have been measured for pπ-(lab)=7–140 MeV/c above threshold. The threshold amplitude was used to determine a value for the chiral-symmetry-breaking parameter, ξ, of -0.98±0.52. The ππ scattering lengths aI for isospin I=0 and 2 are derived from this result, together with a current-algebra sum rule. The results are a0=(0.207±0.028)mπ-1 and a2=(-0.022±0.011)mπ-1. These values are consistent with chiral symmetry broken by the Weinberg ππ interaction and the effects of the f0(975) scalar meson

    Radiative Kaon Capture on Deuterium and the Λn Scattering Lengths

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    The photon spectrum from K-d→Λnγ at rest has been measured for the first time. We obtained the branching ratio, in the end-point region, of (1.89±0.12±0.28)×10-3 where the first error is statistical and the second is systematic. We have found that the shape of the photon energy spectrum is consistent with the distribution calculated by Workman and Fearing with Λn scattering lengths and effective ranges predicted by the Nijmegen group
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