Equational rules for rewriting logic

AbstractIn addition to equations and rules, we introduce equational rules that are oriented while having an equational interpretation. Correspondence between operational behavior and intended semantics is guaranteed by a property of coherence, which can be checked by examination of critical pairs and linearity conditions. We present applications of this theory to three examples where the rewrite relation is interpreted, respectively, as equality, transition and deduction

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Temperature-dependent Raman scattering of KTa1-xNbxO3 thin films

We report a Raman scattering investigation of KTa1-xNbxO3 (x = 0.35, 0.5) thin films deposited on MgO and LaAlO3 as a function of temperature. The observed phase sequence in the range from 90 K to 720 K is similar to the structural phase transitions of the end-member material KNbO3. Although similar in the phase sequence, the actual temperatures observed for phase transition temperatures are significantly different from those observed in the literature for bulk samples. Namely, the tetragonal (ferroelectric) to cubic (paraelectric) phase transition is up to 50 K higher in the films when compared to bulk samples. This enhanced ferroelectricity is attributed to biaxial strain in the investigated thin films

Observation of magnetization reversal in epitaxial Gd0.67Ca0.33MnO3 thin films

High quality epitaxial thin films of Gd0.67Ca0.33MnO3 have been deposited onto (100) SrTiO3 substrates by pulsed-laser deposition. Enhanced properties in comparison with bulk samples were observed. The magnetic transition temperature (Tc) of the as-grown films is much higher than the corresponding bulk values. Most interestingly, magnetization measurements performed under small applied fields, exhibit magnetization reversals below Tc, no matter whether the film is field-cooled (FC) or zero-field-cooled (ZFC). A rapid magnetization reversal occurs at 7 K when field cooled, while as for the ZFC process the magnetization decreases gradually with increasing temperatures, taking negative values above 7 K and changing to positive values again, above 83 K. In higher magnetic fields the magnetization does not change sign. The reversal mechanism is discussed in terms of a negative exchange f-d interaction and magnetic anisotropy, this later enhanced by strain effects induced by the lattice mismatch between the film and the substrate.Comment: 16 pages, 4 figure

Vivre loin de ses parents quand on est un jeune adulte:quel effet sur le lien de confidence?

Dans cet article, nous analysons dans quelle mesure les jeunes adultes mentionnent moins leurs parents comme des partenaires importants de discussion lorsqu’ils vivent éloignés d’eux. À partir d’un échantillon représentatif des jeunes de 18 à 34 ans vivant en Suisse, nous montrons que, d’une manière générale, les jeunes vivant à distance de leurs parents ne sont pas moins nombreux à partager un lien de confidence avec eux. Toutefois, le lien avec les parents est particulièrement sensible à la distance dans le cas des jeunes femmes ayant elles-mêmes des enfants. Pour une jeune femme, avoir un enfant augmente les chances de citer sa mère ou son père comme confidents en situation de proximité géographique et les diminue en cas d’éloignement. De plus, les jeunes mères éloignées de leur milieu d’origine ne trouvent pas ailleurs le soutien affectif qu’elles trouvent habituellement dans la proximité spatiale avec leurs parents. Associée à certains évènements familiaux, la distance géographique contribue dès lors à reconfigurer les dynamiques relationnelles et à renforcer les inégalités de genre au sein des familles. Plus généralement, ces résultats soulignent l’importance d’accorder davantage d’attention à la mobilité et à la distance géographique dans les recherches sur la famille et les relations intergénérationnelles.In this article, we analyze to what extent young people mention less their parents as important discussion partners when they live away from them. Using a representative sample of young people aged 18-34 living in Switzerland, we show that, overall, young people living away from their parents are not less likely to confide in them. However, parent-child relationships vary strongly with distance in the case of young mothers. For a young woman, having a child increases the likelihood of citing her mother or father as a confidant if parents live close by, and decreases this likelihood if parents live away. Moreover, young mothers geographically distanced from their parents do not find elsewhere the emotional support that they usually receive when they live in close proximity to their parents. Associated with specific family events, geographic distance therefore contributes to reconfiguring relational dynamics and worsening gender inequalities within families. This study points out that spatial mobility and geographic distance should receive more attention in research on families and intergenerational relations

Reach Set Approximation through Decomposition with Low-dimensional Sets and High-dimensional Matrices

Approximating the set of reachable states of a dynamical system is an algorithmic yet mathematically rigorous way to reason about its safety. Although progress has been made in the development of efficient algorithms for affine dynamical systems, available algorithms still lack scalability to ensure their wide adoption in the industrial setting. While modern linear algebra packages are efficient for matrices with tens of thousands of dimensions, set-based image computations are limited to a few hundred. We propose to decompose reach set computations such that set operations are performed in low dimensions, while matrix operations like exponentiation are carried out in the full dimension. Our method is applicable both in dense- and discrete-time settings. For a set of standard benchmarks, it shows a speed-up of up to two orders of magnitude compared to the respective state-of-the art tools, with only modest losses in accuracy. For the dense-time case, we show an experiment with more than 10.000 variables, roughly two orders of magnitude higher than possible with previous approaches

Analysing personal networks in geographical space beyond the question of distance

International audienceRecent literature recognises the importance of situating social networks in spatial context. Yet, the spatial analysis of personal networks has often been limited to examining residential distances between actors. While distance is a central characteristic of social relationships, it is a poor indicator for understanding the intricacies of the geographical space, places and personal networks. This study develops an original approach for mapping and analysing personal networks based on their geographical scope and the distribution of the residential locations of network members in relevant geographical areas. We perform a factor and cluster analysis to identify the major geographical patterns of personal networks using two samples of egocentric networks from France and Switzerland. We validate the approach first by interpreting the patterns both quantitatively and qualitatively, and second by examining how these patterns relate to important social characteristics of respondents and their personal networks. We conclude by discussing the significance of this approach for integrating geographical information into the analysis of personal networks and for rethinking networks and the geographical space as co‐constituted