The Role of Quasi-identifiers in k-Anonymity Revisited

The concept of k-anonymity, used in the recent literature to formally evaluate the privacy preservation of published tables, was introduced based on the notion of quasi-identifiers (or QI for short). The process of obtaining k-anonymity for a given private table is first to recognize the QIs in the table, and then to anonymize the QI values, the latter being called k-anonymization. While k-anonymization is usually rigorously validated by the authors, the definition of QI remains mostly informal, and different authors seem to have different interpretations of the concept of QI. The purpose of this paper is to provide a formal underpinning of QI and examine the correctness and incorrectness of various interpretations of QI in our formal framework. We observe that in cases where the concept has been used correctly, its application has been conservative; this note provides a formal understanding of the conservative nature in such cases.Comment: 17 pages. Submitted for publicatio

Desarrollo de modelos estadísticos para la predicción de propiedades mecánicas del hormigón simple

Compressive strength of concrete is considered as an index property of the concrete and therefore other mechanical properties of concrete such as flexural strength and modulus of elasticity are correlated with it. The standard code practices of different nations provide empirical corelations between compressive strength and mechanical properties. However, it is observed that these correlations yield deviating results. Present paper aims on developing statistical models for accurately estimating these properties based on experimental results. Plain concrete cube, cylinder, and beam specimens are cast with varying water-cement ratio and aggregate-cement ratio. Based on experimental results, the prediction models for compressive strength, flexural strength, and modulus of elastic are developed. Experimental results are compared with the results obtained from generated statistical models as well as with the results available from literature. It is found that the present models accurately predict the mechanical properties of concretes.La resistencia a la compresión del hormigón se considera una propiedad índice del hormigón y, por lo tanto, otras propiedades mecánicas del hormigón, como la resistencia a la flexión y el módulo de elasticidad, están correlacionadas con ella. Las prácticas del código estándar de diferentes países proporcionan correlaciones empíricas entre la resistencia a la compresión y las propiedades mecánicas. Sin embargo, se observa que estas correlaciones arrojan resultados desviados. El presente artículo tiene como objetivo desarrollar modelos estadísticos para estimar con precisión estas propiedades en base a resultados experimentales. Las muestras de cubos, cilindros y vigas de concreto simple se moldean con una relación agua-cemento y una relación agregado-cemento variables. Con base en los resultados experimentales, se desarrollan los modelos de predicción de la resistencia a la compresión, la resistencia a la flexión y el módulo de elasticidad. Los resultados experimentales se comparan con los resultados obtenidos a partir de modelos estadísticos generados, así como con los resultados disponibles de la literatura. Se encuentra que los modelos actuales predicen con precisión las propiedades mecánicas de los hormigones

Apparative Probleme bei der Untersuchung der Konstanz des Wahrnehmungsraumes - und ein neues Verfahren zu ihrer Lösung

An important usage of time sequences is for discovering temporal patterns of events (a special type of data mining). This process usually starts with the specification by the user of an event structure which consists of a number of variables representing events and temporal constraints among these variables. The goal of the data mining is to find temporal patterns, i.e., instantiations of the variables in the structure, which frequently appear in the time sequence. This paper introduces event structures that have temporal constraints with multiple granularities (TCGs). Testing the consistency of such structures is shown to be NP-hard. An approximate algorithm is then presented. The paper also introduces the concept of a timed automation with granularities (TAGs) that can be used to find in a time sequence occurrences of a particular TCG with instantiated variables. The TCGs, the approximate algorithm and the TAGs are shown to be useful for obtaining effective data mining procedures

Flexible Resolution of Authorisation Conflicts in Distributed Systems

Flexible Resolution of Authorisation Conflicts in Distributed System