Computers

  2010 MAR 11 - (VerticalNews.com) -- According to recent research published in the journal Distributed and Parallel Databases, "In this paper we present results on the problem of maintaining materialized top-k views and provide results in two directions. The first problem we tackle concerns the maintenance of top-k views in the presence of high deletion rates."

  "We provide a principled method that complements the inefficiency of the state of the art independently of the statistical properties of the data and the characteristics of the update streams. The second problem we have been concerned with has to do with the efficient maintenance of multiple top-k views in the presence of updates to their base relation. To this end, we provide theoretical guarantees for the nucleation (practically, inclusion) of a view with respect to another view and the reflection of this property to the management of updates," wrote E. Baikousi and colleagues, University of Ioannina ...read more

  2010 MAR 11 - (VerticalNews.com) -- According to recent research published in the journal Distributed and Parallel Databases, "Current provenance stores associated with workflow management systems (WfMSs) capture enough coarse-grained information to describe which datasets were used and which processes were run. While this information is enough to rebuild a workflow run, it is not enough to facilitate user understanding."

  "Because the data is manipulated via a series of black boxes, it is often impossible for a human to understand what happened to the data. In this work, we highlight the missing information that can assist user understanding. Unfortunately, provenance information is already very complex and difficult for a user to comprehend, which can be exacerbated by adding the extra information needed for deeper blackbox understanding. In order to alleviate this, we develop a model of provenance answers that follow a ''roll up'', ''drill down'' strategy. We evaluate these techniques to determine if users have better understanding of provenance information. We show how this information can be captured by workflow management systems, and that the structures and information needed for this model are a negligible addition to standard provenance stores," wrote A. Chapman and colleagues ...read more

  2010 MAR 11 - (VerticalNews.com) -- According to recent research published in the Journal of Parallel and Distributed Computing, "This paper shows that shared-coin algorithms can be combined to optimize several complexity measures, even in the presence of a strong adversary."

  "By combining shared coins of Bracha and Rachman (1991) [10] and of Aspnes and Waarts (1996) [7], this yields a shared-coin algorithm, and hence, a randomized consensus algorithm, with O(n log(2) n) individual work and O(n(2) log n) total work, using single-writer registers. This improves upon each of the above shared coins (where the former has a high cost for individual work, while the latter reduces it but pays in the total work), and is currently the best for this model," wrote J. Aspnes and colleagues ...read more