Attribute-based access control (ABAC) is a promising alternative to traditional models of access control (i.e. discretionary access control (DAC), mandatory access control (MAC) and role-based access control (RBAC)) that is drawing attention in both recent academic literature and industry application. However, formalization of a foundational model of ABAC and large scale adoption are still lack...

Tree-based multidimensional indexes are integral to efficient querying in multimedia and GIS applications. These indexes frequently use shapes in internal tree nodes to describe the data stored in a subtree below. We show that the standard Minimum Bounding Rectangle descriptor can lead to significant inefficiency during tree traversal, due to false positives. We also observe that there is often...

Laserscanning produces large sets of multidimensional point data, which demand for an effective and efficient organization and storage. Adequate data structures must perform specific spatial queries and operations in order to support the computation and / or the construction of surface models. Because of their increasing size, it is not advisable to organize the clouds of points by mainmemory d...

The basic form of renal replacement therapy is haemodialysis. The duration and efficacy of this treatment depends on well-functioning vascular access. Short-term or long-term catheters are used if the arterial-venous fistula placement is not possible or not indicated. According to the recommendations of the NKF DOQI (National Kidney Foundation Disease Outcomes Quality Initiative), the first cho...

We present a new approach for indexing animated objects and efficiently answering queries about their position in time and space. In particular, we consider an animated movie as a evolution. A movie is viewed as an ordered sequence of frames, where each frame is a 2-dimensional space occupied by the objects that appear in that frame. The queries of interest are range queries of the form: “find ...

The database research community has been building methods to store, access, and update data for more than four decades. Throughout the evolution of the structures and techniques used to access data, access methods adapt to the ever changing hardware and workload requirements. Today, even small changes in the workload or the hardware lead to a redesign of access methods. The need for new designs...

Role Based Access Control (RBAC) is a methodology for providing users in an IT system specific permissions like write or read to users. It abstracts from specific users and binds permissions to user roles. Similarly, one can abstract from specific documents and bind permission to document types. In this paper, we apply Description Logics (DLs) to formalize RBAC. We provide a thorough discussion...

We will present some ideas about sharing a secret in a monotonic access structure. We show the relations which occur between the method of encrypting a monotonic access structure with the use of basis sets or maximal unprivileged sets, and that based on a logical formula (used by Benaloh and Leichter in [1]). We will also give some facts connected with the problem of security, including the asp...