On the Notion of Redundancy in Access Control Policies

The evolution of information systems sees an increasing need of flexible and sophisticated approaches for the automated detection of anomalies in security policies. One of these anomalies is redundancy, which may increase the total cost of management of the policies and may reduce the performance of access control mechanisms and of other anomaly detection techniques. We consider three approaches that can remove redundancy from access control policies, progressively reducing the number of authorizations in the policy itself. We show that several problems associated with redundancy are NP-hard. We propose exact solutions to two of these problems, namely the Minimum Policy Problem, which consists in computing the minimum policy that represents the behaviour of the system, and the Minimum Irreducible Policy Problem, consisting in computing the redundancy-free version of a policy with the smallest number of authorizations. Furthermore we propose heuristic solutions to those problems. We also present a comparison between the exact and heuristics solutions based on experiments that use policies derived from bibliographical databases

PLC-beta2 is highly expressed in breast cancer and is associated with a poor outcome: a study on tissue microarrays.

Despite the identification of many putative biomarkers in breast cancer, a specific pattern of proteins to be used as a prognosticator is not well defined. A growing body of evidence supports the role of phospholipase C (PLC) in the invasion and metastasis of different tumors, including breast cancer. To assess whether the expression of specific PLC isoforms correlates with malignancy-related features of human breast tumors and, hence, could have prognostic significance, an immunohistochemical analysis of PLC-beta2 was performed on tissue microarrays and the relationship between PLC-beta2 expression and biological and clinico-pathological factors was assessed. The analysis of 77 samples of breast tumors with different histotypes revealed that PLC-beta2 is highly expressed in a large majority of the analyzed cancer tissue, particularly ductal and lobular carcinomas, in comparison with normal breast. The expression of PLC-beta2 in primary tumors correlated with size, proliferation index and final grade, while no significant relationship was observed with nodal status or estrogen receptor levels, or with the expression of tumor suppressor p53. Remarkably, high PLC-beta2 levels in primary tumors predict an unfavourable prognosis, suggesting the contribution of this protein to the progression of human mammary carcinomas. Our data indicate that PLC-beta2 expression correlates highly with breast cancer malignancy and suggest that it can be included, as an independent marker, among the prognostic indicators in current use

A Domain Specific Language for Modeling Differential Constraints of Mobile Robots

Kinematics and dynamics constraints of mobile robots can be modeled by means of differential equations. Simulation and sampling based path-planning algorithms need a model of these constraints in order to deal with non-holonomic mobile robots. Usually these models are hard-coded in the implementation of those algorithms and this makes hard their reuse. In order to design these algorithms in a modular and extensible way we have to explicitly represent the models of the robots and decouple them from algorithms implementation. We propose DCML, a Domain Specific Language that can be used in order to describe differential models, and a tool that allows developers to automatically generate the code that implements the model. We also aim to show how this Model-Driven Engineering technique can be used with good results. As a demonstration of what can be done by means of our DSL, we present the differential model of an omnidirectional holonomic robot called BART, and we show how this model can be integrated in a framework for path planning

Evolutionary Testing of PHP Web Applications with WETT

One of the current core requirements of web applications is the continuity of the service, because loss in availability can lead to severe economic losses. This is the main reason behind the growing interest in web application testing that offers to researchers several challenges, due to the peculiar nature of these applications. Several classical testing techniques have been extended to deal with web testing. In this paper we propose to extend to web application testing a recent search-based approach that optimizes the generation of the whole test suite. This approach has several advantages over common approaches that optimize the generation of a single test case at a time. We show the technological challenges we have had to face, the architecture of the tool WETT we have developed, and some preliminary results of the experiments