We focus on mixtures of factor analyzers from the perspective of a method for model-based density estimation from high-dimensional data, and hence for the clustering of such data. This approach enables a normal mixture model to be fitted to a sample of n data points of dimension p, where p is...

Current proposals for access control languages cannot specify policies required by specific application scenarios (e.g. a database system to enforce privacy regulations), may also contain design flaws, and are incompatible. In this dissertation, we extend RBAC with new components to meet...