  We propose in this paper a new approach to assess the relationship between
XACML policies. Our approach spans over three steps. In the first one, the
XACML policies are mapped to terms of a boolean ring while taking into account
XACML policy and rule combining algorithms. In the second step, the
relationship problem between XACML policies is transformed into a validity
problem in a boolean ring. In the third step, the validity problem is resolved
using a dedicated rewriting system. The convergence of the rewriting system is
proved in this paper. Moreover, the approach is implemented and its performance
is evaluated. The results show that our approach enjoys better performance and
memory cost than the best so far published SMT based approach.
