Hi
Shriram Krisnarmurthi (DR Scheme) presented a nice model to identify
problem in complex modern access-control
at dagsthul.
What is interesting is that they offer a tool (margrave) to see if
there is no strange configuration, especially in the sense
of evolution of the access control.
Apparently now there are languages to express access control: XACML
seems the most important.
Stef