Chinese wall security policy-an aggressive model

In Brewer and Nash's Chinese Wall security policy model, there is a very strong implicit assumption that the 'conflict of interest' is an equivalence relation. It is called the BN-axiom. Such axiom is valid only for some very special circumstances. By modifying their formulation, a modified Brewer and Nash model without BN-axiom is defined. Such model turns out to be rather 'conservative' in the sense that the Chinese Walls are built within Chinese territory; it is not really a Chinese Wall model. Next, a new formal model is introduced in which Chinese Walls are built right on the boundary of China-an aggressive model for Chinese Wall security policy.<>