Flaws and Remedies of the MIDD Approach

We found that the Multi-data-type Interval Decision Diagrams (MIDD) approach proposed by Ngo et al. has some flaws: the way in which the critical mark of an attribute is represented does not retain the critical information, definition of the internal node is not entirely correct, and there are bugs in the corresponding algorithms. The first flaw could lead to potential missing attribute attacks, the second one wastes resources, and the last one makes the decision diagrams inconsistent. Two solutions were proposed to fix the first flaw. The first solution is to expand the scope of representation of internal nodes from only normal attributes of subject, object, operations, and environmental conditions to other required elements so that the critical attribute marks, obligations and/or advices, etc. are also represented by nodes. The second solution is to bind the critical mark of an attribute to its value. For the second flaw, corresponding definition was revised. For the third problem, a debug suggestion was made. The corresponding decision diagrams showed that the proposed schemes can overcome these problems of the MIDD approach.