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We describe several new bottom-up approaches to problems in role engineering for Role-Based Access Control (RBAC). The salient problems are all NP-complete, even to approximate, yet we find that in instances that arise in practice these problems can be solved in minutes. We first consider role minimization, the process of finding a smallest collection of(More)
The use of tabling in logic programming allows bottom-up evaluation to be incorporated in a top-down framework, combining advantages of both. At the engine level, tabling also introduces issues not present in pure top-down evaluation, due to the need for subgoais and answers to access tables during resolution. This article describes the design,(More)
This paper describes work in our project funded by DARPA Dynamic Coalitions program to design, develop, and demonstrate a system for automatically managing security policies in dynamic networks.. Specifically, we aim to reduce human involvement in network management by building a practical network reconfiguration system so that simple security policies(More)
The well-founded model provides a natural and robust semantics for logic programs with negative literals in rule bodies. We implemented the well-founded semantics in the SLG-WAM of XSB 19]. Performance results indicate that the overhead of delay and simpliica-tion to Prolog | or tabled | evaluations is minimal. To compute the well-founded semantics, the(More)
CONTEXT Dental trauma has become an important attribute of dental public health. The primary requisite before actively dealing with such problems is to describe the extent, distribution, and associated variables with the specific condition. AIMS The aim of the present study was to assess the prevalence and distribution of traumatic dental injuries (TDI)(More)
Organizations, especially business enterprises, collect and store event logs generated by hardware devices and software applications in their networks. For example, firewalls log information about suspicious network traffic; and hypertext transfer protocol (HTTP) proxy servers log websites (or domains) accessed by hosts in an enterprise. Enterprises collect(More)
Tabled resolution improves e ciency as well as termination properties of logic programs by sharing answer computations across \similar" subgoals. Similarity based on subsumption of subgoals rather than variance (i.e., identity modulo variable renaming) promotes more aggressive sharing, but requires mechanisms to index answers from dynamically growing sets.(More)