In this paper, we present an enhanced use of RBAC features in articulating a security policy for access control in medical database systems. The main advantage of this implementation is that it supports both MAC and DAC features at the same time; a feature that has been proved to be necessary in healthcare environments. The eMEDAC security policy that results from the above implementation provi...

This paper introduces the notion of safety and availability checking for user authorization query processing, and develop a recursive algorithm use the ideas from backtracking-based search techniques to search for the optimal solution. For the availability checking, we introduce the notion of max activatable set (MAS), and show formally how MAS can be determined in a hybrid role hierarchy. For ...

Access control is a difficult security issue for enterprise organizations. Role-based access control (RBAC) model is well known and recognized as a good security model for enterprise environment. Though RBAC is a good model, administration of RBAC including building and maintaining access control information remains a difficult problem in large companies. RBAC model itself does not tell the sol...

We demonstrate how one can use the formal concept analysis (FCA) to obtain the role hierarchy for the role based access control from the existing access control matrix. We also discuss assesed by means of FCA the quality of security system and finding users with excess permissions.

In every communicative context, each participant assumes some kind of role and negotiates some type of relationship with their counterparts. In the e-learning domain, the roles (e.g. instructor, learner, marker, administrator, etc.) for participants are well structured and relationships (e.g. one-to-one, one-to-many, hierarchical, etc.) among roles are relatively predictable. This paper propose...

Generalized Temporal Role Based Access Control (GTRBAC) model that captures an exhaustive set of temporal constraint needs for access control has recently been proposed. GTRBAC’s language constructs allow one to specify various temporal constraints on role, user-role assignments and role-permission assignments. In this paper, we present the notion of different types of role hierarchies based on...

We propose an effective administration model using organizational structure for a decentralized role-based access control environment. Access control administration is a critical issue for large organizations and information systems. A large organization needs decentralized access control by multiple security officers because it has many users and information objects, and a single security offi...

This paper presents a novel approach to the task of semantic role labelling for event nominalisations, which make up a considerable fraction of predicates in running text, but are underrepresented in terms of training data and difficult to model. We propose to address this situation by data expansion. We construct a model for nominal role labelling solely from verbal training data. The best qua...

This paper presents an empirical study on the robustness and generalization of two alternative role sets for semantic role labeling: PropBank numbered roles and VerbNet thematic roles. By testing a state–of–the–art SRL system with the two alternative role annotations, we show that the PropBank role set is more robust to the lack of verb–specific semantic information and generalizes better to in...