This paper presents a study of the movements of a humanoid head-and-neck robot called Eddie. Eddie has a musculo-skeletal structure similar to that found in human necks enabling it to perform head movements that are comparable with human head movements. This study compares the movements of Eddie with those of a more conventional robotic neck structure and with those of a human head. Results show that Eddie's movements are perceived as significantly more natural and by trend more lifelike than the conventional head's. No differences were found with respect to the impression of human-likeness, consciousness, and elegance.

In this article we show how to model a range of notions in the context of delegation and revocation applied to security scenarios. We demonstrate how a range of delegation–revocation models and policies may be represented in pictorial form and formally represented in terms of reactive Kripke models and a first-order policy specification language. We translate first-order representations of our reactive Kripke models into an equivalent Answer Set Programming form that enables users to apply flexibly well-defined definitions of predicates to represent their requirements in terms of delegation–revocation policy specification.

We describe an approach that aims to unify certain aspects of access control and privacy. Our unified approach is based on the idea of axiomatizing access control in general terms. We show how multiple access control and privacy models and policies can be uniformly represented as particular logical theories in our axiom system. We show that our approach translates into different practical languages for implementation and we give some performance measures for some candidate implementations of our approach.

We address the problem of providing data subjects with self-selected controls on access to their personal information. Existing approaches for this are not always sufficient in terms of offering the degrees of control and scope for individualization of access policies that are needed for personal data protection (and usage). We introduce a conceptual framework, a syntax, a semantics, and an axiomatization of a generalized form of access control meta-model, which may be specialized in various ways to enable data subjects to specify flexibly what access controls are to apply on their personal data.

We address some fundamental questions, which were raised by Atluri and Ferraiolo at SACMAT'08, on the prospects for and benefits of a meta-model of access control. We demonstrate that a meta-model for access control can be defined and that multiple access control models can be derived as special cases. An anticipated consequence of the contribution that we describe is to encourage researchers to adopt a meta-model view of access control rather than them developing the next 700 particular instances of access control models.

Standard SQL is insufficiently expressive for representing many access control policies that are needed in practice. Nevertheless, we show how rich forms of access control policies can be defined within SQL when small amounts of contextual information are available to query evaluators. Rather than the standard, relational structure perspective that has been adopted for fine-grained access control, we consider instead the representation of dynamic fine-grained access control (DFMAC) policy requirements at the access policy level. We also show how DFMAC policies may be represented in SQL and we give some performance results for an implementation of our approach. These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

We address the problem of defining access control policies that may be used in the evaluation of requests made by client actors, in the course of e-trading, to perform actions on the resources maintained by an e-collective. An e-collective is a group of agents that may act individually or in conjunction with other agents to satisfy a client's request to act. Our principal contribution to this key problem is to define formally an access control model in terms of which policies may be specified for helping to ensure that only legitimate forms of client actions are performed in the course of engaging in e-trading. We call this model the action control model. In action control, the notion of intentional, empowered, authorized actions, that may be performed individualistically or jointly with other agents, and in a manner that is consistent with a group ethos, is the basis for specifying a set of permissives. A permissive is a generalization of the notion of a permission (as the latter term is usually interpreted in access control). In addition to the formal definition of the action control model, we give examples of action control policy specifications and we describe a candidate implementation and performance measures.

Despite their widespread adoption, Role-based Access Control (RBAC) models exhibit certain shortcomings that make them less than ideal for deployment in, for example, distributed access control. In the distributed case, standard RBAC assumptions (e.g., of relatively static access policies, managed by human users, with complete information available about users and job functions) do not necessarily apply. Moreover, RBAC is restricted in the sense that it is based on one type of ascribed status, an assignment of a user to a role. In this article, we introduce the status-based access control (SBAC) model for distributed access control. The SBAC model (or family of models) is based on the notion of users having an action status as well as an ascribed status. A user's action status is established, in part, from a history of events that relate to the user; this history enables changing access policy requirements to be naturally accommodated. The approach can be implemented as an autonomous agent that reasons about the events, actions, and a history (of events and actions), which relates to a requester for access to resources, in order to decide whether the requester is permitted the access sought. We define a number of algebras for composing SBAC policies, algebras that exploit the language that we introduce for SBAC policy representation: identification-based logic programs. The SBAC model is richer than RBAC models and the policies that can be represented in our approach are more expressive than the policies admitted by a number of monotonic languages that have been hitherto described for representing distributed access control requirements. Our algebras generalize existing algebras that have been defined for access policy composition. We also describe an approach for the efficient implementation of SBAC policies.

We introduce a generalization of Role-based Access Control that we call the Action-Status Access Control (ASAC) model. The ASAC model addresses certain shortcomings with RBAC models when applied in distributed computing contexts. The ASAC model is based on the notion of status, and a nonmonotonic theory of access control that is founded upon the notions of events, actions and times. The approach allows automatic changes to be made to policy requirements and agent authorizations that may be based, in part, on an agent's intentional behaviors.

We introduce a new usage control model for protecting Web resources. We also describe specification and implementation languages for policies that are defined in terms of our usage control model.

We describe the use of a flexible meta-interpreter for performing access control checks on deductive databases. The meta-program is implemented in Prolog and takes as input a database and an access policy specification. We then proceed to specialise the meta-program for a given access policy and intensional database by using the logen partial evaluation system. In addition to describing the programs involved in our approach, we give a number of performance measures for our implementation of an access control checker, and we discuss the implications of using this approach for access control on deductive databases. In particular, we show that by using our approach we get flexible access control with virtually zero overhead.

We show how a range of role-based access control (RBAC) models may be usefully represented as constraint logic programs, executable logical specifications. The RBAC models that we define extend the "standard" RBAC models that are described by Sandhu et al., and enable security administrators to define a range of access policies that may include features, like denials of access and temporal authorizations, that are often useful in practice, but which are not widely supported in existing access control models. Representing access policies as constraint logic programs makes it possible to support certain policy options, constraint checks, and administrator queries that cannot be represented by using related methods (like logic programs). Representing an access control policy as a constraint logic program also enables access requests and constraint checks to be efficiently evaluated.