Learning and Reasoning about Norms using Neural-Symbolic Systems

in International Conference on Autonomous Agents and Multiagent Systems, AAMAS 2012, Valencia, Spain, June 4-8, 2012 (2012)

In this paper we provide a neural-symbolic framework to model, reason about and learn norms in multi-agent systems. To this purpose, we define a fragment of Input/Output (I/O) logic that can be embedded ... [more ▼]

In this paper we provide a neural-symbolic framework to model, reason about and learn norms in multi-agent systems. To this purpose, we define a fragment of Input/Output (I/O) logic that can be embedded into a neural network. We extend d’Avila Garcez et al. Connectionist Inductive Learning and Logic Programming System (CILP) to translate an I/O logic theory into a Neural Network (NN) that can be trained further with examples: we call this new system Normative- CILP (N-CILP). We then present a new algorithm to handle priorities between rules in order to cope with normative issues like Contrary to Duty (CTD), Priorities, Exceptions and Permissions. We illustrate the applicability of the framework on a case study based on RoboCup rules: within this working example, we compare the learning capacity of a network built with N-CILP with a non symbolic neural net- work, we explore how the initial knowledge impacts on the overall performance, and we test the NN capacity of learn- ing norms, generalizing new Contrary to Duty rules from examples. [less ▲]

A Conditional Constructive Logic for Access Control and Its Sequent Calculus

in Automated Reasoning with Analytic Tableaux and Related Methods (2011)

In this paper we study the applicability of constructive conditional logics as a general framework to define decision procedures in access control logics. To this purpose, we formalize the assertion A ... [more ▼]

In this paper we study the applicability of constructive conditional logics as a general framework to define decision procedures in access control logics. To this purpose, we formalize the assertion A says φ, whose intended meaning is that principal A says that φ, as a conditional implication. We introduce CondACL , which is a conservative extension of the logic ICL recently introduced by Garg and Abadi. We identify the conditional axioms needed to capture the basic properties of the “says” operator and to provide a proper definition of boolean principals. We provide a Kripke model semantics for the logic and we prove that the axiomatization is sound and complete with respect to the semantics. Moreover, we define a sound, complete, cut-free and terminating sequent calculus for CondACL , which allows us to prove that the logic is decidable. We argue for the generality of our approach by presenting canonical properties of some further well known access control axioms. The identification of canonical properties provides the possibility to craft access control logics that adopt any combination of axioms for which canonical properties exist. [less ▲]

Secommunity: A Framework for Distributed Access Control

in Logic Programming and Nonmonotonic Reasoning (2011)

We describe an approach for distributed access control policies that is based on a nonmonotonic semantics and the use of logic programming for policy specification and the evaluation of access requests ... [more ▼]

We describe an approach for distributed access control policies that is based on a nonmonotonic semantics and the use of logic programming for policy specification and the evaluation of access requests. Our approach allows assertions of relevance to access control to be made by individual agents or on a community-based level and different strengths of testimonial warrant may be distinguished by using various logical operators. We describe a form of ASP that allows for remote access request evaluation and we discuss a DLV-based implementation of our approach. [less ▲]

Dynamics in Delegation and Revocation Schemes: A Logical Approach

in DBSec (2011)

In this paper we first introduce a logic for describing formally a family of delegation and revocation models that are based on the work in Hagström et al.. We then extend our logic to accommodate an ... [more ▼]

In this paper we first introduce a logic for describing formally a family of delegation and revocation models that are based on the work in Hagström et al.. We then extend our logic to accommodate an epistemic interpretation of trust within the framework that we define. What emerges from this work is a rich framework of formally well-defined delegation and revocation schemes that accommodates an important trust component. [less ▲]

Modal Access Control Logic - Axiomatization, Semantics and FOl Theorem Proving

in STAIRS 2010 (2010)

We present and study a Modal Access Control Logic (M-ACL) to specify and reason about access control policies. We identify canonical properties of well-known access control axioms. We provide a Hilbert ... [more ▼]

We present and study a Modal Access Control Logic (M-ACL) to specify and reason about access control policies. We identify canonical properties of well-known access control axioms. We provide a Hilbert-style proof-system and we prove soundness, completeness and decidability of the logic. We present a sound and complete embedding of Modal Access Control Logic into First-Order Logic. We show how to use SPASS theorem prover to reason about access control policies expressed as formulas of Modal Access Control Logic, and we compare our logic with existing ones. [less ▲]

Higher-Order Coalition Logic

in Bibliothèque(s) : revue de l'Association des bibliothécaires de France (2010)

We introduce and study higher-order coalition logic, a multi modal monadic second-order logic with operators [{x}ψ]φ expressing that the coalition of all agents satisfying ψ(x) can achieve a state in ... [more ▼]

We introduce and study higher-order coalition logic, a multi modal monadic second-order logic with operators [{x}ψ]φ expressing that the coalition of all agents satisfying ψ(x) can achieve a state in which φ holds. We use neighborhood semantics to model extensive games of perfect information with simultaneous actions and we provide a framework reasoning about agents in the same way as it is reasoning about their abilities. We illustrate higher-order coalition logic to represent and reason about coalition formation and cooperation, we show a more general and expressive way to quantify over coalitions than quantified coalition logic, we give an axiomatization and prove completeness. [less ▲]

A meta-model of access control in a fibred security language

in Studia Logica (2009), 92(3), 437-477

The issue of representing access control requirements continues to demand significant attention. The focus of researchers has traditionally been on developing particular access control models and policy ... [more ▼]

The issue of representing access control requirements continues to demand significant attention. The focus of researchers has traditionally been on developing particular access control models and policy specification languages for particular applications. However, this approach has resulted in an unnecessary surfeit of models and languages. In contrast, we describe a general access control model and a logic-based specification language from which both existing and novel access control models may be derived as particular cases and from which several approaches can be developed for domain-specific applications. We will argue that our general framework has a number of specific attractions and an implication of our work is to encourage a methodological shift from a study of the particulars of access control to its generalities. [less ▲]

A Middleware for modeling Organizations and Roles in Jade

in Proceedings of PROMAS (2009)

Organizations and roles are often seen as mental constructs, good to be used during the design phase in Multi Agent Systems, but they have also been considered as first class citizens in MAS, when ... [more ▼]

Organizations and roles are often seen as mental constructs, good to be used during the design phase in Multi Agent Systems, but they have also been considered as first class citizens in MAS, when objective coordination is needed. Roles facilitate the coordination of agents inside an organization, and they give new abilities in the context of organizations, called powers, to the agents which satisfy the necessary requirements to play them. No general purpose programming languages for multiagent systems offer primitives to program organizations and roles as instances existing at runtime, so, in this paper, we propose our extension of the Jade framework, with Java primitives to program organizations structured in roles, and to enable agents to play roles in organizations. We provide classes and protocols which enable an agent to enact a new role in an organization, to interact with the role by invoking the execution of powers, and to receive new goals to be fulfilled. Roles and organizations can be on a different platform with respect to the role players, and communication is protocol-based. Since they can have complex behaviours, they are implemented by extending the Jade agent class. Our aim is to give to programmers a middle tier, built on the Jade platform, useful to solve with minimal implementative effort many coordination problems, and to offer a first, implicit, management of norms and sanctions. [less ▲]

How to Program Organizations and Roles in the JADE Framework

in Multiagent System Technologies, 6th German Conference, MATES 2008, Kaiserslautern, Germany, September 23-26, 2008. Proceedings (2008)

The organization metaphor is often used in the design and implementation of multiagent systems. However, few agent programming languages provide facilities to define them. Several frameworks are proposed ... [more ▼]

The organization metaphor is often used in the design and implementation of multiagent systems. However, few agent programming languages provide facilities to define them. Several frameworks are proposed to coordinate MAS with organizations, but they are not programmable with general purpose languages. In this paper we extend the JADE framework with primitives to program in Java organizations structured in roles, and to enable agents to play roles in organizations. Roles facilitate the coordination of agents inside an organization and offer new abilities (powers) in the context of organizations to the agents which satisfy the requirements necessary to play the roles. To program organizations and roles, we provide primitives which enable an agent to enact a new role in an organization to invoke powers. [less ▲]

Roles in Coordination and in Agent Deliberation: A Merger of Concepts

in Proceedings of AWESOME07 (2007)

In this paper we generalize and merge two models of roles used in multiagent systems which address complementary aspects: enacting roles and communication among roles in an organization or institution. We ... [more ▼]

In this paper we generalize and merge two models of roles used in multiagent systems which address complementary aspects: enacting roles and communication among roles in an organization or institution. We do this by proposing a metamodel of roles and specializing the metamodel to fit two existing models. We show how the two approaches can be integrated since they deal with complementary aspects: [1] focuses on roles as a way to specify interactions among agents, and, thus, it emphasizes the public character of roles. [2] focuses instead on how roles are played, and thus it emphasizes the private aspects of roles: how the beliefs and goals of the roles become the beliefs and goals of the agents. The former approach focuses on the dynamics of roles in function of the communication process. The latter approach focuses on the internal dynamics of the agents when they start playing a role or shift the role they are currently playing. [less ▲]